In vivo electron donation from plastocyanin and cytochrome c6 to PSI in Synechocystis sp. PCC6803

Many cyanobacteria species can use both plastocyanin and cytochrome c6 as lumenal electron carriers to shuttle electrons from the cytochrome b6f to either photosystem I or the respiratory cytochrome c oxidase. In Synechocystis sp. PCC6803 placed in darkness, about 60% of the active PSI centres are b...

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Bibliographic Details
Published in:Biochimica et biophysica acta. Bioenergetics 2021-09, Vol.1862 (9), p.148449-148449, Article 148449
Main Authors: Viola, Stefania, Sellés, Julien, Bailleul, Benjamin, Joliot, Pierre, Wollman, Francis-André
Format: Article
Language:English
Subjects:
Cyanobacteria
Cytochrome c6
Photosystem I
Plastocyanin
Respiration
Online Access:Get full text
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Summary:Many cyanobacteria species can use both plastocyanin and cytochrome c6 as lumenal electron carriers to shuttle electrons from the cytochrome b6f to either photosystem I or the respiratory cytochrome c oxidase. In Synechocystis sp. PCC6803 placed in darkness, about 60% of the active PSI centres are bound to a reduced electron donor which is responsible for the fast re-reduction of P700in vivo after a single charge separation. Here, we show that both cytochrome c6 and plastocyanin can bind to PSI in the dark and participate to the fast phase of P700 reduction, but the fraction of pre-bound PSI is smaller in the case of cytochrome c6 than with plastocyanin. Because of the inter-connection of respiration and photosynthesis in cyanobacteria, the inhibition of the cytochrome c oxidase results in the over-reduction of the photosynthetic electron transfer chain in the dark that translates into a lag in the kinetics of P700 oxidation at the onset of light. We show that this is true both with plastocyanin and cytochrome c6, indicating that the partitioning of electron transport between respiration and photosynthesis is regulated in the same way independently of which of the two lumenal electron carriers is present, although the mechanisms of such regulation are yet to be understood. •Both plastocyanin and cytochrome c6 form a pre-complex with photosystem I in Synechocystis•Fast electron donation to PSI occurs from both plastocyanin and cytochrome c6•The extent of formation of the pre-complex in the dark is not affected by respiration•Electron partitioning between respiration and photosynthesis is regulated similarly in presence of either electron donor
ISSN:0005-2728
1879-2650
DOI:10.1016/j.bbabio.2021.148449