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162 results on '"Gilles Peltier"'

1. The Phytophthora parasitica effector AVH195 interacts with ATG8, attenuates host autophagy, and promotes biotrophic infection

Author: Serena Testi, Marie-Line Kuhn, Valérie Allasia, Pascaline Auroy, Fantao Kong, Gilles Peltier, Sophie Pagnotta, Julie Cazareth, Harald Keller, and Franck Panabières
Subjects: Oomycete, Effector, Biotrophy, Autophagy, Vacuoles, Biology (General), QH301-705.5
Abstract: Abstract Background Plant pathogens secrete effector proteins into host cells to suppress immune responses and manipulate fundamental cellular processes. One of these processes is autophagy, an essential recycling mechanism in eukaryotic cells that coordinates the turnover of cellular components and contributes to the decision on cell death or survival. Results We report the characterization of AVH195, an effector from the broad-spectrum oomycete plant pathogen, Phytophthora parasitica. We show that P. parasitica expresses AVH195 during the biotrophic phase of plant infection, i.e., the initial phase in which host cells are maintained alive. In tobacco, the effector prevents the initiation of cell death, which is caused by two pathogen-derived effectors and the proapoptotic BAX protein. AVH195 associates with the plant vacuolar membrane system and interacts with Autophagy-related protein 8 (ATG8) isoforms/paralogs. When expressed in cells from the green alga, Chlamydomonas reinhardtii, the effector delays vacuolar fusion and cargo turnover upon stimulation of autophagy, but does not affect algal viability. In Arabidopsis thaliana, AVH195 delays the turnover of ATG8 from endomembranes and promotes plant susceptibility to P. parasitica and the obligate biotrophic oomycete pathogen Hyaloperonospora arabidopsidis. Conclusions Taken together, our observations suggest that AVH195 targets ATG8 to attenuate autophagy and prevent associated host cell death, thereby favoring biotrophy during the early stages of the infection process.
Published: 2024
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2. Role of an ancient light-harvesting protein of PSI in light absorption and photoprotection

Author: Yandu Lu, Qinhua Gan, Masakazu Iwai, Alessandro Alboresi, Adrien Burlacot, Oliver Dautermann, Hiroko Takahashi, Thien Crisanto, Gilles Peltier, Tomas Morosinotto, Anastasios Melis, and Krishna K. Niyogi
Subjects: Science
Abstract: LHCR proteins are ancient chlorophyll a-binding antennas that evolved in diverse algae of the red lineage. Here Lu et al. characterize a red lineage LHCR mutant and show reduced oxidative damage in high light but attenuated growth under low light, thus demonstrating how LHCR proteins impact the balance between photoprotection and light harvesting.
Published: 2021
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3. Corrigendum: Membrane Inlet Mass Spectrometry: A Powerful Tool for Algal Research

Author: Adrien Burlacot, François Burlacot, Yonghua Li-Beisson, and Gilles Peltier
Subjects: gas exchange, photosynthesis, carbonic anhydrase, CO2 concentrating mechanism, O2 evolution, H2 production, Plant culture, SB1-1110
Published: 2020
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4. Membrane Inlet Mass Spectrometry: A Powerful Tool for Algal Research

Author: Adrien Burlacot, François Burlacot, Yonghua Li-Beisson, and Gilles Peltier
Subjects: gas exchange, photosynthesis, carbonic anhydrase, CO2 concentrating mechanism, O2 evolution, H2 production, Plant culture, SB1-1110
Abstract: Since the first great oxygenation event, photosynthetic microorganisms have continuously shaped the Earth’s atmosphere. Studying biological mechanisms involved in the interaction between microalgae and cyanobacteria with the Earth’s atmosphere requires the monitoring of gas exchange. Membrane inlet mass spectrometry (MIMS) has been developed in the early 1960s to study gas exchange mechanisms of photosynthetic cells. It has since played an important role in investigating various cellular processes that involve gaseous compounds (O2, CO2, NO, or H2) and in characterizing enzymatic activities in vitro or in vivo. With the development of affordable mass spectrometers, MIMS is gaining wide popularity and is now used by an increasing number of laboratories. However, it still requires an important theory and practical considerations to be used. Here, we provide a practical guide describing the current technical basis of a MIMS setup and the general principles of data processing. We further review how MIMS can be used to study various aspects of algal research and discuss how MIMS will be useful in addressing future scientific challenges.
Published: 2020
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5. Subcellular Energetics and Carbon Storage in Chlamydomonas

Author: Adrien Burlacot, Gilles Peltier, and Yonghua Li-Beisson
Subjects: organelle, chloroplast, mitochondria, peroxisome, starch, oil, reductant, phosphorylating power, photosynthesis, metabolic shuttles, Cytology, QH573-671
Abstract: Microalgae have emerged as a promising platform for production of carbon- and energy- rich molecules, notably starch and oil. Establishing an economically viable algal biotechnology sector requires a holistic understanding of algal photosynthesis, physiology, cell cycle and metabolism. Starch/oil productivity is a combined effect of their cellular content and cell division activities. Cell growth, starch and fatty acid synthesis all require carbon building blocks and a source of energy in the form of ATP and NADPH, but with a different requirement in ATP/NADPH ratio. Thus, several cellular mechanisms have been developed by microalgae to balance ATP and NADPH supply which are essentially produced by photosynthesis. Major energy management mechanisms include ATP production by the chloroplast-based cyclic electron flow and NADPH removal by water-water cycles. Furthermore, energetic coupling between chloroplast and other cellular compartments, mitochondria and peroxisome, is increasingly recognized as an important process involved in the chloroplast redox poise. Emerging literature suggests that alterations of energy management pathways affect not only cell fitness and survival, but also influence biomass content and composition. These emerging discoveries are important steps towards diverting algal photosynthetic energy to useful products for biotechnological applications.
Published: 2019
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6. A forward genetic approach in Chlamydomonas reinhardtii as a strategy for exploring starch catabolism.

Author: Hande Tunçay, Justin Findinier, Thierry Duchêne, Virginie Cogez, Charlotte Cousin, Gilles Peltier, Steven G Ball, and David Dauvillée
Subjects: Medicine, Science
Abstract: A screen was recently developed to study the mobilization of starch in the unicellular green alga Chlamydomonas reinhardtii. This screen relies on starch synthesis accumulation during nitrogen starvation followed by the supply of nitrogen and the switch to darkness. Hence multiple regulatory networks including those of nutrient starvation, cell cycle control and light to dark transitions are likely to impact the recovery of mutant candidates. In this paper we monitor the specificity of this mutant screen by characterizing the nature of the genes disrupted in the selected mutants. We show that one third of the mutants consisted of strains mutated in genes previously reported to be of paramount importance in starch catabolism such as those encoding β-amylases, the maltose export protein, and branching enzyme I. The other mutants were defective for previously uncharacterized functions some of which are likely to define novel proteins affecting starch mobilization in green algae.
Published: 2013
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7. Energy crosstalk between photosynthesis and the algal CO2-concentrating mechanisms

Author: Adrien Burlacot and Gilles Peltier
Subjects: Plant Science
Published: 2023

8. Autocatalytic effect boosts the production of medium-chain hydrocarbons by fatty acid photodecarboxylase

Author: Poutoum P. Samire, Bo Zhuang, Bertrand Légeret, Ángel Baca-Porcel, Gilles Peltier, Damien Sorigué, Alexey Aleksandrov, Frédéric Beisson, Pavel Müller, Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire d'Optique et Biosciences (LOB), École polytechnique (X)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Institut de Biologie Intégrative de la Cellule (I2BC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Département Biochimie, Biophysique et Biologie Structurale (B3S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), China Scholarship Council, ANR-18-CE11-0021,SNAPsHOTs,Dynamique structurale de l'acide gras photodécarboxylase(2018), ANR-18-CE43-0008,PHOTOALKANE,Production biosourcée d'hydrocarbures basée sur une nouvelle photoenzyme(2018), and ANR-18-CE44-0002,ATMCADD,Modèles atomiques précis pour la conception de médicaments assistée par ordinateur(2018)
Subjects: Multidisciplinary, [SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology, [CHIM.CATA]Chemical Sciences/Catalysis
Abstract: Ongoing climate change is driving the search for renewable and carbon-neutral alternatives to fossil fuels. Photocatalytic conversion of fatty acids to hydrocarbons by fatty acid photodecarboxylase (FAP) represents a promising route to green fuels. However, the alleged low activity of FAP on C2 to C12 fatty acids seemed to preclude the use for synthesis of gasoline-range hydrocarbons. Here, we reveal that Chlorella variabilis FAP ( Cv FAP) can convert n -octanoic acid in vitro four times faster than n -hexadecanoic acid, its best substrate reported to date. In vivo, this translates into a Cv FAP-based production rate over 10-fold higher for n -heptane than for n -pentadecane. Time-resolved spectroscopy and molecular modeling demonstrate that Cv FAP’s high catalytic activity on n -octanoic acid is, in part, due to an autocatalytic effect of its n -heptane product, which fills the rest of the binding pocket. These results represent an important step toward a bio-based and light-driven production of gasoline-like hydrocarbons.
Published: 2023

9. Cyclic and pseudo-cyclic electron pathways play antagonistic roles during nitrogen deficiency in Chlamydomonas reinhardtii

Author: Ousmane Dao, Adrien Burlacot, Marie Huleux, Pascaline Auroy, Gilles Peltier, Yonghua Li-Beisson, Environnement, Bioénergie, Microalgues et Plantes (EBMP), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Laboratoire d'Ecologie Microbienne de la Rhizosphère et d'Environnements Extrêmes (LEMIRE)
Subjects: [SDV]Life Sciences [q-bio]
Abstract: Nitrogen (N) deficiency is a frequently encountered situation that constrains global biomass productivity. In response to N deficiency, cell division stops and photosynthetic electron transfer are downregulated, while carbon storage is enhanced. However, the molecular mechanism downregulating photosynthesis during N deficiency and its relationship with carbon storage are not fully understood. The Proton Gradient Regulator-like 1 (PGRL1)-involved in cyclic electron flow (CEF) and Flavodiiron proteins involved in pseudo-(CEF) are major players in the acclimation of photosynthesis. To determine the role of PGRL1 or FLV in photosynthesis under N deficiency, we measured photosynthetic electron transfer, oxygen gas exchange and carbon storage in the knockout of Chlamydomonaspgrl1 and flvBmutants. Under N deficiency,pgrl1maintains higher net photosynthesis and O2photoreduction rates, whileflvBshows similar responses compared to control strains. The amount of cytochromeb6fwas maintained at a higher level inpgrl1. The photosynthetic activity ofpgrl1 flvBdouble mutants decreases in response to N deficiency similar to the control strains. Furthermore, the triacylglycerol content ofpgrl1was twice higher than the controls under N deficiency. Taken together, our results suggest that in the absence of PGRL1, FLV-mediated O2photoreduction through PCEF maintains net photosynthesis at a high level, resulting in increased triacylglycerol biosynthesis. This study reveals that PGRL1 and FLV play antagonistic roles during N deficiency. It further illustrates how nutrient status can affect the regulation of photosynthetic energy production in relation to carbon storage and provides new strategies for improving lipid productivity in algae.Significance statementNitrogen (N) deficiency, an often-encountered phenomenon in nature, triggers growth arrest and massive lipid accumulation in microalgae. The downregulation of photosynthesis is necessary to ensure cell viability. We demonstrate that a well-conserved protein in chlorophytes, the Proton Gradient Regulator-like 1 (PGRL1) is a key (down) regulator of photosynthesis. In its absence, cells exhibited sustained photosynthesis and over-accumulated lipids thanks to the Flavodiiron (FLV) protein. We propose that both PGRL1 and FLV, by having antagonistic roles in N deficiency, manage the redox landscape, carbon storage and biomass production. Our work revolves around the current paradigm of photosynthesis regulation during N deficiency and provides a new framework for improving lipid accumulation in microalgae for biotechnological purposes.
Published: 2023

10. Role of an ancient light-harvesting protein of PSI in light absorption and photoprotection

Author: Anastasios Melis, Thien Crisanto, Hiroko Takahashi, Alessandro Alboresi, Krishna K. Niyogi, Tomas Morosinotto, Adrien Burlacot, Oliver Dautermann, Masakazu Iwai, Gilles Peltier, Qinhua Gan, Yandu Lu, Environnement, Bioénergie, Microalgues et Plantes (EBMP), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Bioénergie et Microalgues (EBM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Photosystem I, 0106 biological sciences, 0301 basic medicine, Light, [SDV]Life Sciences [q-bio], Mutant, photosystem, General Physics and Astronomy, 01 natural sciences, antenna, chemistry.chemical_compound, Nannochloropsis, Photosynthesis, Multidisciplinary, biology, Endosymbiosis, Chemistry, light-harvesting, Adaptation, Physiological, Cell biology, Antenna complex, Stramenopiles, Physiological, 1.1 Normal biological development and functioning, Science, Article, General Biochemistry, Genetics and Molecular Biology, 03 medical and health sciences, Algae, Underpinning research, Light responses, Adaptation, photosynthesis, Photosystem I Protein Complex, Chlorophyll A, Wild type, General Chemistry, light-harvesting, Nannochloropsis, photoprotection, photosystem, photosynthesis, antenna, biology.organism_classification, photoprotection, 030104 developmental biology, Chlorophyll, Photoprotection, Mutation, Generic health relevance, Chlorophyll Binding Proteins, Function (biology), 010606 plant biology & botany
Abstract: Diverse algae of the red lineage possess chlorophyll a-binding proteins termed LHCR, comprising the PSI light-harvesting system, which represent an ancient antenna form that evolved in red algae and was acquired through secondary endosymbiosis. However, the function and regulation of LHCR complexes remain obscure. Here we describe isolation of a Nannochloropsis oceanica LHCR mutant, named hlr1, which exhibits a greater tolerance to high-light (HL) stress compared to the wild type. We show that increased tolerance to HL of the mutant can be attributed to alterations in PSI, making it less prone to ROS production, thereby limiting oxidative damage and favoring growth in HL. HLR1 deficiency attenuates PSI light-harvesting capacity and growth of the mutant under light-limiting conditions. We conclude that HLR1, a member of a conserved and broadly distributed clade of LHCR proteins, plays a pivotal role in a dynamic balancing act between photoprotection and efficient light harvesting for photosynthesis., LHCR proteins are ancient chlorophyll a-binding antennas that evolved in diverse algae of the red lineage. Here Lu et al. characterize a red lineage LHCR mutant and show reduced oxidative damage in high light but attenuated growth under low light, thus demonstrating how LHCR proteins impact the balance between photoprotection and light harvesting.
Published: 2021

