In vivo electron donation from plastocyanin and cytochrome c6 to PSI in Synechocystis sp. PCC6803.
Biochim Biophys Acta Bioenerg
; 1862(9): 148449, 2021 09 01.
Article
in En
| MEDLINE
| ID: mdl-34004195
ABSTRACT
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.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Plastocyanin
/
Cytochromes c6
/
Photosystem I Protein Complex
/
Synechocystis
Language:
En
Journal:
Biochim Biophys Acta Bioenerg
Year:
2021
Document type:
Article
Affiliation country:
United kingdom