The PsbM (3.9 kDa) and PsbY (4.2 kDa) proteins are membrane-spanning, single-helix, subunits associated with the chlorophyll-binding CP47 pre-complex of photosystem II (PSII). Removal of PsbM resulted in accumulation of PSII pre-assembly complexes and impaired electron transfer between the primary (QA) and secondary (QB) plastoquinone electron acceptors of PSII indicating that the QB-binding site and bicarbonate binding to the non-heme iron were altered in this strain. Removal of PsbY alone had only a minor impact on PSII activity but deleting PsbY in the PsbM background led to additional modification of the acceptor side resulting in PsbM:PsbY cells being susceptible to photodamage and this required protein synthesis for recovery. Addition of bicarbonate was able to compensate for the light-induced damage in PsbM:PsbY cells potentially re-occupying the modified bicarbonate-binding site in the PsbM:PsbY strain and complementation of PsbM:PsbY cells with the psbY gene restored the PsbM phenotype., S. Biswas, J. J. Eaton-Rye., and Obsahuje bibliografické odkazy