11. Boosting chloroplast ribosome biogenesis by a plastidial DEAD-box RNA helicase is critical for high light acclimation

Author: El Batoul Djouani-Tahri, Sreedhar Nellaepalli, Pascaline Auroy, Emmanuelle Billon, Adrien Burlacot, Frédéric Chaux-Jukic, Stéphan Cuiné, Virginie Epting, Marie Huleux, Bart Ghysels, Miriam Schulz-Raffelt, Isabelle Te, Sabine Brugière, Yohann Couté, Yuichiro Takahashi, Yonghua Li-Beisson, and Gilles Peltier
Abstract: Photosynthetic organisms have developed sophisticated strategies to fine-tune light energy conversion to meet the metabolic demand, thereby optimizing growth in fluctuating light environments. Although mechanisms such as energy dissipation, photosynthetic control, or the photosystem II (PSII) damage and repair have been widely studied, little is known about the regulation of protein synthesis capacity during light acclimation. By screening a Chlamydomonas reinhardtii insertional mutant library using chlorophyll fluorescence imaging, we isolated a high chlorophyll fluorescence mutant (hf0) defected in a gene encoding a putative plastid targeted DEAD-box RNA helicase called CreRH22. CreRH22 is rapidly induced upon illumination and belongs to the GreenCut, a set of proteins specific to photosynthetic organisms. While photosynthesis is slightly affected in the mutant under low light (LL), exposure to high light (HL) induces a marked decrease in both PSII and PSI, and a strong alteration of the light-induced gene expression pattern. These effects are explained by the inability of hf0 to increase plastid ribosome amounts under HL. We conclude that CreRH22, by promoting ribosomal RNA precursor maturation in a light-dependent manner, enables the assembly of extra-ribosomes required to synthesize photosystem subunits at a higher rate, a critical step in the acclimation of algae to HL.
Published: 2022

12. Alternative photosynthesis pathways drive the algal CO2-concentrating mechanism

Author: Adrien Burlacot, Ousmane Dao, Pascaline Auroy, Stephan Cuiné, Yonghua Li-Beisson, Gilles Peltier, Environnement, Bioénergie, Microalgues et Plantes (EBMP), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
Subjects: Multidisciplinary, [SDV]Life Sciences [q-bio]
Abstract: International audience; Global photosynthesis consumes ten times more CO2 than net anthropogenic emissions, and microalgae account for nearly half of this consumption1. The high efficiency of algal photosynthesis relies on a mechanism concentrating CO2 (CCM) at the catalytic site of the carboxylating enzyme RuBisCO, which enhances CO2 fixation2. Although many cellular components involved in the transport and sequestration of inorganic carbon have been identified3,4, how microalgae supply energy to concentrate CO2 against a thermodynamic gradient remains unknown4–6. Here we show that in the green alga Chlamydomonas reinhardtii, the combined action of cyclic electron flow and O2 photoreduction—which depend on PGRL1 and flavodiiron proteins, respectively—generate a low luminal pH that is essential for CCM function. We suggest that luminal protons are used downstream of thylakoid bestrophin-like transporters, probably for the conversion of bicarbonate to CO2. We further establish that an electron flow from chloroplast to mitochondria contributes to energizing non-thylakoid inorganic carbon transporters, probably by supplying ATP. We propose an integrated view of the network supplying energy to the CCM, and describe how algal cells distribute energy from photosynthesis to power different CCM processes. These results suggest a route for the transfer of a functional algal CCM to plants to improve crop productivity.
Published: 2022

13. Physiological functions of malate shuttles in plants and algae

Author: Yonghua Li-Beisson, Andreas P.M. Weber, Ousmane Dao, Franziska Kuhnert, Gilles Peltier, Environnement, Bioénergie, Microalgues et Plantes (EBMP), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Heinrich Heine Universität Düsseldorf = Heinrich Heine University [Düsseldorf], Bioénergie et Microalgues (EBM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, [SDV]Life Sciences [q-bio], Malates, Plant Science, Biology, Photosynthesis, 01 natural sciences, Malate dehydrogenase, Redox, 03 medical and health sciences, Citrate synthase, 030304 developmental biology, chemistry.chemical_classification, 0303 health sciences, Fatty acid, food and beverages, Metabolic intermediate, NAD, chemistry, Biochemistry, biology.protein, Photorespiration, NAD+ kinase, Oxidation-Reduction, 010606 plant biology & botany
Abstract: Subcellular compartmentalization confers evolutionary advantage to eukaryotic cells but entails the need for efficient interorganelle communication. Malate functions as redox carrier and metabolic intermediate. It can be shuttled across membranes through translocators. The interconversion of malate and oxaloacetate mediated by malate dehydrogenases requires oxidation/reduction of NAD(P)H/NAD(P)+; therefore, malate trafficking serves to transport reducing equivalents and this is termed the ‘malate shuttle’. Although the term 'malate shuttle' was coined more than 50 years ago, novel functions are still emerging. This review highlights recent findings on the functions of malate shuttles in photorespiration, fatty acid β-oxidation, interorganelle signaling and its putative role in CO2-concentrating mechanisms. We compare and contrast knowledge in plants and algae, thereby providing an evolutionary perspective on redox trafficking in photosynthetic eukaryotes.
Published: 2021

14. Alternative electron pathways of photosynthesis drive the algal CO 2 concentrating mechanism

Author: Yonghua Li-Beisson, Gilles Peltier, Ousmane Dao, Adrien Burlacot, Stéphan Cuiné, Pascaline Auroy, Environnement, Bioénergie, Microalgues et Plantes (EBMP), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Bioénergie et Microalgues (EBM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, 0303 health sciences, biology, Chemiosmosis, Chemistry, [SDV]Life Sciences [q-bio], Chlamydomonas, RuBisCO, Photosynthesis, biology.organism_classification, 01 natural sciences, 03 medical and health sciences, Total inorganic carbon, Mechanism (philosophy), Thylakoid, biology.protein, Biophysics, Chlorophyll fluorescence, 030304 developmental biology, 010606 plant biology & botany
Abstract: Global photosynthesis consumes ten times more CO2 than net anthropogenic emissions, and microalgae account for nearly half of this consumption1. The great efficiency of algal photosynthesis relies on a mechanism concentrating CO2 (CCM) at the catalytic site of the carboxylating enzyme RuBisCO, thus enhancing CO2 fixation2. While many cellular components involved in the transport and sequestration of inorganic carbon (Ci) have been uncovered3,4, the way microalgae supply energy to concentrate CO2 against a thermodynamic gradient remains elusive4-6. Here, by monitoring dissolved CO2 consumption, unidirectional O2 exchange and the chlorophyll fluorescence parameter NPQ in the green alga Chlamydomonas, we show that the complementary effects of cyclic electron flow and O2 photoreduction, respectively mediated by PGRL1 and flavodiiron proteins, generate the proton motive force (pmf) required by Ci transport across thylakoid membranes. We demonstrate that the trans-thylakoid pmf is used by bestrophin-like Ci transporters and further establish that a chloroplast-to-mitochondria electron flow contributes to energize non-thylakoid Ci transporters, most likely by supplying ATP. We propose an integrated view of the CCM energy supply network, describing how algal cells distribute photosynthesis energy to power different Ci transporters, thus paving the way to the transfer of a functional algal CCM in plants towards improving crop productivity.One sentence summaryPhotosynthetic alternative electron flows and mitochondrial respiration drive the algal CO2 concentrating mechanism
Published: 2021

15. Mechanism and dynamics of fatty acid photodecarboxylase

Author: Sébastien Boutet, Catherine Berthomieu, Laura Antonucci, A. Gorel, Manuel Joffre, Marco Cammarata, A. Benachir, Sergio Carbajo, Solène L. Y. Moulin, Martin Weik, Michel Sliwa, Stephane Cuine, Yonghua Li-Beisson, Nicolas Coquelle, Didier Nurizzo, P. Samire, Jacques-Philippe Colletier, Alexey Aleksandrov, Robert L. Shoeman, Guillaume Gotthard, Antoine Royant, Marten H. Vos, Bo Zhuang, M. Hilpert, Adeline Bonvalet, Ilme Schlichting, Xavier Solinas, Martin Byrdin, Pascal Arnoux, Gilles Peltier, Pierre Legrand, F. Beisson, Klaus Brettel, R. Hienerwadel, Thomas R. M. Barends, R.B. Doak, Lutz Foucar, T. Domratcheva, Damien Sorigué, Marco Kloos, Stéphanie Blangy, Giorgio Schirò, Kyprianos Hadjidemetriou, Bertrand Légeret, Thomas J. Lane, Marie Luise Grünbein, Pavel Müller, Elisabeth Hartmann, Environnement, Bioénergie, Microalgues et Plantes (EBMP), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut de biologie structurale (IBS - UMR 5075), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), European Synchroton Radiation Facility [Grenoble] (ESRF), Laboratoire d'Optique et Biosciences (LOB), École polytechnique (X)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Institut Laue-Langevin (ILL), Institut de Biologie Intégrative de la Cellule (I2BC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), SLAC National Accelerator Laboratory (SLAC), Stanford University, Institut de Physique de Rennes (IPR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Medizinische Forschung, Max-Planck-Gesellschaft, Luminy Génétique et Biophysique des Plantes (LGBP), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Laboratoire Avancé de Spectroscopie pour les Intéractions la Réactivité et l'Environnement - UMR 8516 (LASIRE), Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Interactions Protéine Métal (IPM), Department of Chemistry, Lomonosov Moscow State University, Lomonosov Moscow State University (MSU), Microbiologie Environnementale et Moléculaire (MEM), STepLADDER (724362), European Research Council, 724362, European Research Council, SNAPsHOTs, Agence Nationale de la Recherche, Photoalkane, Agence Nationale de la Recherche, SignalBioNRJ, Agence Nationale de la Recherche, BioXFEL, Agence Nationale de la Recherche, Ministère de l’Education Nationale, de l’Enseignement Supérieur et de la Recherche, ANR-10-INBS-0005,FRISBI,Infrastructure Française pour la Biologie Structurale Intégrée(2010), ANR-18-CE11-0021,SNAPsHOTs,Dynamique structurale de l'acide gras photodécarboxylase(2018), ANR-18-CE43-0008,PHOTOALKANE,Production biosourcée d'hydrocarbures basée sur une nouvelle photoenzyme(2018), ANR-15-CE32-0004,BioXFEL,Caractérisation d'états intermédiaires de protéines fluorescentes en utilisant des lasers à électrons libres X et les spectroscopies UV-visible et infrarouge ultra-rapides(2015), European Project: 724362,STePLADDER - H2020-EU.1.1., Bioénergie et Microalgues (EBM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), ILL, Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Centrale Lille Institut (CLIL), Vos, Marten, Infrastructure Française pour la Biologie Structurale Intégrée - - FRISBI2010 - ANR-10-INBS-0005 - INBS - VALID, APPEL À PROJETS GÉNÉRIQUE 2018 - Dynamique structurale de l'acide gras photodécarboxylase - - SNAPsHOTs2018 - ANR-18-CE11-0021 - AAPG2018 - VALID, APPEL À PROJETS GÉNÉRIQUE 2018 - Production biosourcée d'hydrocarbures basée sur une nouvelle photoenzyme - - PHOTOALKANE2018 - ANR-18-CE43-0008 - AAPG2018 - VALID, Caractérisation d'états intermédiaires de protéines fluorescentes en utilisant des lasers à électrons libres X et les spectroscopies UV-visible et infrarouge ultra-rapides - - BioXFEL2015 - ANR-15-CE32-0004 - AAPG2015 - VALID, and Solving The Pathway of LADDERane biosynthesis - STePLADDER - H2020-EU.1.1. - 724362 - INCOMING
Subjects: Models, Molecular, Light, Carboxy-Lyases, Protein Conformation, Decarboxylation, Chlorella, Reaction intermediate, Flavin group, Crystallography, X-Ray, 010402 general chemistry, Photochemistry, 01 natural sciences, [PHYS] Physics [physics], Electron Transport, 03 medical and health sciences, Catalytic Domain, Alkanes, [SDV.BBM] Life Sciences [q-bio]/Biochemistry, Molecular Biology, [SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology, Amino Acids, Alkyl, 030304 developmental biology, chemistry.chemical_classification, [PHYS]Physics [physics], Photons, 0303 health sciences, Multidisciplinary, Algal Proteins, Fatty Acids, Temperature, Fatty acid, Substrate (chemistry), Hydrogen Bonding, Carbon Dioxide, Chromophore, Electron transport chain, 0104 chemical sciences, Bicarbonates, Amino Acid Substitution, chemistry, 13. Climate action, Biocatalysis, Flavin-Adenine Dinucleotide, Mutant Proteins, Oxidation-Reduction
Abstract: Light makes light work of fatty acids Photosynthetic organisms are notable for their ability to capture light energy and use it to power biosynthesis. Some algae have gone a step beyond photosynthesis and can use light to initiate enzymatic photodecarboxylation of fatty acids, producing long-chain hydrocarbons. To understand this transformation, Sorigué et al. brought to bear an array of structural, computational, and spectroscopic techniques and fully characterized the catalytic cycle of the enzyme. These experiments are consistent with a mechanism starting with electron transfer from the fatty acid to a photoexcited oxidized flavin cofactor. Decarboxylation yields an alkyl radical, which is then reduced by back electron transfer and protonation rather than hydrogen atom transfer. The wealth of experimental data explains how algae harness light energy to produce alka(e)nes and provides an appealing model system for understanding enzyme-catalyzed photochemistry more generally. Science , this issue p. eabd5687
Published: 2021

16. Alternative photosynthesis pathways drive the algal CO

Author: Adrien, Burlacot, Ousmane, Dao, Pascaline, Auroy, Stephan, Cuiné, Yonghua, Li-Beisson, and Gilles, Peltier
Subjects: Chloroplasts, Carbon Dioxide, Photosynthesis, Carbon, Chlamydomonas reinhardtii
Abstract: Global photosynthesis consumes ten times more CO
Published: 2021

