Structural dynamics within the water and proton channels of Photosystem II

Light-driven oxidation of water to molecular oxygen is catalyzed by the oxygen-evolving complex (OEC) in Photosystem II (PSII). This multi-electron, multi-proton catalysis requires the transport of water substrate to and proton egress from the OEC. We have studied the room temperature time-resolved crystal structures of PSII to investigate possible transport channels using X-ray free-electron laser (XFEL) crystallography. The structural changes observed will be discussed and the possible implications for the mechanism of dioxygen formation