PHOTOSYSTEM-II CORE PHOSPHORYLATION HETEROGENEITY AND THE REGULATION OF ELECTRON-TRANSFER IN HIGHER-PLANTS - A REVIEW

Phosphorylation influences the association of proteins which leads to heterogeneous photosystem II core populations upon separation of solubilised photosystem II particles by isoelectrofocusing. In this brief review, through a summary of the properties of the isolated heterogeneous photosystem II complexes, a model on the function of core phosphorylation is presented. An observed consequence of phosphorylation is a modification of the Q(B) pocket concerning herbicide and quinone binding activity, suggesting that it could be a mechanism of electron transfer regulation. Moreover, a main effect of phosphorylation is seen at the level of core protein assembly within stacked regions of higher plants with direct consequences on protein turnover and response to stress conditions. In conclusion, core phosphorylation seems to explain in part the functional heterogeneity of photosystem II seen in vivo.