17. Fatty acid photodecarboxylase is an ancient photoenzyme that forms hydrocarbons in the thylakoids of algae

Author: Bertrand Légeret, Damien Sorigué, Magali Floriani, Adrien Burlacot, Stéphan Cuiné, Audrey Beyly-Adriano, Stéphanie Blangy, Fred Beisson, Poutoum-Palakiyem Samire, Solène L. Y. Moulin, Gilles Peltier, Yonghua Li-Beisson, Bioénergie et Microalgues (EBM), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'écotoxicologie des radionucléides (PRP-ENV/SERIS/LECO), Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Environnement, Bioénergie, Microalgues et Plantes (EBMP), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire d'écotoxicologie des radionucléides (IRSN/PRP-ENV/SERIS/LECO), Service de Recherche et d'Expertise sur les Risques environnementaux (IRSN/PRP-ENV/SERIS), Institut de Radioprotection et de Sûreté Nucléaire (IRSN)-Institut de Radioprotection et de Sûreté Nucléaire (IRSN), and ANR-18-CE43-0008,PHOTOALKANE,Production biosourcée d'hydrocarbures basée sur une nouvelle photoenzyme(2018)
Subjects: 0106 biological sciences, congenital, hereditary, and neonatal diseases and abnormalities, Genotype, Light, Carboxy-Lyases, Physiology, Chlamydomonas reinhardtii, Plant Science, Genes, Plant, Thylakoids, 01 natural sciences, 03 medical and health sciences, Algae, Gene Expression Regulation, Plant, Microalgae, Genetics, Cold acclimation, Plastid, [SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biochemistry [q-bio.BM], neoplasms, Research Articles, 030304 developmental biology, 0303 health sciences, biology, Endosymbiosis, Chemistry, Fatty Acids, Genetic Variation, Ectocarpus, [SDV.BV.BOT]Life Sciences [q-bio]/Vegetal Biology/Botanics, Photochemical Processes, biology.organism_classification, digestive system diseases, Light intensity, Biochemistry, Mutation, Nannochloropsis, 010606 plant biology & botany
Abstract: Fatty acid photodecarboxylase (FAP) is one of the few enzymes that require light for their catalytic cycle (photoenzymes). FAP was first identified in the microalga Chlorella variabilis NC64A, and belongs to an algae-specific subgroup of the glucose–methanol–choline oxidoreductase family. While the FAP from C. variabilis and its Chlamydomonas reinhardtii homolog CrFAP have demonstrated in vitro activities, their activities and physiological functions have not been studied in vivo. Furthermore, the conservation of FAP activity beyond green microalgae remains hypothetical. Here, using a C. reinhardtii FAP knockout line (fap), we showed that CrFAP is responsible for the formation of 7-heptadecene, the only hydrocarbon of this alga. We further showed that CrFAP was predominantly membrane-associated and that >90% of 7-heptadecene was recovered in the thylakoid fraction. In the fap mutant, photosynthetic activity was not affected under standard growth conditions, but was reduced after cold acclimation when light intensity varied. A phylogenetic analysis that included sequences from Tara Ocean identified almost 200 putative FAPs and indicated that FAP was acquired early after primary endosymbiosis. Within Bikonta, FAP was retained in secondary photosynthetic endosymbiosis lineages but absent from those that lost the plastid. Characterization of recombinant FAPs from various algal genera (Nannochloropsis, Ectocarpus, Galdieria, Chondrus) provided experimental evidence that FAP photochemical activity was present in red and brown algae, and was not limited to unicellular species. These results thus indicate that FAP was conserved during the evolution of most algal lineages where photosynthesis was retained, and suggest that its function is linked to photosynthetic membranes.
Published: 2021

18. Corrigendum: Membrane Inlet Mass Spectrometry: A Powerful Tool for Algal Research

Author: François Burlacot, Adrien Burlacot, Yonghua Li-Beisson, and Gilles Peltier
Subjects: Cyanobacteria, geography, geography.geographical_feature_category, Chromatography, photosynthesis, biology, Chemistry, carbonic anhydrase, O2 evolution, Plant Science, gas exchange, lcsh:Plant culture, Photosynthesis, Inlet, biology.organism_classification, Mass spectrometry, Membrane, Carbonic anhydrase, biology.protein, CO2 concentrating mechanism, lcsh:SB1-1110, H2 production
Published: 2020

19. Fatty acid photodecarboxylase is an ancient photoenzyme responsible for hydrocarbon formation in the thylakoid membranes of algae

Author: Gilles Peltier, Adrien Burlacot, Solène L. Y. Moulin, Stéphanie Blangy, F. Beisson, Yonghua Li-Beisson, Audrey Beyly, Damien Sorigué, Bertrand Légeret, and Magali Floriani
Subjects: Chlorella, biology, Biochemistry, Algae, Chemistry, Chlamydomonas, Cold acclimation, Chlamydomonas reinhardtii, Green algae, Ectocarpus, Plastid, biology.organism_classification
Abstract: Fatty acid photodecarboxylase (FAP) is one of the three enzymes that require light for their catalytic cycle (photoenzymes). FAP has been first identified in the green microalga Chlorella variabilis NC64A and belongs an algae-specific subgroup of the glucose-methanol-choline oxidoreductase family. While the FAP from Chlorella and its Chlamydomonas reinhardtii homolog CrFAP have demonstrated in vitro activity, their activity and physiological function have not been studied in vivo. Besides, the conservation of FAP activity beyond green microalgae remains hypothetical. Here, using a Chlamydomonas FAP knockout line (fap), we show that CrFAP is responsible for the formation of 7-heptadecene, the only hydrocarbon present in this alga. We further show that CrFAP is associated to the thylakoids and that 90% of 7-heptadecene is recovered in this cell fraction. In the fap mutant, photosynthesis activity was not affected under standard growth conditions but was reduced after cold acclimation. A phylogenetic analysis including sequences from Tara Ocean identified almost 200 putative FAPs and indicated that FAP was acquired early after primary endosymbiosis. Within Bikonta, FAP was kept in photosynthetic secondary endosymbiosis lineages but absent in those that lost the plastid. Characterization of recombinant FAPs from various algal genera (Nannochloropsis, Ectocarpus, Galdieria, Chondrus) provided experimental evidence that FAP activity is conserved in red and brown algae and is not limited to unicellular species. These results thus indicate that FAP has been conserved during evolution of most algal lineages when photosynthesis was kept and suggest that its function is linked to photosynthetic membranes.One sentence summaryFAP is present in thylakoids and conserved beyond green algae.
Published: 2020

20. Membrane inlet mass spectrometry at the crossroads of photosynthesis, biofuel and climate research

Author: Adrien Burlacot, Gilles Peltier, Yonghua Li-Beisson, Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Environnement, Bioénergie, Microalgues et Plantes (EBMP), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), and Bioénergie et Microalgues (EBM)
Subjects: 0106 biological sciences, geography, geography.geographical_feature_category, Physiology, Climate, Plant Science, Inlet, Photosynthesis, Mass spectrometry, 7. Clean energy, 01 natural sciences, Mass Spectrometry, [SDV.BV.AP]Life Sciences [q-bio]/Vegetal Biology/Plant breeding, Membrane, 13. Climate action, Biofuel, Biofuels, Environmental chemistry, Genetics, Letters, 010606 plant biology & botany
Abstract: International audience; Microalgae are continuously shaping Earth’s atmosphere through oxygenic photosynthesis, and nowadays, half of the photosynthesis is attributed to microbial photosynthesis (Field et al., 1998; Behrenfeld et al., 2005). While algal photosynthesis contributes to offsetting the CO2 footprint, it also produces nitric oxide (N2O), a potent greenhouse gas. In some ecological niches microalgae can produce hydrogen (H2), a promising energy carrier; therefore microalgae are actively explored for their potential as a platform for production of renewable energy. Measuring gas exchange between algae and the atmosphere, and understanding biological mechanisms underlying photosynthetic CO2 capture, and O2, H2, or N2O production, holds great promise—not only to better evaluate the reciprocal effects of global changes on oceanic carbon sinks, but also to explore the limits of biomass and biofuel productivity of algae. Membrane inlet mass spectrometry (MIMS) was initially developed to measure O2 exchange between algal cells and the surrounding liquid medium (Hoch and Kok, 1963), and its use has since been extended to other gases including H2 and more recently, N2O (Burlacot et al., 2020). Here we review recent breakthroughs allowed by MIMS in dissecting molecular mechanisms of gas exchange in microalgae (Fig. 1) and provide perspectives on how MIMS will be crucial to address future challenges in algal research.
Published: 2020

21. ACCLIMATION OF PHOTOSYNTHESIS TO THE ENVIRONMENT 1 regulates Photosystem II Supercomplex dynamics in response to light in Chlamydomonas reinhardtii

Author: Pawel Brzezowski, Marie Chazaux, Magali Floriani, Gilles Peltier, Stefano Caffarri, Xenie Johnson, Jean Alric, Juliane da Graça, Bernard Genty, Stéphan Cuiné, Photosynthèse & Environnement (P&E), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Biologie végétale et microbiologie environnementale - UMR7265 (BVME), Laboratoire d'écotoxicologie des radionucléides (IRSN/PSE-ENV/SRTE/LECO), Service de recherche sur les transferts et les effets des radionucléides sur les écosystèmes (IRSN/PSE-ENV/SRTE), Institut de Radioprotection et de Sûreté Nucléaire (IRSN)-Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Aix Marseille Université (AMU), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Institut de Radioprotection et de Sûreté Nucléaire (IRSN), and PSE-ENV/SRTE/LECO
Subjects: 0106 biological sciences, 0303 health sciences, Photoinhibition, biology, Phototroph, Photosystem II, Chemistry, [SDV]Life Sciences [q-bio], Chlamydomonas, Chlamydomonas reinhardtii, food and beverages, macromolecular substances, biology.organism_classification, Photosynthesis, 01 natural sciences, Acclimatization, 03 medical and health sciences, Thylakoid, Biophysics, 030304 developmental biology, 010606 plant biology & botany
Abstract: Photosynthetic organisms require acclimation mechanisms to regulate photosynthesis in response to light conditions. Here, two mutant alleles of ACCLIMATION OF PHOTOSYNTHESIS TO THE ENVIRONMENT 1 (ape1) have been characterized in Chlamydomonas reinhardtii. The ape1 mutants are photosensitive and show PSII photoinhibition during high light acclimation or under high light stress. The ape1 mutants retain more PSII super-complexes and have changes to thylakoid stacking relative to control strains during photosynthetic growth at different light intensities. The APE1 protein is found in all oxygenic phototrophs and encodes a 25 kDa thylakoid protein that interacts with the Photosystem II core complex as monomers, dimers and supercomplexes. We propose a model where APE1 bound to PSII supercomplexes releases core complexes and promotes PSII heterogeneity influencing the stacking of Chlamydomonas thylakoids. APE1 is a regulator in light acclimation and its function is to reduce over-excitation of PSII centres and avoid PSII photoinhibition to increase the resilience of photosynthesis to high light.
Published: 2020
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22. Continuous photoproduction of hydrocarbon drop-in fuel by microbial cell factories

Author: Yonghua Li-Beisson, Gilles Peltier, Stéphanie Blangy, Adrien Burlacot, Damien Sorigué, Fred Beisson, Pascaline Auroy, Bertrand Légeret, Solène L. Y. Moulin, Environnement, Bioénergie, Microalgues et Plantes (EBMP), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Programme CEA DRF Impulsion Invention, Alcasun, HelioBiotec platform funded by the EU, the région PACA, the French Ministry of Research, and the CEA, ANR-18-CE43-0008,PHOTOALKANE,Production biosourcée d'hydrocarbures basée sur une nouvelle photoenzyme(2018), Burlacot, Adrien, APPEL À PROJETS GÉNÉRIQUE 2018 - Production biosourcée d'hydrocarbures basée sur une nouvelle photoenzyme - - PHOTOALKANE2018 - ANR-18-CE43-0008 - AAPG2018 - VALID, Bioénergie et Microalgues (EBM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, 0301 basic medicine, [SDV.BIO]Life Sciences [q-bio]/Biotechnology, Light, lcsh:Medicine, 01 natural sciences, 7. Clean energy, Continuous production, Article, 03 medical and health sciences, Key point, Thioesterase, Continuous release, Escherichia coli, Microalgae, lcsh:Science, chemistry.chemical_classification, Multidisciplinary, Drop (liquid), lcsh:R, Fatty Acids, Fatty acid, Pulp and paper industry, Hydrocarbons, Enzymes, [SDV.BIO] Life Sciences [q-bio]/Biotechnology, 030104 developmental biology, Hydrocarbon, chemistry, Biofuels, lcsh:Q, Volatility (chemistry), Metabolic engineering, 010606 plant biology & botany
Abstract: Use of microbes to produce liquid transportation fuels is not yet economically viable. A key point to reduce production costs is the design a cell factory that combines the continuous production of drop-in fuel molecules with the ability to recover products from the cell culture at low cost. Medium-chain hydrocarbons seem ideal targets because they can be produced from abundant fatty acids and, due to their volatility, can be easily collected in gas phase. However, pathways used to produce hydrocarbons from fatty acids require two steps, low efficient enzymes and/or complex electron donors. Recently, a new hydrocarbon-forming route involving a single enzyme called fatty acid photodecarboxylase (FAP) was discovered in microalgae. Here, we show that in illuminated E. coli cultures coexpression of FAP and a medium-chain fatty acid thioesterase results in continuous release of volatile hydrocarbons. Maximum hydrocarbon productivity was reached under low/medium light while higher irradiance resulted in decreased amounts of FAP. It was also found that the production rate of hydrocarbons was constant for at least 5 days and that 30% of total hydrocarbons could be collected in the gas phase of the culture. This work thus demonstrates that the photochemistry of the FAP can be harnessed to design a simple cell factory that continuously produces hydrocarbons easy to recover and in pure form.
Published: 2019

23. Flavodiiron-Mediated O2 Photoreduction Links H2 Production with CO2 Fixation during the Anaerobic Induction of Photosynthesis

