Flavodiiron proteins associate pH‐dependently with the thylakoid membrane for ferredoxin‐1‐powered O2 photoreduction

• DOI: 10.1111/nph.70114
• Publication Date: 2025-04-05T00:57:52Z
• Authors: Lauri Nikkanen; Serhii Vakal; Michal Hubáček; Anita Santana‐Sán...; Grzegorz Konert; Yingying Wang; Marko Boehm; Kirstin Gutekunst; Tiina A. Salminen; Yagut Allahverdiyeva
• Keywords: Cytochrome b6f complex; Bimolecular fluorescence complementation; Plastoquinone; Synechocystis; Electron acceptor

Flavodiiron proteins (FDPs) catalyse light-dependent reduction of oxygen to water in photosynthetic organisms, creating an electron sink on the acceptor side Photosystem I that protects apparatus. However, ambiguity about donor(s) remains, and molecular mechanisms regulating FDP activity have remained elusive. We employed spectroscopic gas flux analysis transport, bimolecular fluorescence complementation assays for vivo protein-protein interactions model cyanobacterium Synechocystis sp. PCC 6803, silico surface charge modelling. demonstrated ferredoxin-1 interacts with Flv1, Flv2, Flv3, is main donor heterooligomers, which are responsible photoreduction oxygen. Moreover, we revealed heterooligomers dissociate from thylakoid membrane upon alkalisation cytosol, providing first evidence a self-regulatory feedback mechanism allowing dynamic control maintenance redox balance fluctuating environments. Our findings direct implications rationally directing towards desired reactions biotechnological applications.