1. Chloroplast remodeling during state transitions in Chlamydomonas reinhardtii as revealed by noninvasive techniques in vivo
- Author
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Lucas Moyet, Renáta Ünnep, Kenji Takizawa, Ryutaro Tokutsu, Lionel Porcar, Jun Minagawa, Dimitris Petroutsos, Gergely Nagy, Győző Garab, Ottó Zsiros, Giovanni Finazzi, Laboratory for Neutron Scattering and Imaging [Paul Scherrer Institute] (LNS), Paul Scherrer Institute (PSI), Wigner Research Centre for Physics [Budapest], Hungarian Academy of Sciences (MTA), Institut Laue-Langevin (ILL), ILL, Institute of Plant Biology, Biological Research Centre [Budapest] (BRC), Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), Division of Environmental Photobiology, National Institute for Basic Biology [Okazaki], Laboratoire de physiologie cellulaire végétale (LPCV), Université Joseph Fourier - Grenoble 1 (UJF)-Institut National de la Recherche Agronomique (INRA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Grants EU FP MC ITN 'HARVEST', OTKA/NKTH-NIH (60003-00), NKTH-NIH (NAP-VENEUS05), Marie Curie Initial Training Network Accliphot (FP7-PEPOPLE-2012-ITN, 316427), Japan Society for Grants-in-Aid for Research Activity Start-up (23870033), Funding Programfor Next GenerationWorld- Leading Researchers (GS026), the New Energy and Industrial Technology Development Organization for the strategic development of next-generation bioenergy utilization technology (P07015), Laboratory for Neutron Scattering, Université Joseph Fourier - Grenoble 1 (UJF)-Institut National de la Recherche Agronomique (INRA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-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)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
- Subjects
Circular dichroism ,Chloroplasts ,Absorption spectroscopy ,Light-Harvesting Protein Complexes ,photosystem ,protein-protein interactions ,Chlamydomonas reinhardtii ,plant ,macromolecular substances ,Biochemistry ,Models, Biological ,Thylakoids ,Protein–protein interaction ,Light-harvesting complex ,Scattering, Small Angle ,state transitions ,[SDV.BV]Life Sciences [q-bio]/Vegetal Biology ,[SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology ,Photosystem ,light harvesting complex ,Multidisciplinary ,photosynthesis ,biology ,Photosystem I Protein Complex ,Circular Dichroism ,food and beverages ,Photosystem II Protein Complex ,thylakoid membrane ,Biological Sciences ,biology.organism_classification ,green algae ,Chloroplast ,Crystallography ,Neutron Diffraction ,Thylakoid ,light acclimation mechanism ,Mutation ,Biophysics - Abstract
International audience; Plants respond to changes in light quality by regulating the absorption capacity of their photosystems. These short-term adaptations use redox-controlled, reversible phosphorylation of the light-harvesting complexes (LHCIIs) to regulate the relative absorption cross-section of the two photosystems (PSs), commonly referred to as state transitions. It is acknowledged that state transitions induce substantial reorganizations of the PSs. However, their consequences on the chloroplast structure are more controversial. Here, we investigate how state transitions affect the chloroplast structure and function using complementary approaches for the living cells of Chlamydomonas reinhardtii. Using small-angle neutron scattering, we found a strong periodicity of the thylakoids in state 1, with characteristic repeat distances of ∼200 Å, which was almost completely lost in state 2. As revealed by circular dichroism, changes in the thylakoid periodicity were paralleled by modifications in the long-range order arrangement of the photosynthetic complexes, which was reduced by ∼20% in state 2 compared with state 1, but was not abolished. Furthermore, absorption spectroscopy reveals that the enhancement of PSI antenna size during state 1 to state 2 transition (∼20%) is not commensurate to the decrease in PSII antenna size (∼70%), leading to the possibility that a large part of the phosphorylated LHCIIs do not bind to PSI, but instead form energetically quenched complexes, which were shown to be either associated with PSII supercomplexes or in a free form. Altogether these noninvasive in vivo approaches allow us to present a more likely scenario for state transitions that explains their molecular mechanism and physiological consequences.
- Published
- 2014
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