Author: Gilles Peltier, Pascaline Auroy-Tarrago, Adrien Burlacot, Stéphanie Blangy, Thomas Happe, Stéphan Cuiné, Anne Sawyer, Bioénergie et Microalgues (EBM), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU), Biologie végétale et microbiologie environnementale - UMR7265 (BVME), Ruhr-Universität Bochum [Bochum], Environnement, Bioénergie, Microalgues et Plantes (EBMP), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
Subjects: 0106 biological sciences, 0301 basic medicine, chemistry.chemical_classification, Hydrogenase, biology, Photosystem II, Physiology, Chemistry, Carbon fixation, Chlamydomonas reinhardtii, Plant Science, Electron acceptor, biology.organism_classification, Photosystem I, Photosynthesis, 01 natural sciences, [SDV.BV.AP]Life Sciences [q-bio]/Vegetal Biology/Plant breeding, 03 medical and health sciences, 030104 developmental biology, Genetics, Biophysics, Chlorophyll fluorescence, 010606 plant biology & botany
Abstract: International audience; Some microalgae, such as Chlamydomonas reinhardtii, harbor a highly flexible photosynthetic apparatus capable of using different electron acceptors, including carbon dioxide (CO2), protons, or oxygen (O2), allowing survival in diverse habitats. During anaerobic induction of photosynthesis, molecular O2 is produced at photosystem II, while at the photosystem I acceptor side, the reduction of protons into hydrogen (H2) by the plastidial [FeFe]-hydrogenases primes CO2 fixation. Although the interaction between H2 production and CO2 fixation has been extensively studied, their interplay with O2 produced by photosynthesis has not been considered. By simultaneously measuring gas exchange and chlorophyll fluorescence, we identified an O2 photoreduction mechanism that functions during anaerobic dark to light transitions, and demonstrate that flavodiiron proteins (Flvs) are the major players involved in light-dependent O2 uptake. We further show that Flv-mediated O2 uptake is critical for the rapid induction of CO2 fixation, but is not involved in the creation of the micro-oxic niches previously proposed to protect the [FeFe]-hydrogenase from O2. By studying a mutant lacking both hydrogenases (HYDA1 and HYDA2) and both Flvs (FLVA and FLVB), we show that the induction of photosynthesis is strongly delayed in the absence of both sets of proteins. Based on these data, we propose that Flvs are involved in an important intracellular O2 recycling process, which acts as a relay between H2 production and CO2 fixation.
Published: 2018

24. Algal photosynthesis converts nitric oxide into nitrous oxide

Author: Yonghua Li-Beisson, Arthur Gosset, Gilles Peltier, Pierre Richaud, Adrien Burlacot, Bioénergie et Microalgues (EBM), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), This work was supported by the ERA-SynBio project Sun2Chem., The authors acknowledge the European Union Regional Developing Fund, the Region Provence Alpes Côte d’Azur, the French Ministry of Research, and the CEA for funding the HelioBiotec platform., ANR-11-IDEX-0001,Amidex,INITIATIVE D'EXCELLENCE AIX MARSEILLE UNIVERSITE(2011), ANR-18-CE05-0029,OtolHyd,Hydrogénases cyanobactériennes tolérantes à l'Oxygène: caractérisation fonctionnelle et ingénierie(2018), Environnement, Bioénergie, Microalgues et Plantes (EBMP), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), ANR-18-CE05-0029,OTOLHYD,CYANOBACTERIAL OXYGEN-TOLERANT HYDROGENASES: FUNCTIONAL CHARACTERIZATION AND ENGINEERING(2018), and ANR-11-IDEX-0001-02/11-IDEX-0001,AMIDEX,AMIDEX(2011)
Subjects: 0301 basic medicine, 0106 biological sciences, flavodiiron, cytochrome P450, Plant Biology, Chlamydomonas reinhardtii, Nitric Oxide, Photosynthesis, 01 natural sciences, Nitric oxide, 03 medical and health sciences, chemistry.chemical_compound, Cytochrome P-450 Enzyme System, Algae, 14. Life underwater, Plant Proteins, 030304 developmental biology, 0303 health sciences, Multidisciplinary, photosynthesis, nitrous oxide, biology, Phototroph, microalgae, Aquatic ecosystem, Nitrous oxide, Biological Sciences, equipment and supplies, biology.organism_classification, Electron transport chain, [SDV.BV.AP]Life Sciences [q-bio]/Vegetal Biology/Plant breeding, Phototrophic Processes, 030104 developmental biology, chemistry, 13. Climate action, Environmental chemistry, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, [SDV.EE.BIO]Life Sciences [q-bio]/Ecology, environment/Bioclimatology, 010606 plant biology & botany
Abstract: Significance Nitrous oxide (N2O), the third most important greenhouse gas in the atmosphere, is produced in great quantities by microalgae, but molecular mechanisms remain elusive. Here we show that the green microalga Chlamydomonas reinhardtii produces N2O in the light by a reduction of NO driven by photosynthesis and catalyzed by flavodiiron proteins, the dark N2O production being catalyzed by a cytochrome p450. Both mechanisms of N2O production are present in chlorophytes, but absent from diatoms. Our study provides an unprecedented mechanistic understanding of N2O production by microalgae, allowing a better assessment of N2O-producing hot spots in aquatic environments., Nitrous oxide (N2O), a potent greenhouse gas in the atmosphere, is produced mostly from aquatic ecosystems, to which algae substantially contribute. However, mechanisms of N2O production by photosynthetic organisms are poorly described. Here we show that the green microalga Chlamydomonas reinhardtii reduces NO into N2O using the photosynthetic electron transport. Through the study of C. reinhardtii mutants deficient in flavodiiron proteins (FLVs) or in a cytochrome p450 (CYP55), we show that FLVs contribute to NO reduction in the light, while CYP55 operates in the dark. Both pathways are active when NO is produced in vivo during the reduction of nitrites and participate in NO homeostasis. Furthermore, NO reduction by both pathways is restricted to chlorophytes, organisms particularly abundant in ocean N2O-producing hot spots. Our results provide a mechanistic understanding of N2O production in eukaryotic phototrophs and represent an important step toward a comprehensive assessment of greenhouse gas emission by aquatic ecosystems.
Published: 2019

25. Chlamydomonas cell cycle mutant crcdc5 over-accumulates starch and oil

Author: Fantao Kong, Fred Beisson, Gilles Peltier, Bertrand Legeret, Ismael Torres-Romero, Yonghua Li-Beisson, Bioénergie et Microalgues (EBM), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), ANR-15-CE05-0021,SIGNAUXBIONRJ,Manipulation des voies de signalisation de l'énergie afin d'améliorer la production de .lipides chez les eucaryotes photosynthétiques(2015), Environnement, Bioénergie, Microalgues et Plantes (EBMP), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
Subjects: 0301 basic medicine, Algae, Cell division, Starch, [SDV]Life Sciences [q-bio], Mutant, Arabidopsis, Biomass, Gene Expression, Cell Cycle Proteins, Biochemistry, 03 medical and health sciences, chemistry.chemical_compound, Plant Oils, Protein Isoforms, ComputingMilieux_MISCELLANEOUS, 2. Zero hunger, 030102 biochemistry & molecular biology, biology, Chemistry, Arabidopsis Proteins, Mutants, Chlamydomonas, Algal Proteins, food and beverages, General Medicine, Cell cycle, biology.organism_classification, Oil, Carbon, Day/night cycle, Cell biology, 030104 developmental biology, Biofuel, Biofuels, Mutation, S Phase Cell Cycle Checkpoints, Cell Division, Chlamydomonas reinhardtii, Metabolic Networks and Pathways
Abstract: International audience; The use of algal biomass for biofuel production requires improvements in both biomass productivity and its energy density. Green microalgae store starch and oil as two major forms of carbon reserves. Current strategies to increase the amount of carbon reserves often compromise algal growth. To better understand the cellular mechanisms connecting cell division to carbon storage, we examined starch and oil accumulation in two Chlamydomonas mutants deficient in a gene encoding a homolog of the Arabidopsis Cell Division Cycle 5 (CDC5), a MYB DNA binding protein known to be involved in cell cycle in higher plants. The two crcdc5 mutants (crcdc5-1 and crcdc5-2) were found to accumulate significantly higher amount of starch and oil than their corresponding parental lines. Flow cytometry analysis on synchronized cultures cultivated in a diurnal light/dark cycle revealed an abnormal division of the two mutants, characterized by a prolonged S/M phase, therefore demonstrating its implication in cell cycle in Chlamydomonas. Taken together, these results suggest that the energy saved by a slowdown in cell division is used for the synthesis of reserve compounds. This work highlights the importance in understanding the interplay between cell cycle and starch/oil homeostasis, which should have a critical impact on improving lipid/starch productivity.
Published: 2019

26. An oomycete effector impairs autophagy in evolutionary distant organisms and favors host infection

Author: Gilles Peltier, Pascaline Auroy, Harald Keller, Franck Panabières, Kuhn M, Sophie Pagnotta, Fantao Kong, Allasia, Julie Cazareth, Testi S, Institut Sophia Agrobiotech (ISA), Institut National de la Recherche Agronomique (INRA)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Centre Commun de Microscopie Appliquée [Nice] (CCMA), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA), Institut de pharmacologie moléculaire et cellulaire (IPMC), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA)
Subjects: 0106 biological sciences, Oomycete, 0303 health sciences, Hyaloperonospora arabidopsidis, Programmed cell death, biology, Effector, ATG8, [SDV]Life Sciences [q-bio], Chlamydomonas, fungi, Chlamydomonas reinhardtii, biology.organism_classification, 01 natural sciences, Cell biology, 03 medical and health sciences, Arabidopsis, 030304 developmental biology, 010606 plant biology & botany
Abstract: An arsenal of effector proteins from plant pathogenic Phytophthora species manipulates their host from inside the cells. Phytophthora parasitica produces the effector AVH195 during an initial, biotrophic phase of infection. The protein transiently impairs plant immune-associated hypersensitive cell death in Nicotiana. ATG8 Interaction Motifs in the protein indicate that the effector targets the autophagic core machinery. We selected a photosynthetic microalga with a single copy ATG8 gene as an alternative model to dissect AVH195-induced autophagic perturbation. AVH195 slows down autophagic flux in Chlamydomonas reinhardtii thus promoting the accumulation of cargo-rich vesicles. In yeast, membrane-associated AVH195 interacts with ATG8 from Chlamydomonas and with different ATG8 isoforms from Arabidopsis thaliana. The overexpression of Avh195 in Arabidopsis promotes growth of both infecting P. parasitica and Hyaloperonospora arabidopsidis, an obligate biotroph. To our knowledge, this report provides first evidence that an oomycete effector non-selectively targets ATG8 in different organisms from the green lineage to slow down autophagic flux for infection.
Published: 2019

27. The function of PROTOPORPHYRINOGEN IX OXIDASE in chlorophyll biosynthesis requires oxidised plastoquinone in Chlamydomonas reinhardtii

Author: Pawel Brzezowski, Michel Havaux, Gilles Peltier, Brigitte Ksas, Jean Alric, Xenie Johnson, Marie Chazaux, Bernhard Grimm, Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Signalisation de l'Adaptation des Végétaux à l'Environnement (SAVE), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Humboldt-Universität zu Berlin, Photosynthèse & Environnement (P&E), Bioénergie et Microalgues (EBM), ANR-14-CE05-0041,ChloroPaths,Production in vivo et in silico de mutants affectant les voies de la photosynthèse(2014), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Plant Environmental Physiology and Stress Signaling (PEPSS), Humboldt University Of Berlin, and Environnement, Bioénergie, Microalgues et Plantes (EBMP)
Subjects: 0106 biological sciences, [SDV]Life Sciences [q-bio], Medicine (miscellaneous), Chlamydomonas reinhardtii, Plastoquinone, 01 natural sciences, Plastid terminal oxidase, General Biochemistry, Genetics and Molecular Biology, 03 medical and health sciences, chemistry.chemical_compound, lcsh:QH301-705.5, 030304 developmental biology, 0303 health sciences, Protoporphyrin IX, biology, Cytochrome b6f complex, DCMU, biology.organism_classification, 3. Good health, Protoporphyrinogen IX, lcsh:Biology (General), chemistry, Biochemistry, Chlorophyll, General Agricultural and Biological Sciences, 010606 plant biology & botany
Abstract: In the last common enzymatic step of tetrapyrrole biosynthesis, prior to the branching point leading to the biosynthesis of heme and chlorophyll, protoporphyrinogen IX (Protogen) is oxidised to protoporphyrin IX (Proto) by protoporphyrinogen IX oxidase (PPX). The absence of thylakoid-localised plastid terminal oxidase 2 (PTOX2) and cytochrome b6f complex in the ptox2 petB mutant, results in almost complete reduction of the plastoquinone pool (PQ pool) in light. Here we show that the lack of oxidised PQ impairs PPX function, leading to accumulation and subsequently uncontrolled oxidation of Protogen to non-metabolised Proto. Addition of 3(3,4-Dichlorophenyl)-1,1-dimethylurea (DCMU) prevents the over-reduction of the PQ pool in ptox2 petB and decreases Proto accumulation. This observation strongly indicates the need of oxidised PQ as the electron acceptor for the PPX reaction in Chlamydomonas reinhardtii. The PPX-PQ pool interaction is proposed to function as a feedback loop between photosynthetic electron transport and chlorophyll biosynthesis. Pawel Brzezowski et al. demonstrated existence of a link between chlorophyll biosynthesis and photosynthetic electron transport in Chlamydomonas reinhardtii. The lack of oxidised plastoquinone pool impairs function of PROTOPORPHYRINOGEN IX OXIDASE, leading to accumulation of non-metabolised protoporphyrin IX.
Published: 2019

28. Branched-Chain Amino Acid Catabolism Impacts Triacylglycerol Homeostasis in Chlamydomonas reinhardtii

Author: Yariv Brotman, Ismael Torres-Romero, Yonghua Li-Beisson, Stéphan Cuiné, Gilles Peltier, Bertrand Legeret, Emmanuelle Billon, Fantao Kong, Fred Beisson, Adrien Burlacot, Yuanxue Liang, Alisdair R. Fernie, Saleh Alseekh, Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Dalian University of Technology, Bioénergie et Microalgues (EBM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Max Planck Institute of Molecular Plant Physiology (MPI-MP), Max-Planck-Gesellschaft, ANR-11-IDEX-0001,Amidex,INITIATIVE D'EXCELLENCE AIX MARSEILLE UNIVERSITE(2011), European Project: 664621,H2020,H2020-WIDESPREAD-2014-1,PlantaSYST(2015), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Environnement, Bioénergie, Microalgues et Plantes (EBMP)
Subjects: 0106 biological sciences, 2. Zero hunger, chemistry.chemical_classification, biology, Physiology, Catabolism, Chemistry, Mutant, Chlamydomonas, Branched-chain amino acid, Chlamydomonas reinhardtii, Plant Science, Metabolism, [SDV.BC]Life Sciences [q-bio]/Cellular Biology, biology.organism_classification, 01 natural sciences, Amino acid, chemistry.chemical_compound, Biosynthesis, Biochemistry, Genetics, [SDV.BV]Life Sciences [q-bio]/Vegetal Biology, ComputingMilieux_MISCELLANEOUS, 010606 plant biology & botany
Abstract: Nitrogen (N) starvation-induced triacylglycerol (TAG) synthesis, and its complex relationship with starch metabolism in algal cells, has been intensively studied; however, few studies have examined the interaction between amino acid metabolism and TAG biosynthesis. Here, via a forward genetic screen for TAG homeostasis, we isolated a Chlamydomonas (Chlamydomonas reinhardtii) mutant (bkdE1α) that is deficient in the E1α subunit of the branched-chain ketoacid dehydrogenase (BCKDH) complex. Metabolomics analysis revealed a defect in the catabolism of branched-chain amino acids in bkdE1α Furthermore, this mutant accumulated 30% less TAG than the parental strain during N starvation and was compromised in TAG remobilization upon N resupply. Intriguingly, the rate of mitochondrial respiration was 20% to 35% lower in bkdE1α compared with the parental strains. Three additional knockout mutants of the other components of the BCKDH complex exhibited phenotypes similar to that of bkdE1α Transcriptional responses of BCKDH to different N status were consistent with its role in TAG homeostasis. Collectively, these results indicate that branched-chain amino acid catabolism contributes to TAG metabolism by providing carbon precursors and ATP, thus highlighting the complex interplay between distinct subcellular metabolisms for oil storage in green microalgae.
Published: 2019

