Structure of a mutated photosystem II complex reveals changes to the hydrogen-bonding network that affect proton egress during O-O bond formation.

ABSTRACT: Photosystem II (PSII) is the water-splitting enzyme of oxygenic photosynthesis. Using light energy, PSII catalytically oxidizes two water molecules to fuel downstream metabolism, forming an O-O bond and releasing O₂ as a byproduct. The reaction mechanism requires the strategic removal of four protons via conserved hydrogen-bonding networks, but these pathways remain poorly understood. Site-directed mutagenesis has been used to study these pathways and the role of specific side chains, such as Lys317 of the D2 subunit. Previous studies showed that the D2-Lys317Ala substitution, which abolishes the flexible hydrogen-bonding -NH₃⁺ group, resulted in delayed O₂ release kinetics and diminished catalytic turnover, suggesting Lys317 has a crucial role i

SUBMITTER: Flesher DA 

PROVIDER: S-EPMC11930075 | biostudies-literature | 2025 Mar

REPOSITORIES: biostudies-literature