title: Involvement of state transitions in the switch between linear and cyclic electron flow in Chlamydomonas reinhardtii.
abstract: The energetic metabolism of photosynthetic organisms is profoundly influenced by state transitions and cyclic electron flow around photosystem I. The former involve a reversible redistribution of the light-harvesting antenna between photosystem I and photosystem II and optimize light energy utilization in photosynthesis whereas the latter process modulates the photosynthetic yield. We have used the wild-type and three mutant strains of the green alga Chlamydomonas reinhardtii--locked in state I (stt7), lacking the photosystem II outer antennae (bf4) or accumulating low amounts of cytochrome b6f complex (A-AUU)--and measured electron flow though the cytochrome b6f complex, oxygen evolution rates and fluorescence emission during state transitions. The results demonstrate that the transition from state 1 to state 2 induces a switch from linear to cyclic electron flow in this alga and reveal a strict cause-effect relationship between the redistribution of antenna complexes during state transitions and the onset of cyclic electron flow.
authors.affiliation: Centro di Studio del C.N.R. sulla Biologia Cellulare e Molecolare delle Piante, Università degli Studi di Milano, 20161 Milano, Italy. giovanni.finazzi@unimi.it
authors.forename: Giovanni
authors.initials: G
authors.lastname: Finazzi
authors.forename: Fabrice
authors.initials: F
authors.lastname: Rappaport
authors.forename: Alberto
authors.initials: A
authors.lastname: Furia
authors.forename: Mark
authors.initials: M
authors.lastname: Fleischmann
authors.forename: Jean-David
authors.initials: JD
authors.lastname: Rochaix
authors.forename: Francesca
authors.initials: F
authors.lastname: Zito
authors.forename: Giorgio
authors.initials: G
authors.lastname: Forti
mesh_terms: D000818:Animals; D016825:Chlamydomonas reinhardtii / Q000737:chemistry / Q000502:physiology*; D003580:Cytochromes / Q000737:chemistry; D045348:Cytochromes f; D004579:Electron Transport / Q000502:physiology; D004583:Electrons; D005453:Fluorescence; D009154:Mutation; D010084:Oxidation-Reduction; D010788:Photosynthesis / Q000502:physiology*
chemical_list: D003580:Cytochromes; D045348:Cytochromes f