29. Subcellular Energetics and Carbon Storage in Chlamydomonas

Author: Gilles Peltier, Adrien Burlacot, Yonghua Li-Beisson, Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Bioénergie et Microalgues (EBM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Environnement, Bioénergie, Microalgues et Plantes (EBMP)
Subjects: 0106 biological sciences, 0301 basic medicine, organelle, Biomass, Photosynthesis, oil, 01 natural sciences, 7. Clean energy, 03 medical and health sciences, chemistry.chemical_compound, chloroplast, peroxisome, lcsh:QH301-705.5, Fatty acid synthesis, Cellular compartment, photosynthesis, biology, starch, Chlamydomonas, food and beverages, General Medicine, Metabolism, reductant, Peroxisome, biology.organism_classification, Chloroplast, mitochondria, phosphorylating power, [SDV.BV.AP]Life Sciences [q-bio]/Vegetal Biology/Plant breeding, 030104 developmental biology, chemistry, Biochemistry, lcsh:Biology (General), 13. Climate action, metabolic shuttles, 010606 plant biology & botany
Abstract: International audience; Microalgae have emerged as a promising platform for production of carbon-and energy-rich molecules, notably starch and oil. Establishing an economically viable algal biotechnology sector requires a holistic understanding of algal photosynthesis, physiology, cell cycle and metabolism. Starch/oil productivity is a combined effect of their cellular content and cell division activities. Cell growth, starch and fatty acid synthesis all require carbon building blocks and a source of energy in the form of ATP and NADPH, but with a different requirement in ATP/NADPH ratio. Thus, several cellular mechanisms have been developed by microalgae to balance ATP and NADPH supply which are essentially produced by photosynthesis. Major energy management mechanisms include ATP production by the chloroplast-based cyclic electron flow and NADPH removal by water-water cycles. Furthermore, energetic coupling between chloroplast and other cellular compartments, mitochondria and peroxisome, is increasingly recognized as an important process involved in the chloroplast redox poise. Emerging literature suggests that alterations of energy management pathways affect not only cell fitness and survival, but also influence biomass content and composition. These emerging discoveries are important steps towards diverting algal photosynthetic energy to useful products for biotechnological applications.
Published: 2019

30. Saturating Light Induces Sustained Accumulation of Oil in Plastidal Lipid Droplets in Chlamydomonas reinhardtii

Author: Yuanxue Liang, Sabine Brugière, Gilles Peltier, Bertrand Legeret, Marianne Tardif, Yonghua Li-Beisson, Brian Jones, Pascaline Auroy, Fred Beisson, Stéphan Cuiné, Hugh D. Goold, Hélène Javot, Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Bioénergie et Microalgues (EBM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Laboratoire de Biologie à Grande Échelle (BGE - UMR S1038), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Signalisation de l'Adaptation des Végétaux à l'Environnement (SAVE), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Environnement, Bioénergie, Microalgues et Plantes (EBMP), Plant Environmental Physiology and Stress Signaling (PEPSS), Synthèse et étude de systèmes à intêret biologique (SEESIB), and Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)
Subjects: 2. Zero hunger, 0301 basic medicine, biology, Physiology, [SDV]Life Sciences [q-bio], Endoplasmic reticulum, Photobioreactor, Chlamydomonas reinhardtii, Biomass, Lipid metabolism, Plant Science, biology.organism_classification, Photosynthesis, 7. Clean energy, Polar membrane, 03 medical and health sciences, 030104 developmental biology, Biochemistry, Lipid droplet, Genetics, Biophysics, ComputingMilieux_MISCELLANEOUS
Abstract: Enriching algal biomass in energy density is an important goal in algal biotechnology. Nitrogen (N) starvation is considered the most potent trigger of oil accumulation in microalgae and has been thoroughly investigated. However, N starvation causes the slow down and eventually the arrest of biomass growth. In this study, we show that exposing a Chlamydomonas reinhardtii culture to saturating light (SL) under a nonlimiting CO2 concentration in turbidostatic photobioreactors induces a sustained accumulation of lipid droplets (LDs) without compromising growth, which results in much higher oil productivity than N starvation. We also show that the polar membrane lipid fraction of SL-induced LDs is rich in plastidial lipids (approximately 70%), in contrast to N starvation-induced LDs, which contain approximately 60% lipids of endoplasmic reticulum origin. Proteomic analysis of LDs isolated from SL-exposed cells identified more than 200 proteins, including known proteins of lipid metabolism, as well as 74 proteins uniquely present in SL-induced LDs. LDs induced by SL and N depletion thus differ in protein and lipid contents. Taken together, lipidomic and proteomic data thus show that a large part of the sustained oil accumulation occurring under SL is likely due to the formation of plastidial LDs. We discuss our data in relation to the different metabolic routes used by microalgae to accumulate oil reserves depending on cultivation conditions. Finally, we propose a model in which oil accumulation is governed by an imbalance between photosynthesis and growth, which can be achieved by impairing growth or by boosting photosynthetic carbon fixation, with the latter resulting in higher oil productivity.
Published: 2016

31. NDH-1 and NDH-2 Plastoquinone Reductases in Oxygenic Photosynthesis

Author: Gilles Peltier, Toshiharu Shikanai, Eva-Mari Aro, Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Bioénergie et Microalgues (EBM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Molecular Plant Biology, University of Turku, University of Turku, Department of Botany, Kyoto University, Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Environnement, Bioénergie, Microalgues et Plantes (EBMP)
Subjects: 0106 biological sciences, 0301 basic medicine, Chloroplasts, Photosystem II, Physiology, [SDV]Life Sciences [q-bio], Cell Respiration, Plastoquinone, Plant Science, Biology, Cyanobacteria, Photosynthesis, Photosystem I, 01 natural sciences, 7. Clean energy, Electron Transport, 03 medical and health sciences, chemistry.chemical_compound, Quinone Reductases, Molecular Biology, ComputingMilieux_MISCELLANEOUS, Photosystem, Photosystem I Protein Complex, Cytochrome b6f complex, Photosystem II Protein Complex, NADH Dehydrogenase, Evolution of photosynthesis, Cell Biology, Chlororespiration, Plants, Adaptation, Physiological, Oxygen, 030104 developmental biology, Biochemistry, chemistry, Ferredoxins, 010606 plant biology & botany
Abstract: Oxygenic photosynthesis converts solar energy into chemical energy in the chloroplasts of plants and microalgae as well as in prokaryotic cyanobacteria using a complex machinery composed of two photosystems and both membrane-bound and soluble electron carriers. In addition to the major photosynthetic complexes photosystem II (PSII), cytochrome b6f, and photosystem I (PSI), chloroplasts also contain minor components, including a well-conserved type I NADH dehydrogenase (NDH-1) complex that functions in close relationship with photosynthesis and likewise originated from the endosymbiotic cyanobacterial ancestor. Some plants and many microalgal species have lost plastidial ndh genes and a functional NDH-1 complex during evolution, and studies have suggested that a plastidial type II NADH dehydrogenase (NDH-2) complex substitutes for the electron transport activity of NDH-1. However, although NDH-1 was initially thought to use NAD(P)H as an electron donor, recent research has demonstrated that both chloroplast and cyanobacterial NDH-1s oxidize reduced ferredoxin. We discuss more recent findings related to the biochemical composition and activity of NDH-1 and NDH-2 in relation to the physiology and regulation of photosynthesis, particularly focusing on their roles in cyclic electron flow around PSI, chlororespiration, and acclimation to changing environments.
Published: 2016

32. Lipidomic and transcriptomic analyses of Chlamydomonas reinhardtii under heat stress unveil a direct route for the conversion of membrane lipids into storage lipids

Author: Fred Beisson, Yonghua Li-Beisson, Hoa Mai Nguyen, Bertrand Legeret, Gilles Peltier, Pascaline Auroy, Guillaume Blanc, and Miriam Schulz-Raffelt
Subjects: 0106 biological sciences, 0301 basic medicine, Phosphatidylethanolamine, chemistry.chemical_classification, Physiology, Membrane lipids, Fatty acid, Chlamydomonas reinhardtii, Lipid metabolism, Plant Science, Biology, Phospholipase, biology.organism_classification, 01 natural sciences, 03 medical and health sciences, chemistry.chemical_compound, 030104 developmental biology, Biochemistry, chemistry, Acyltransferase, Lipidomics, lipids (amino acids, peptides, and proteins), 010606 plant biology & botany
Abstract: Studying how photosynthetic cells modify membrane lipids in response to heat stress is important to understand how plants and microalgae adapt to daily fluctuations in temperature and to investigate new lipid pathways. Here, we investigate changes occurring in lipid molecular species and lipid metabolism genes during early response to heat stress in the model photosynthetic microorganism Chlamydomonas reinhardtii. Lipid molecular species analyses revealed that, after 60 min at 42 °C, a strong decrease in specific polyunsaturated membrane lipids was observed together with an increase in polyunsaturated triacylglycerols (TAGs) and diacylglycerols (DAGs). The fact that decrease in the major chloroplastic monogalactosyldiacylglycerol sn1-18:3/sn2-16:4 was mirrored by an accumulation of DAG sn1-18:3/sn2-16:4 and TAG sn1-18:3/sn2-16:4/sn3-18:3 indicated that newly accumulated TAGs were formed via direct conversion of monogalactosyldiacylglycerols to DAGs then TAGs. Lipidomic analyses showed that the third fatty acid of a TAG likely originated from a phosphatidylethanolamine or a diacylglyceryl-O-4'-(N,N,N,-trimethyl)-homoserine betaine lipid species. Candidate genes for this TAG synthesis pathway were provided through comparative transcriptomic analysis and included a phospholipase A2 homolog and the DAG acyltransferase DGTT1. This study gives insights into the molecular events underlying changes in membrane lipids during heat stress and reveals an alternative route for TAG synthesis.
Published: 2016

33. PGRL1 and LHCSR3 Compensate for Each Other in Controlling Photosynthesis and Avoiding Photosystem I Photoinhibition during High Light Acclimation of Chlamydomonas Cells

Author: Gilles Peltier, Stéphan Cuiné, Frédéric Chaux, Isabelle Te, Pascaline Auroy, Xenie Johnson, Audrey Beyly-Adriano, Environnement, Bioénergie, Microalgues et Plantes (EBMP), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Biologie végétale et microbiologie environnementale - UMR7265 (BVME), Aix Marseille Université (AMU), ANR-14-CE05-0041,ChloroPaths,Production in vivo et in silico de mutants affectant les voies de la photosynthèse(2014), ANR-11-IDEX-0001,Amidex,INITIATIVE D'EXCELLENCE AIX MARSEILLE UNIVERSITE(2011), Bioénergie et Microalgues (EBM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, 0301 basic medicine, Photoinhibition, [SDV.BC.BC]Life Sciences [q-bio]/Cellular Biology/Subcellular Processes [q-bio.SC], Plant Science, Biology, Photosynthesis, Photosystem I, 01 natural sciences, Acclimatization, 03 medical and health sciences, Botany, Molecular Biology, ComputingMilieux_MISCELLANEOUS, Plant Proteins, Quenching (fluorescence), Photosystem I Protein Complex, Non-photochemical quenching, Chlamydomonas, Photosystem II Protein Complex, biology.organism_classification, 030104 developmental biology, Thylakoid, Biophysics, 010606 plant biology & botany
Abstract: In natural environments, photosynthetic organisms experience frequent changes in the light supply, requiring modulation of light harvesting and electron transfer reactions to avoid mismatch between light conversion and metabolic reactions that may result in the production of harmful reactive oxygen species. They have thus evolved photoprotective regulatory mechanisms including the dissipation of excess energy (or non-photochemical quenching, NPQ), which relies on specific light-harvesting antennae, such as PSBS and Light-Harvesting Complex Stress-Related 3 (LHCSR3) (Peers et al., 2009), and is triggered by low pH in the thylakoid lumen.
Published: 2017

34. The function of PROTOPORPHYRINOGEN IX OXIDASE in chlorophyll biosynthesis requires oxidised plastoquinone in

Author: Pawel, Brzezowski, Brigitte, Ksas, Michel, Havaux, Bernhard, Grimm, Marie, Chazaux, Gilles, Peltier, Xenie, Johnson, and Jean, Alric
Subjects: Chlorophyll, Feedback, Physiological, Cell biology, Herbicides, Plastoquinone, Molecular biology, Algal Proteins, Protoporphyrins, Article, Electron Transport, Cytochrome b6f Complex, Gene Expression Regulation, Plant, Diuron, Protoporphyrinogen Oxidase, Plastids, Photosynthesis, Oxidation-Reduction, Chlamydomonas reinhardtii, Plant Proteins
Abstract: In the last common enzymatic step of tetrapyrrole biosynthesis, prior to the branching point leading to the biosynthesis of heme and chlorophyll, protoporphyrinogen IX (Protogen) is oxidised to protoporphyrin IX (Proto) by protoporphyrinogen IX oxidase (PPX). The absence of thylakoid-localised plastid terminal oxidase 2 (PTOX2) and cytochrome b6f complex in the ptox2 petB mutant, results in almost complete reduction of the plastoquinone pool (PQ pool) in light. Here we show that the lack of oxidised PQ impairs PPX function, leading to accumulation and subsequently uncontrolled oxidation of Protogen to non-metabolised Proto. Addition of 3(3,4-Dichlorophenyl)-1,1-dimethylurea (DCMU) prevents the over-reduction of the PQ pool in ptox2 petB and decreases Proto accumulation. This observation strongly indicates the need of oxidised PQ as the electron acceptor for the PPX reaction in Chlamydomonas reinhardtii. The PPX-PQ pool interaction is proposed to function as a feedback loop between photosynthetic electron transport and chlorophyll biosynthesis., Pawel Brzezowski et al. demonstrated existence of a link between chlorophyll biosynthesis and photosynthetic electron transport in Chlamydomonas reinhardtii. The lack of oxidised plastoquinone pool impairs function of PROTOPORPHYRINOGEN IX OXIDASE, leading to accumulation of non-metabolised protoporphyrin IX.
Published: 2018

