Cyclic Electron Flow-Coupled Proton Pumping in Synechocystis sp. PCC6803 Is Dependent upon NADPH Oxidation by the Soluble Isoform of Ferredoxin:NADP-Oxidoreductase.

ABSTRACT: Ferredoxin:NADP-oxidoreductase (FNR) catalyzes the reversible exchange of electrons between ferredoxin (Fd) and NADP(H). Reduction of NADP⁺ by Fd via FNR is essential in the terminal steps of photosynthetic electron transfer, as light-activated electron flow produces NADPH for CO₂ assimilation. FNR also catalyzes the reverse reaction in photosynthetic organisms, transferring electrons from NADPH to Fd, which is important in cyanobacteria for respiration and cyclic electron flow (CEF). The cyanobacterium Synechocystis sp. PCC6803 possesses two isoforms of FNR, a large form attached to the phycobilisome (FNR_L) and a small form that is soluble (FNR_S). While both isoforms are capable of NADPH oxidation or NADP⁺ reduction, FNR_L<

SUBMITTER: Miller NT 

PROVIDER: S-EPMC9144156 | biostudies-literature | 2022 Apr

REPOSITORIES: biostudies-literature