title: Cyclic electron flow is redox-controlled but independent of state transition.
abstract: Photosynthesis is the biological process that feeds the biosphere with reduced carbon. The assimilation of CO2 requires the fine tuning of two co-existing functional modes: linear electron flow, which provides NADPH and ATP, and cyclic electron flow, which only sustains ATP synthesis. Although the importance of this fine tuning is appreciated, its mechanism remains equivocal. Here we show that cyclic electron flow as well as formation of supercomplexes, thought to contribute to the enhancement of cyclic electron flow, are promoted in reducing conditions with no correlation with the reorganization of the thylakoid membranes associated with the migration of antenna proteins towards Photosystems I or II, a process known as state transition. We show that cyclic electron flow is tuned by the redox power and this provides a mechanistic model applying to the entire green lineage including the vast majority of the cases in which state transition only involves a moderate fraction of the antenna.
authors.affiliation: Institut de Biologie Physico-Chimique, UMR 7141 CNRS-UPMC, 13 rue P et M Curie, 75005 Paris, France.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Takahashi
authors.forename: Sophie
authors.initials: S
authors.lastname: Clowez
authors.forename: Francis-André
authors.initials: FA
authors.lastname: Wollman
authors.forename: Olivier
authors.initials: O
authors.lastname: Vallon
authors.forename: Fabrice
authors.initials: F
authors.lastname: Rappaport
mesh_terms: D002696:Chlamydomonas / Q000378:metabolism; D004579:Electron Transport; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis; D045331:Photosystem I Protein Complex / Q000378:metabolism
chemical_list: D045342:Light-Harvesting Protein Complexes; D045331:Photosystem I Protein Complex; D010100:Oxygen