35. Structure-Function Analysis of Chloroplast Proteins via Random Mutagenesis Using Error-Prone PCR

Author: Gilles Peltier, Jean Alric, Pascaline Auroy, Francesca Zito, Louis Dumas, Xenie Johnson, Ecole Polytechnique Fédérale de Lausanne (EPFL), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Bioénergie et Microalgues (EBM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Physico-chimie moléculaire des membranes biologiques (PCMMB), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Environnement, Bioénergie, Microalgues et Plantes (EBMP), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), and Photosynthèse & Environnement (P&E)
Subjects: 0301 basic medicine, Physiology, [SDV]Life Sciences [q-bio], Mutant, Chlamydomonas reinhardtii, Plant Science, Gene Mutant, Polymerase Chain Reaction, 03 medical and health sciences, Chloroplast Proteins, Gene Knockout Techniques, Structure-Activity Relationship, Genetics, Gene, ComputingMilieux_MISCELLANEOUS, Gene Library, 030102 biochemistry & molecular biology, biology, Cytochrome b6f complex, Chemistry, Genetic Complementation Test, food and beverages, Breakthrough Technologies, Biolistics, Directed evolution, biology.organism_classification, 3. Good health, Chloroplast, Cytochrome b6f Complex, Biochemistry, Mutagenesis, Hydrophobic and Hydrophilic Interactions
Abstract: Site-directed mutagenesis of chloroplast genes was developed three decades ago and has greatly advanced the field of photosynthesis research. Here, we describe a new approach for generating random chloroplast gene mutants that combines error-prone polymerase chain reaction of a gene of interest with chloroplast complementation of the knockout Chlamydomonas reinhardtii mutant. As a proof of concept, we targeted a 300-bp sequence of the petD gene that encodes subunit IV of the thylakoid membrane-bound cytochrome b(6)f complex. By sequencing chloroplast transformants, we revealed 149 mutations in the 300-bp target petD sequence that resulted in 92 amino acid substitutions in the 100-residue target subunit IV sequence. Our results show that this method is suited to the study of highly hydrophobic, multisubunit, and chloroplast-encoded proteins containing cofactors such as hemes, iron-sulfur clusters, and chlorophyll pigments. Moreover, we show that mutant screening and sequencing can be used to study photosynthetic mechanisms or to probe the mutational robustness of chloroplast-encoded proteins, and we propose that this method is a valuable tool for the directed evolution of enzymes in the chloroplast.
Published: 2018

36. Interorganelle Communication: Peroxisomal MALATE DEHYDROGENASE 2 Connects Lipid Catabolism to Photosynthesis through Redox Coupling in Chlamydomonas

Author: Saleh Alseekh, Gilles Peltier, Alisdair R. Fernie, Bertrand Legeret, Fantao Kong, Anja Krieger-Liszkay, Fred Beisson, Adrien Burlacot, Yuanxue Liang, Yariv Brotman, Yonghua Li-Beisson, Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Bioénergie et Microalgues (EBM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Max Planck Institute of Molecular Plant Physiology (MPI-MP), Max-Planck-Gesellschaft, Système membranaires, photobiologie, stress et détoxication (SMPSD), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), ANR-13-JSV5-0005,MUsCA,Ingénierie métabolique d'une microalgue verte en vue de la production d'alcanes à chaine moyenne(2013), ANR-11-IDEX-0001,Amidex,INITIATIVE D'EXCELLENCE AIX MARSEILLE UNIVERSITE(2011), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Environnement, Bioénergie, Microalgues et Plantes (EBMP)
Subjects: 0106 biological sciences, 0301 basic medicine, Photosystem II, Chlamydomonas reinhardtii, Plant Science, Biology, Photosynthesis, 01 natural sciences, 03 medical and health sciences, Malate Dehydrogenase, [SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biochemistry [q-bio.BM], Research Articles, Chlamydomonas, Hydrogen Peroxide, Cell Biology, Metabolism, Carbon Dioxide, Peroxisome, biology.organism_classification, Electron transport chain, Chloroplast, [SDV.BV.AP]Life Sciences [q-bio]/Vegetal Biology/Plant breeding, 030104 developmental biology, Biochemistry, Mutation, Oxidation-Reduction, 010606 plant biology & botany
Abstract: International audience; Plants and algae must tightly coordinate photosynthetic electron transport and metabolic activities given that they often face fluctuating light and nutrient conditions. The exchange of metabolites and signaling molecules between organelles is thought to be central to this regulation but evidence for this is still fragmentary. Here we show that knocking out the peroxisome-located MALATE DEHYDROGENASE 2 (MDH2) of Chlamydomonas reinhardtii results in dramatic alterations not only in peroxisomal fatty acid breakdown but also in chloroplast starch metabolism and photosynthesis. mdh2 mutants accumulated 50% more storage lipid and twofold more starch than wild type during nitrogen deprivation. In parallel, mdh2 showed increased PSII yield and photosynthetic CO 2 fixation. Metabolite analyses revealed a >60% reduction in malate, together with increased levels of NADPH and H 2 O 2 in mdh2. Similar phenotypes were found upon high light exposure. Furthermore, based on the lack of starch accumulation in a knockout mutant of the H 2 O 2-producing peroxisomal ACYL-COA OXIDASE 2 and on the effects of H 2 O 2 supplementation, we propose that peroxisome-derived H 2 O 2 acts as a regulator of chloroplast metabolism. We conclude that peroxisomal MDH2 helps photoautotrophs cope with nitrogen scarcity and high light by transmitting the redox state of the peroxisome to the chloroplast by means of malate shuttle-and H 2 O 2-based redox signaling.
Published: 2018

37. Birth of a photosynthetic chassis: a MoClo toolkit enabling synthetic biology in the microalga chlamydomonas reinhardtii

Author: Julien Henri, Christophe H. Marchand, Lisa-Desiree Westrich, Justus Niemeyer, Aleix Gorchs Rovira, Francisco Navarro, Stéphane D. Lemaire, David C. Baulcombe, Thomas Baier, Susana Sauret-Gueto, Kevin Sarkissian, Felix Willmund, Wolfgang Hübner, Pascaline Auroy, María Esther Pérez-Pérez, Payam Mehrshahi, Mathieu Cassarini, Marcello De Mia, Félix de Carpentier, Antoine Danon, José L. Crespo, Kyle J. Lauersen, Jasmine Theis, Raphael Trösch, Gilles Peltier, Pierre Crozet, Poul Erik Jensen, Konstantinos Vavitsas, Alison G. Smith, Michael Schroda, Olaf Kruse, Benjamin Spaniol, Kamil Bakowski, Agence Nationale de la Recherche (France), German Research Foundation, Ministerio de Economía y Competitividad (España), Villum Fonden, Bielefeld University, Biotechnology and Biological Sciences Research Council (UK), Institut de biologie physico-chimique (IBPC (FR_550)), Centre National de la Recherche Scientifique (CNRS), University of Cambridge [UK] (CAM), Technische Universität Kaiserslautern (TU Kaiserslautern), University of Copenhagen = Københavns Universitet (KU), Universität Bielefeld = Bielefeld University, University of Sevilla, Bioénergie et Microalgues (EBM), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), University of Copenhagen = Københavns Universitet (UCPH), Universidad de Sevilla / University of Sevilla, Environnement, Bioénergie, Microalgues et Plantes (EBMP), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), ANR-17-CE05-0008,MIDWAY,Contrôle des Interfaces Electrochimiques pour de meilleurs electrocatalyseurs pour l'oxydation de l'eau(2017), Crozet, Pierre [0000-0001-5113-2407], Vavitsas, Konstantinos [0000-0002-6828-1000], Kruse, Olaf [0000-0001-9874-382X], Jensen, Poul-Erik [0000-0001-6524-7723], Smith, Alison G [0000-0001-6511-5704], and Apollo - University of Cambridge Repository
Subjects: 0301 basic medicine, Chassis, [SDV.BIO]Life Sciences [q-bio]/Biotechnology, Computer science, Golden Gate Cloning, Green Fluorescent Proteins, Biomedical Engineering, Chlamydomonas reinhardtii, Gene Expression, Computational biology, Biochemistry, Genetics and Molecular Biology (miscellaneous), Modularity, 03 medical and health sciences, Synthetic biology, Genes, Reporter, Algal biotechnology, Photosynthesis, Promoter Regions, Genetic, Cloning, biology, modular cloning, business.industry, Chlamydomonas, General Medicine, algal biotechnology, Modular design, [SDV.BV.BOT]Life Sciences [q-bio]/Vegetal Biology/Botanics, biology.organism_classification, Modular cloning, 030104 developmental biology, synthetic biology, business, Biotechnology, Plasmids
Abstract: Microalgae are regarded as promising organisms to develop innovative concepts based on their photosynthetic capacity that offers more sustainable production than heterotrophic hosts. However, to realize their potential as green cell factories, a major challenge is to make microalgae easier to engineer. A promising approach for rapid and predictable genetic manipulation is to use standardized synthetic biology tools and workflows. To this end we have developed a Modular Cloning toolkit for the green microalga Chlamydomonas reinhardtii. It is based on Golden Gate cloning with standard syntax, and comprises 119 openly distributed genetic parts, most of which have been functionally validated in several strains. It contains promoters, UTRs, terminators, tags, reporters, antibiotic resistance genes, and introns cloned in various positions to allow maximum modularity. The toolkit enables rapid building of engineered cells for both fundamental research and algal biotechnology. This work will make Chlamydomonas the next chassis for sustainable synthetic biology., This work was supported in part by Agence Nationale de la Recherche Grant ANR-17-CE05-0008 and LABEX DYNAMO ANR-LABX-011 (to P.C., A.D., F.d.C., J.H., C.H.M., M.d.M., K.S., M.C., and S.D.L.), by the DFG-funded TRR175 and FOR2092 (to F.W., B.S., J.N., J.T., L.W., R.T., and M.S.), by OpenPlant (BBSRC/EPSRC) (to F.J.N. and S.S.G.), by Ministerio de Economia y Competitividad Grants BFU2015-68216-P and BIO2015-74432-JIN (to J.L.C. and M.E.P.P.), by the VILLUM Foundation (Project no. 13363) (to P.E.J., K.B., K.V.), by the Technology Platforms at the Center for Biotechnology (CeBiTec) Bielefeld University (to K.L., T.B., and O.K.), by UK Biotechnology and Biological Sciences Research Council (BBSRC) (to P.M. and A.G.R.) and by ERA-SynBio project Sun2Chem (to P.A. and G.P.).
Published: 2018

38. Hunting the main player enabling Chlamydomonas reinhardtii growth under fluctuating light

Author: Martina, Jokel, Xenie, Johnson, Gilles, Peltier, Eva-Mari, Aro, and Yagut, Allahverdiyeva
Subjects: Light, Photosystem I Protein Complex, Gene Knockdown Techniques, Algal Proteins, Cell Respiration, Photosystem II Protein Complex, Photosynthesis, Genes, Plant, Chlamydomonas reinhardtii
Abstract: Photosynthetic organisms have evolved numerous photoprotective mechanisms and alternative electron sinks/pathways to fine-tune the photosynthetic apparatus under dynamic environmental conditions, such as varying carbon supply or fluctuations in light intensity. In cyanobacteria flavodiiron proteins (FDPs) protect the photosynthetic apparatus from photodamage under fluctuating light (FL). In Arabidopsis thaliana, which does not possess FDPs, the PGR5-related pathway enables FL photoprotection. The direct comparison of the pgr5, pgrl1 and flv knockout mutants of Chlamydomonas reinhardtii grown under ambient air demonstrates that all three proteins contribute to the survival of cells under FL, but to varying extents. The FDPs are crucial in providing a rapid electron sink, with flv mutant lines unable to survive even mild FL conditions. In contrast, the PGRL1 and PGR5-related pathways operate over relatively slower and longer time-scales. Whilst deletion of PGR5 inhibits growth under mild FL, the pgrl1 mutant line is only impacted under severe FL conditions. This suggests distinct roles, yet a close relationship, between the function of PGR5, PGRL1 and FDP proteins in photoprotection.
Published: 2017

39. Using coagulation–flocculation to harvest Chlamydomonas reinhardtii: Coagulant and flocculant efficiencies, and reuse of the liquid phase as growth medium

Author: Florian Delrue, Yohann Imbert, Jean-François Sassi, Gilles Peltier, and Gatien Fleury
Subjects: Growth medium, Flocculation, biology, Polyacrylamide, Cationic polymerization, Chlamydomonas reinhardtii, Biomass, biology.organism_classification, Pulp and paper industry, Chitosan, chemistry.chemical_compound, chemistry, Botany, Coagulation (water treatment), Agronomy and Crop Science
Abstract: article i nfo Coagulation-flocculation is an efficient, economic, and scalable process suitable for harvesting microalgae. The study tested the effectiveness of 11 agents (chitosan and 10 commercial, industrially available reference prod- ucts) forharvestingChlamydomonas reinhardtii,a modelmicroalga.The highest efficiencies(N95%)with the low- est dose (b30 g/kg of biomass for 2 of the 4 polymers tested) were achieved for highly charged cationic polyacrylamides with a high molecular weight. Mineral coagulants were less efficient. Efficiencies above 80% were attained for 2 out of 4 flocculants with doses ranging from 40 to 80 g/kg of dry biomass. Chitosan appeared tobea goodalternative to polyacrylamides; itattainedan efficiency of over90%fora 35g/kgdoseof drybiomass. The study further investigated a reuse of the supernatant resulting from the solid-liquid separation, an essential prerequisite to scale up the process. Two types of cultivation tests were performed for three selected—chitosan, polyaluminium chlorosulfate, and an 80% cationic polyacrylamide: 1) using various ratios of supernatant to fresh medium and 2) using various concentrations of flocculant in a fresh medium. These preliminary experiments showedthat flocculantresiduesalterthegrowth ofC. reinhardtii indifferent waysdepending onthe chemicalna- ture and concentration of the considered flocculant. No lethal toxicity was observed.
Published: 2015

