title: State transitions redistribute rather than dissipate energy between the two photosystems in Chlamydomonas.
abstract: Photosynthesis converts sunlight into biologically useful compounds, thus fuelling practically the entire biosphere. This process involves two photosystems acting in series powered by light harvesting complexes (LHCs) that dramatically increase the energy flux to the reaction centres. These complexes are the main targets of the regulatory processes that allow photosynthetic organisms to thrive across a broad range of light intensities. In microalgae, one mechanism for adjusting the flow of energy to the photosystems, state transitions, has a much larger amplitude than in terrestrial plants, whereas thermal dissipation of energy, the dominant regulatory mechanism in plants, only takes place after acclimation to high light. Here we show that, at variance with recent reports, microalgal state transitions do not dissipate light energy but redistribute it between the two photosystems, thereby allowing a well-balanced influx of excitation energy.
authors.affiliation: Institut de Biologie Physico-Chimique, UMR 7141 CNRS-UPMC, 13 rue P. et M. Curie 75005, Paris, France.
authors.forename: Wojciech J
authors.identifier: 0000-0001-5124-3000
authors.initials: WJ
authors.lastname: Nawrocki
authors.affiliation: Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Via Celoria 26, 20133 Milan, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Santabarbara
authors.affiliation: Institut de Biologie Physico-Chimique, UMR 7141 CNRS-UPMC, 13 rue P. et M. Curie 75005, Paris, France.
authors.forename: Laura
authors.initials: L
authors.lastname: Mosebach
authors.affiliation: Institut de Biologie Physico-Chimique, UMR 7141 CNRS-UPMC, 13 rue P. et M. Curie 75005, Paris, France.
authors.forename: Francis-André
authors.initials: FA
authors.lastname: Wollman
authors.affiliation: Institut de Biologie Physico-Chimique, UMR 7141 CNRS-UPMC, 13 rue P. et M. Curie 75005, Paris, France.
authors.forename: Fabrice
authors.identifier: 0000-0001-9377-4934
authors.initials: F
authors.lastname: Rappaport
mesh_terms: D000064:Acclimatization; D002696:Chlamydomonas / Q000378:metabolism*; D008027:Light; D058086:Microalgae / Q000378:metabolism*; D010788:Photosynthesis; D045331:Photosystem I Protein Complex / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000378:metabolism*
chemical_list: D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex