1. State transitions in the cyanobacterium Synechococcus elongatus 7942 involve reversible quenching of the photosystem II core
- Author
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Paul C. Struik, Herbert van Amerongen, Emilie Wientjes, Diana Kirilovsky, Reza Ranjbar Choubeh, 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), Mécanismes régulateurs chez les organismes photosynthétiques (MROP), 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)-Institut de Biologie Intégrative de la Cellule (I2BC), and 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)
- Subjects
0106 biological sciences ,0301 basic medicine ,Materials science ,Crop Physiology ,Photosystem II ,[SDV]Life Sciences [q-bio] ,Biophysics ,Photosystem I ,Photochemistry ,Cyanobacteria ,porphyridium-cruentum ,01 natural sciences ,7. Clean energy ,Biochemistry ,Fluorescence spectroscopy ,synechocystis pcc 6803 ,03 medical and health sciences ,chemistry.chemical_compound ,Photosystem ,VLAG ,Time-resolved fluorescence spectroscopy ,wild-type ,photosynthesis ,excitation-energy ,Phycobiliprotein ,less mutant ,picosecond fluorescence spectroscopy ,Cell Biology ,PE&RC ,phycobilisome ,030104 developmental biology ,Biofysica ,chemistry ,State transitions ,synechococcus sp ,Excited state ,Chlorophyll ,cells ,Phycobilisome ,EPS ,010606 plant biology & botany - Abstract
International audience; Cyanobacteria use chlorophyll and phycobiliproteins to harvest light. The resulting excitation energy is delivered to reaction centers (RCs), where photochemistry starts. The relative amounts of excitation energy arriving at the RCs of photosystem I (PSI) and II (PSII) depend on the spectral composition of the light. To balance the excitations in both photosystems, cyanobacteria perform state transitions to equilibrate the excitation energy. They go to state I if PSI is preferentially excited, for example after illumination with blue light (light I), and to state II after illumination with green-orange light (light II) or after dark adaptation. In this study, we performed 77-K time-resolved fluorescence spectroscopy on wild-type Synechococcus elongatus 7942 cells to measure how state transitions affect excitation energy transfer to PSI and PSII in different light conditions and to test the various models that have been proposed in literature. The time-resolved spectra show that the PSII core is quenched in state II and that this is not due to a change in excitation energy transfer from PSII to PSI (spill-over), either direct or indirect via phycobilisomes.
- Published
- 2018