40. The Chlamydomonas mex1 mutant shows impaired starch mobilization without maltose accumulation

Author: Christophe D'Hulst, Jean-Marie Lacroix, Gilles Peltier, Thierry Duchêne, Fabrice Wattebled, Yonghua Li-Beisson, Corentin Spriet, David Dauvillée, Nicolas Szydlowski, Miriam Schulz-Raffelt, Philippe Deschamps, Hande Tunçay, Justin Findinier, Unité de Glycobiologie Structurale et Fonctionnelle UMR 8576 (UGSF), Université de Lille-Centre National de la Recherche Scientifique (CNRS), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Environnement, Bioénergie, Microalgues et Plantes (EBMP), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Ecologie Systématique et Evolution (ESE), Université Paris-Sud - Paris 11 (UP11)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), Miniaturisation pour la Synthèse, l’Analyse et la Protéomique - UAR 3290 (MSAP), Unité de Glycobiologie Structurale et Fonctionnelle - UMR 8576 (UGSF), Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Bioénergie et Microalgues (EBM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Miniaturisation pour la Synthèse, l’Analyse et la Protéomique - USR 3290 (MSAP), Institut National de la Recherche Agronomique (INRA)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), and Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, 0301 basic medicine, Monosaccharide Transport Proteins, Physiology, Recombinant Fusion Proteins, [SDV]Life Sciences [q-bio], Mutant, Arabidopsis, Chlamydomonas reinhardtii, Gene Expression, Plant Science, 01 natural sciences, 03 medical and health sciences, chemistry.chemical_compound, Genes, Reporter, Escherichia coli, Plastids, Transgenes, Plastid envelope, Maltose, Phylogeny, ComputingMilieux_MISCELLANEOUS, biology, Chemistry, Chlamydomonas, Algal Proteins, food and beverages, Biological Transport, Starch, biology.organism_classification, Complementation, 030104 developmental biology, Biochemistry, Seedlings, Mutation, Heterologous expression, 010606 plant biology & botany
Abstract: The MEX1 locus of Chlamydomonas reinhardtii was identified in a genetic screen as a factor that affects starch metabolism. Mutation of MEX1 causes a slow-down in the mobilization of storage polysaccharide. Cosegregation and functional complementation analyses were used to assess the involvement of the Mex1 protein in starch degradation. Heterologous expression experiments performed in Escherichia coli and Arabidopsis thaliana allowed us to test the capacity of the algal protein in maltose export. In contrast to the A. thaliana mex1 mutant, the mutation in C. reinhardtii does not lead to maltose accumulation and growth impairment. Although localized in the plastid envelope, the algal protein does not transport maltose efficiently across the envelope, but partly complements the higher plant mutant. Both Mex orthologs restore the growth of the E. coli ptsG mutant strain on glucose-containing medium, revealing the capacity of these proteins to transport this hexose. These findings suggest that Mex1 is essential for starch mobilization in both Chlamydomonas and Arabidopsis, and that this protein family may support several functions and not only be restricted to maltose export across the plastidial envelope.
Published: 2017

41. A stromal region of cytochrome

Author: Louis, Dumas, Francesca, Zito, Stéphanie, Blangy, Pascaline, Auroy, Xenie, Johnson, Gilles, Peltier, and Jean, Alric
Subjects: Chlorophyll, Chloroplasts, Cytochrome b6f Complex, Photosystem I Protein Complex, Plastoquinone, Chlamydomonas, Light-Harvesting Protein Complexes, Photosystem II Protein Complex, Phosphorylation, Biological Sciences, Oxidation-Reduction, Protein Kinases
Abstract: Sunlight is a powerful but fluctuating energy source used by photosynthetic organisms as a substrate for biochemistry. To optimize photosynthetic efficiency, the distribution of energy input between the two photosystems is regulated through state transitions. This mechanism is common to all organisms of the green lineage and depends on the concerted response of the cytochrome b6f complex and the Stt7 kinase to changing redox conditions along the electron transport chain. The identification of a cytochrome b6f stromal motif involved in state transitions gives insight into the mechanism of Stt7 kinase activation.
Published: 2017

42. 8. Les promesses des micro-algues pour la production de biodiesel

Author: Gilles Peltier and Antoine Sciandra
Published: 2017

43. An algal photoenzyme converts fatty acids to hydrocarbons

Author: Bertrand Légeret, Pavel Müller, Yonghua Li-Beisson, Yohann Couté, David Pignol, Fred Beisson, Gilles Peltier, Damien Sorigué, Emmanuelle Billon, Stéphanie Blangy, Didier Nurizzo, Pascal Arnoux, Pierre Richaud, Solène L. Y. Moulin, Klaus Brettel, Stéphan Cuiné, Sabine Brugière, Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Synthèse et étude de systèmes à intêret biologique (SEESIB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS), Troubles cognitifs dégénératifs et vasculaires (DN2M), Université de Lille-Centre Hospitalier Régional Universitaire [Lille] (CHRU Lille)-INSERM, Bioénergie et Microalgues (EBM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Etude de la dynamique des protéomes (EDyP), Laboratoire de Biologie à Grande Échelle (BGE - UMR S1038), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Grenoble Alpes (UGA)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Grenoble Alpes (UGA), European Synchrotron Radiation Facility (ESRF), Institut de Biologie Intégrative de la Cellule (I2BC), Université Paris-Sud - Paris 11 (UP11)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay, Microbiologie Environnementale et Moléculaire (MEM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Etude de la dynamique des protéomes (EDyP ), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), ANR-13-JSV5-0005,MUsCA,Ingénierie métabolique d'une microalgue verte en vue de la production d'alcanes à chaine moyenne(2013), ANR-11-IDEX-0001,Amidex,INITIATIVE D'EXCELLENCE AIX MARSEILLE UNIVERSITE(2011), ANR-10-INBS-0005,FRISBI,Infrastructure Française pour la Biologie Structurale Intégrée(2010), ANR-10-INBS-0008,ProFI,Infrastructure Française de Protéomique(2010), Biologie végétale et microbiologie environnementale - UMR7265 ( BVME ), Centre National de la Recherche Scientifique ( CNRS ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Aix Marseille Université ( AMU ), Laboratoire de Biologie à Grande Échelle ( BGE - UMR S1038 ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Grenoble Alpes [Saint Martin d'Hères]-Institut National de la Santé et de la Recherche Médicale ( INSERM ), European Synchrotron Radiation Facility ( ESRF ), Biologie et Biotechnologie des Cyanobactéries ( B2CYA ), Département Microbiologie ( Dpt Microbio ), Institut de Biologie Intégrative de la Cellule ( I2BC ), Université Paris-Sud - Paris 11 ( UP11 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ) -Université Paris-Sud - Paris 11 ( UP11 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ) -Institut de Biologie Intégrative de la Cellule ( I2BC ), Université Paris-Sud - Paris 11 ( UP11 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ) -Université Paris-Sud - Paris 11 ( UP11 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ), Université Paris-Sud - Paris 11 ( UP11 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ), and Environnement, Bioénergie, Microalgues et Plantes (EBMP)
Subjects: 0301 basic medicine, Photosynthetic reaction centre, Light, Carboxy-Lyases, Decarboxylation, [SDV]Life Sciences [q-bio], Chlorella, [SDV.BC]Life Sciences [q-bio]/Cellular Biology, Alkenes, 010402 general chemistry, 01 natural sciences, Cofactor, 03 medical and health sciences, chemistry.chemical_compound, Oxidoreductase, Alkanes, Phylogeny, ComputingMilieux_MISCELLANEOUS, Plant Proteins, chemistry.chemical_classification, Flavin adenine dinucleotide, Multidisciplinary, biology, [ SDV.BC ] Life Sciences [q-bio]/Cellular Biology, Fatty Acids, Fatty acid, Lipid metabolism, Lipid Metabolism, Photochemical Processes, 0104 chemical sciences, 030104 developmental biology, Enzyme, chemistry, Biochemistry, Biocatalysis, Flavin-Adenine Dinucleotide, biology.protein, Oxidoreductases
Abstract: Algal enzyme driven by blue light Microalgae make hydrocarbons. In searching for the enzyme responsible, Sorigué et al. found a glucose-methanolcholine oxidoreductase (see the Perspective by Scrutton). Expression of the enzyme in Escherichia coli showed that hydrocarbon production requires visible light. In fact, the enzyme requires a constant input of blue photons to carry out its catalytic reaction. A long hydrophobic tunnel in the enzyme stabilizes the fatty acid substrates in proximity to the flavin adenine dinucleotide cofactor. Science , this issue p. 903 ; see also p. 872
Published: 2017

44. Chlamydomonas carries out fatty acid β-oxidation in ancestral peroxisomes using a bona fide acyl-CoA oxidase

Author: Bertrand Legeret, Audrey Beyly-Adriano, Johnathan A. Napier, Yuanxue Liang, Gilles Peltier, Stéphanie Blangy, Fantao Kong, Fred Beisson, Yonghua Li-Beisson, Richard P. Haslam, Environnement, Bioénergie, Microalgues et Plantes (EBMP), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Biological Chemistry and Crop Protection, Rothamsted Research, Biotechnology and Biological Sciences Research Council (BBSRC)-Biotechnology and Biological Sciences Research Council (BBSRC), ANR-13-JSV5-0005,MUsCA,Ingénierie métabolique d'une microalgue verte en vue de la production d'alcanes à chaine moyenne(2013), ANR-11-IDEX-0001,Amidex,INITIATIVE D'EXCELLENCE AIX MARSEILLE UNIVERSITE(2011), Bioénergie et Microalgues (EBM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, 0301 basic medicine, Nitrogen, Mutant, Chlamydomonas reinhardtii, lipid droplet, hydrogen peroxide, Plant Science, 01 natural sciences, 03 medical and health sciences, Peroxisomes, Genetics, microbodies, Acyl-CoA oxidase, Microbody, nitrogen starvation, [SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biochemistry [q-bio.BM], chemistry.chemical_classification, Oxidase test, biology, Chlamydomonas, catalase, acyl-CoA oxidase, Fatty acid, lipid catabolism, Cell Biology, Peroxisome, Lipid Metabolism, biology.organism_classification, lipid homeostasis, 030104 developmental biology, Biochemistry, chemistry, oil content, Oxidation-Reduction, 010606 plant biology & botany
Abstract: International audience; Peroxisomes are thought to have played a key role in the evolution of metabolic networks of photosynthetic organisms by connecting oxidative and biosynthetic routes operating in different compartments. While the various oxidative pathways operating in the peroxisomes of higher plants are fairly well characterized, the reactions present in the primitive peroxisomes (microbodies) of algae are poorly understood. Screening of a Chlamydomonas insertional mutant library identified a strain strongly impaired in oil remobilization and defective in Cre05.g232002(CrACX2), a gene encoding a member of the acyl-CoA oxidase/dehydrogenase superfamily. The purified recombinant CrACX2 expressed in Escherichia coli catalyzed the oxidation of fatty acyl-CoAs into trans-2-enoyl-CoA and produced H 2 O 2. This result demonstrated that CrACX2 is a genuine acyl-CoA oxidase, which is responsible for the first step of the peroxisomal fatty acid (FA) β-oxidation spiral. A fluorescent protein-tagging study pointed to a peroxisomal location of CrACX2. The importance of peroxisomal FA β-oxidation in algal physiology was shown by the impact of the mutation on FA turnover during day/night cycles. Moreover, under nitrogen depletion the mutant accumulated 20% more oil than the wild type, illustrating the potential of β-oxidation mutants for algal biotechnology. This study provides experimental evidence that a plant-type FA β-oxidation involving H 2 O 2-producing acyl-CoA oxidation activity has already evolved in the microbodies of the unicellular green alga Chlamydomonas reinhardtii.
Published: 2017

45. A stromal region of cytochrome $b_6f$ subunit IV is involved in the activation of the Stt7 kinase in Chlamydomonas

Author: Francesca Zito, Stéphanie Blangy, Xenie Johnson, Gilles Peltier, Jean Alric, Pascaline Auroy, Louis Dumas, Biologie végétale et microbiologie environnementale - UMR7265 (BVME), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de biologie physico-chimique des protéines membranaires (LBPC-PM (UMR_7099)), Institut de biologie physico-chimique (IBPC (FR_550)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Environnement, Bioénergie, Microalgues et Plantes (EBMP), Photosynthèse & Environnement (P&E), ANR-11-LABX-0011,DYNAMO,Dynamique des membranes transductrices d'énergie : biogénèse et organisation supramoléculaire.(2011), ANR-14-CE05-0041,ChloroPaths,Production in vivo et in silico de mutants affectant les voies de la photosynthèse(2014), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Bioénergie et Microalgues (EBM), Institut de biologie physico-chimique (IBPC), and ANR-11-LABX-0011/11-LABX-0011,DYNAMO,Dynamique des membranes transductrices d'énergie : biogénèse et organisation supramoléculaire.(2011)
Subjects: 0106 biological sciences, 0301 basic medicine, Cytochrome, Protein subunit, Plastoquinone, 01 natural sciences, environment and public health, 03 medical and health sciences, chemistry.chemical_compound, [SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biochemistry [q-bio.BM], Photosystem, Multidisciplinary, biology, Cytochrome b6f complex, Autophosphorylation, Chlamydomonas, [SDV.BV.BOT]Life Sciences [q-bio]/Vegetal Biology/Botanics, biology.organism_classification, Cell biology, [SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biomolecules [q-bio.BM], enzymes and coenzymes (carbohydrates), 030104 developmental biology, chemistry, Protein kinase domain, Biochemistry, embryonic structures, biology.protein, cardiovascular system, 010606 plant biology & botany
Abstract: International audience; The cytochrome (cyt) $b_6f$ complex and Stt7 kinase regulate the antenna sizes of photosystems I and II through state transitions, which are mediated by a reversible phosphorylation of light harvesting complexes II, depending on the redox state of the plastoquinone pool. When the pool is reduced, the cyt $b_6f$ activates the Stt7 kinase through a mechanism that is still poorly understood. After random mutagenesis of the chloroplast petD gene, coding for subunit IV of the cyt $b_6f$ complex, and complementation of a ΔpetDhost strain by chloroplast transformation, we screened for impaired state transitions in vivo by chlorophyll fluorescence imaging. We show that residues Asn122, Tyr124, and Arg125 in the stromal loop linking helices F and G of cyt $b_6f$ subunit IV are crucial for state transitions. In vitro reconstitution experiments with purified cyt $b_6f$ and recombinant Stt7 kinase domain show that cyt $b_6f$ enhances Stt7 autophosphorylation and that the Arg125 residue is directly involved in this process. The peripheral stromal structure of the cyt $b_6f$ complex had, until now, no reported function. Evidence is now provided of a direct interaction with Stt7 on the stromal side of the membrane
Published: 2017

