The stromal side of the cytochrome b6f complex regulates state transitions.

Autor:	Riché A; Aix Marseille Univ, CEA, CNRS, BIAM, Photosynthesis and Environment, F-13115 Saint Paul-Lez-Durance, France., Dumas L; Aix Marseille Univ, CEA, CNRS, BIAM, Photosynthesis and Environment, F-13115 Saint Paul-Lez-Durance, France., Malesinski S; Aix Marseille Univ, CEA, CNRS, BIAM, Photosynthesis and Environment, F-13115 Saint Paul-Lez-Durance, France., Bossan G; Laboratoire de Biologie Physico-Chimique des Protéines Membranaires Unité Mixte de Recherche 7099, Université Paris Cité, Centre National de la Recherche Scientifique, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, F-75005 Paris, France., Madigou C; Laboratoire de Biologie Physico-Chimique des Protéines Membranaires Unité Mixte de Recherche 7099, Université Paris Cité, Centre National de la Recherche Scientifique, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, F-75005 Paris, France., Zito F; Laboratoire de Biologie Physico-Chimique des Protéines Membranaires Unité Mixte de Recherche 7099, Université Paris Cité, Centre National de la Recherche Scientifique, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, F-75005 Paris, France., Alric J; Aix Marseille Univ, CEA, CNRS, BIAM, Photosynthesis and Environment, F-13115 Saint Paul-Lez-Durance, France.
Jazyk:	angličtina
Zdroj:	The Plant cell [Plant Cell] 2024 Oct 03; Vol. 36 (10), pp. 4234-4244.
DOI:	10.1093/plcell/koae190
Abstrakt:	In oxygenic photosynthesis, state transitions distribute light energy between PSI and PSII. This regulation involves reduction of the plastoquinone pool, activation of the state transitions 7 (STT7) protein kinase by the cytochrome (cyt) b6f complex, and phosphorylation and migration of light harvesting complexes II (LHCII). In this study, we show that in Chlamydomonas reinhardtii, the C-terminus of the cyt b6 subunit PetB acts on phosphorylation of STT7 and state transitions. We used site-directed mutagenesis of the chloroplast petB gene to truncate (remove L215b6) or elongate (add G216b6) the cyt b6 subunit. Modified complexes are devoid of heme ci and degraded by FTSH protease, revealing that salt bridge formation between cyt b6 (PetB) and Subunit IV (PetD) is essential to the assembly of the complex. In double mutants where FTSH is inactivated, modified cyt b6f accumulated but the phosphorylation cascade was blocked. We also replaced the arginine interacting with heme ci propionate (R207Kb6). In this modified complex, heme ci is present but the kinetics of phosphorylation are slower. We show that highly phosphorylated forms of STT7 accumulated transiently after reduction of the PQ pool and represent the active forms of the protein kinase. The phosphorylation of the LHCII targets is favored at the expense of the protein kinase, and the migration of LHCII toward PSI is the limiting step for state transitions. Competing Interests: Conflict of interest statement. None declared. (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)
Databáze:	MEDLINE
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