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Updated: Jan 29, 2026

Reactivation of Demembranated Cell Models in Chlamydomonas reinhardtii
Published on: May 6, 2022
Maximal cyclic electron flow rate is independent of PGRL1 in Chlamydomonas
W J Nawrocki1, B Bailleul2, P Cardol3
1Institut de Biologie Physico-Chimique, UMR 7141 CNRS-Sorbonne Université, 13 rue P. et M. Curie, 75005 Paris, France; Laboratoire de Génétique et Physiologie des Microalgues, Institut de Botanique, Université de Liège, 4, Chemin de la Vallée, B-4000 Liège, Belgium.
Abstract:
Cyclic electron flow (CEF) is defined as a return of the reductants from the acceptor side of Photosystem I (PSI) to the pool of its donors via the cytochrome b6f. It is described to be complementary to the linear electron flow and essential for photosynthesis. However, despite many efforts aimed to characterize CEF, its pathway and its regulation modes remain equivocal, and its physiological significance is still not clear. Here we use novel spectroscopic to measure the rate of CEF at the onset of light in the green alga Chlamydomonas reinhardtii. The initial redox state of the photosynthetic chain or the oxygen concentration do not modify the initial maximal rate of CEF (60 electrons per second per PSI) but rather strongly influence its duration. Neither the maximal rate nor the duration of CEF are different in the pgrl1 mutant compared to the wild type, disqualifying PGRL1 as the ferredoxin-plastoquinone oxidoreductase involved in the CEF mechanism.
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