46. Flavodiiron Proteins Promote Fast and Transient O 2 Photoreduction in Chlamydomonas

Author: Gilles Peltier, Pascaline Auroy, Stéphanie Blangy, Pierre Richaud, Frédéric Chaux, Malika Mekhalfi, Adrien Burlacot, Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Bioénergie et Microalgues (EBM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), ERA-SynBio project Sun2Chem, ANR-11-IDEX-0001,Amidex,INITIATIVE D'EXCELLENCE AIX MARSEILLE UNIVERSITE(2011), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Environnement, Bioénergie, Microalgues et Plantes (EBMP)
Subjects: 0106 biological sciences, 0301 basic medicine, Cyanobacteria, Physiology, chemistry.chemical_element, Chlamydomonas reinhardtii, Plant Science, Photosynthesis, 7. Clean energy, 01 natural sciences, Oxygen, 03 medical and health sciences, transient, Botany, Genetics, [SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biochemistry [q-bio.BM], Chlorophyll fluorescence, Quenching (fluorescence), photosynthesis, biology, Chlamydomonas, [SDV.BV.BOT]Life Sciences [q-bio]/Vegetal Biology/Botanics, biology.organism_classification, Electron transport chain, 030104 developmental biology, chemistry, 13. Climate action, uptake, Biophysics, fluorescence, production, MIMS, oxygen, Flavodiiron, 010606 plant biology & botany
Abstract: International audience; During oxygenic photosynthesis, the reducing power generated by light energy conversion is mainly used to reduce carbon dioxide. In bacteria and archae, flavodiiron (Flv) proteins catalyze O 2 or NO reduction, thus protecting cells against oxidative or nitrosative stress. These proteins are found in cyanobacteria, mosses, and microalgae, but have been lost in angiosperms. Here, we used chlorophyll fluorescence and oxygen exchange measurement using [ 18 O]-labeled O 2 and a membrane inlet mass spectrometer to characterize Chlamydomonas reinhardtii flvB insertion mutants devoid of both FlvB and FlvA proteins. We show that Flv proteins are involved in a photo-dependent electron flow to oxygen, which drives most of the photosynthetic electron flow during the induction of photosynthesis. As a consequence, the chlorophyll fluorescence patterns are strongly affected in flvB mutants during a light transient, showing a lower PSII operating yield and a slower nonphotochemical quenching induction. Photoautotrophic growth of flvB mutants was indistinguishable from the wild type under constant light, but severely impaired under fluctuating light due to PSI photo damage. Remarkably, net photosynthesis of flv mutants was higher than in the wild type during the initial hour of a fluctuating light regime, but this advantage vanished under long-term exposure, and turned into PSI photo damage, thus explaining the marked growth retardation observed in these conditions. We conclude that the C. reinhardtii Flv participates in a Mehler-like reduction of O 2 , which drives a large part of the photosynthetic electron flow during a light transient and is thus critical for growth under fluctuating light regimes.
Published: 2017

47. Improved oxygen tolerance of the Synechocystis sp. PCC 6803 bidirectional hydrogenase by site-directed mutagenesis of putative residues of the gas diffusion channel

Author: Gilles Peltier, Anne Volbeda, Pierre Richaud, Geneviève Guedeney, Melissa Cano, Emeline Aubert-Jousset, and Laurent Cournac
Subjects: Cyanobacteria, chemistry.chemical_classification, Hydrogenase, biology, Renewable Energy, Sustainability and the Environment, Chemistry, Synechocystis, Mutant, Mutagenesis, Energy Engineering and Power Technology, Condensed Matter Physics, biology.organism_classification, Enzyme assay, Fuel Technology, Enzyme, Biochemistry, biology.protein, Site-directed mutagenesis
Abstract: Although of potential biotechnological interest, photobiological H2 production from microalgae and cyanobacteria is strongly limited due to the oxygen sensitivity of hydrogenases, the H2-evolving enzymes. We study here the [NiFe] hydrogenase of the cyanobacterium Synechocystis sp. PCC 6803 to identify structural determinants of its sensitivity to O2. Based on previous work on the hydrogenase from Desulfovibrio fructosovorans and on a structural model of the Synechocystis hydrogenase, we have created various mutants of the Synechocystis enzyme. Amino acids residues homologous to those defining the end of the intramolecular gas channel in the D. fructosovorans enzyme were specifically targeted, these residues being previously described as critical for enzyme activity and tolerance to O2. We show here that mutation I64M of the Synechocystis enzyme alters gas diffusion kinetics and improves O2 tolerance. These results constitute the first report demonstrating that an O2 tolerance-related character could be transposed from a proteobacterial hydrogenase to a cyanobacterial one, and may constitute the first published improvement of O2 tolerance of a cyanobacterial enzyme by single site-directed mutagenesis.
Published: 2014

48. Hyper-accumulation of starch and oil in a Chlamydomonas mutant affected in a plant-specific DYRK kinase

Author: Pascaline Auroy, Vincent Chochois, Emmanuelle Billon, Yonghua Li-Beisson, David Dauvillée, Miriam Schulz-Raffelt, Stéphan Cuiné, Gilles Peltier, Environnement, Bioénergie, Microalgues et Plantes (EBMP), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Unité de Glycobiologie Structurale et Fonctionnelle UMR 8576 (UGSF), Université de Lille-Centre National de la Recherche Scientifique (CNRS), Support was also provided by the HélioBiotec platform (funded by the European Regional Development Fund, the Région Provence Alpes Côte d’Azur, the French Ministry of Research, and the 'Commissariat à l’Energie Atomique et aux Energies Alternatives')., ANR-08-BIOE-0002,ALGOMICS,ETUDES GLOBALES DE LA CONVERSION ET DU STOCKAGE DE L'ENERGIE CHEZ LES MICROALGUES(2008), ANR-10-BIOE-0004,Algo-H2,Optimisations génétiques, métaboliques, et procédé de la photobioproduction d'hydrogène par la microalgue verte Chlamydomonas reinhardtii(2010), ANR-11-IDEX-0001,Amidex,INITIATIVE D'EXCELLENCE AIX MARSEILLE UNIVERSITE(2011), CNRS, Université de Lille, Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) [BIAM], Unité de Glycobiologie Structurale et Fonctionnelle UMR 8576 [UGSF], Bioénergie et Microalgues (EBM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Institut National de la Recherche Agronomique (INRA)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Unité de Glycobiologie Structurale et Fonctionnelle - UMR 8576 (UGSF), Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), ANR: ALGOH2,Optimisations génétiques, métaboliques, et procédé de photobioproduction d’hydrogène par la microalgue verte Chlamydomonas reinhardtii, and ANR-11-IDEX-0001-02/11-IDEX-0001,AMIDEX,AMIDEX(2011)
Subjects: 0301 basic medicine, Kinase, Nutrient deprivation, Oil, Starch, Microalgae, Photosynthesis, Chlamydomonas, DYRK, [SDV]Life Sciences [q-bio], Mutant, Chlamydomonas reinhardtii, Management, Monitoring, Policy and Law, 7. Clean energy, Applied Microbiology and Biotechnology, 03 medical and health sciences, chemistry.chemical_compound, Nutrient, Botany, 2. Zero hunger, biology, Renewable Energy, Sustainability and the Environment, Research, biology.organism_classification, Cell biology, 030104 developmental biology, General Energy, chemistry, Biofuel, Biotechnology
Abstract: Background Because of their high biomass productivity and their ability to accumulate high levels of energy-rich reserve compounds such as oils or starch, microalgae represent a promising feedstock for the production of biofuel. Accumulation of reserve compounds takes place when microalgae face adverse situations such as nutrient shortage, conditions which also provoke a stop in cell division, and down-regulation of photosynthesis. Despite growing interest in microalgal biofuels, little is known about molecular mechanisms controlling carbon reserve formation. In order to discover new regulatory mechanisms, and identify genes of interest to boost the potential of microalgae for biofuel production, we developed a forward genetic approach in the model microalga Chlamydomonas reinhardtii. Results By screening an insertional mutant library on the ability of mutants to accumulate and re-mobilize reserve compounds, we isolated a Chlamydomonas mutant (starch degradation 1, std1) deficient for a dual-specificity tyrosine-phosphorylation-regulated kinase (DYRK). The std1 mutant accumulates higher levels of starch and oil than wild-type and maintains a higher photosynthetic activity under nitrogen starvation. Phylogenetic analysis revealed that this kinase (named DYRKP) belongs to a plant-specific subgroup of the evolutionarily conserved DYRK kinase family. Furthermore, hyper-accumulation of storage compounds occurs in std1 mostly under low light in photoautotrophic condition, suggesting that the kinase normally acts under conditions of low energy status to limit reserve accumulation. Conclusions The DYRKP kinase is proposed to act as a negative regulator of the sink capacity of photosynthetic cells that integrates nutrient and energy signals. Inactivation of the kinase strongly boosts accumulation of reserve compounds under photoautotrophic nitrogen deprivation and allows maintaining high photosynthetic activity. The DYRKP kinase therefore represents an attractive target for improving the energy density of microalgae or crop plants. Electronic supplementary material The online version of this article (doi:10.1186/s13068-016-0469-2) contains supplementary material, which is available to authorized users.
Published: 2016

49. Cytochrome b 6 f function and localization, phosphorylation state of thylakoid membrane proteins and consequences on cyclic electron flow

Author: Gilles Peltier, Marie Chazaux, Louis Dumas, Jean Alric, Xenie Johnson, Ecole Polytechnique Fédérale de Lausanne (EPFL), Biologie végétale et microbiologie environnementale - UMR7265 (BVME), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Bioénergie et Microalgues (EBM), ANR-14-CE05-0041,ChloroPaths,Production in vivo et in silico de mutants affectant les voies de la photosynthèse(2014), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Environnement, Bioénergie, Microalgues et Plantes (EBMP), and Photosynthèse & Environnement (P&E)
Subjects: 0106 biological sciences, 0301 basic medicine, Photosynthetic reaction centre, Light, Photosystem II, Plastoquinone, [SDV]Life Sciences [q-bio], Electrons, macromolecular substances, Plant Science, Biology, Photochemistry, Thylakoids, 01 natural sciences, Biochemistry, Electron Transport, Chloroplast Proteins, 03 medical and health sciences, chemistry.chemical_compound, Chlorophyta, Light-dependent reactions, Phosphorylation, Photosynthesis, ComputingMilieux_MISCELLANEOUS, Photosystem, Photosystem I Protein Complex, Cytochrome b6f complex, Photosystem II Protein Complex, food and beverages, Cell Biology, General Medicine, Cytochromes b, 030104 developmental biology, chemistry, Thylakoid, Quantasome, Biophysics, Oxidation-Reduction, 010606 plant biology & botany
Abstract: Both the structure and the protein composition of thylakoid membranes have an impact on light harvesting and electron transfer in the photosynthetic chain. Thylakoid membranes form stacks and lamellae where photosystem II and photosystem I localize, respectively. Light-harvesting complexes II can be associated to either PSII or PSI depending on the redox state of the plastoquinone pool, and their distribution is governed by state transitions. Upon state transitions, the thylakoid ultrastructure and lateral distribution of proteins along the membrane are subject to significant rearrangements. In addition, quinone diffusion is limited to membrane microdomains and the cytochrome b 6 f complex localizes either to PSII-containing grana stacks or PSI-containing stroma lamellae. Here, we discuss possible similarities or differences between green algae and C3 plants on the functional consequences of such heterogeneities in the photosynthetic electron transport chain and propose a model in which quinones, accepting electrons either from PSII (linear flow) or NDH/PGR pathways (cyclic flow), represent a crucial control point. Our aim is to give an integrated description of these processes and discuss their potential roles in the balance between linear and cyclic electron flows.
Published: 2016

50. Chlamydomonas reinhardtii PsbS protein is functional and accumulates rapidly and transiently under high light

Author: Stefano Caffarri, Pascaline Auroy, Tania Tibiletti, Gilles Peltier, Luminy Génétique et Biophysique des Plantes (LGBP), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Bioénergie et Microalgues (EBM), ANR-11-IDEX-0001,Amidex,INITIATIVE D'EXCELLENCE AIX MARSEILLE UNIVERSITE(2011), ANR-12-JSV8-0001,PHOTO-plast,Structure et plasticité des photosystèmes en réponse à l'environnement chez les plantes et les algues, une clé pour comprendre et améliorer la croissance.(2012), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Environnement, Bioénergie, Microalgues et Plantes (EBMP)
Subjects: 0106 biological sciences, 0301 basic medicine, biology, Physiology, [SDV]Life Sciences [q-bio], Chlamydomonas, Chlamydomonas reinhardtii, Plant Science, biology.organism_classification, Photosynthesis, 01 natural sciences, Electron transport chain, 03 medical and health sciences, 030104 developmental biology, Photoprotection, Arabidopsis, Botany, Genetics, Biophysics, Plastid, ComputingMilieux_MISCELLANEOUS, 010606 plant biology & botany, Transplastomic plant
Abstract: Photosynthetic organisms must respond to excess light in order to avoid photo-oxidative stress. In plants and green algae the fastest response to high light is non-photochemical quenching (NPQ), a process that allows the safe dissipation of the excess energy as heat. This phenomenon is triggered by the low luminal pH generated by photosynthetic electron transport. In vascular plants the main sensor of the low pH is the PsbS protein, while in the green alga Chlamydomonas reinhardtii LhcSR proteins appear to be exclusively responsible for this role. Interestingly, Chlamydomonas also possesses two PsbS genes, but so far the PsbS protein has not been detected and its biological function is unknown. Here, we reinvestigated the kinetics of gene expression and PsbS and LhcSR3 accumulation in Chlamydomonas during high light stress. We found that, unlike LhcSR3, PsbS accumulates very rapidly but only transiently. In order to determine the role of PsbS in NPQ and photoprotection in Chlamydomonas, we generated transplastomic strains expressing the algal or the Arabidopsis psbS gene optimized for plastid expression. Both PsbS proteins showed the ability to increase NPQ in Chlamydomonas wild-type and npq4 (lacking LhcSR3) backgrounds, but no clear photoprotection activity was observed. Quantification of PsbS and LhcSR3 in vivo indicates that PsbS is much less abundant than LhcSR3 during high light stress. Moreover, LhcSR3, unlike PsbS, also accumulates during other stress conditions. The possible role of PsbS in photoprotection is discussed.
Published: 2016

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