Structural coupling between the oxygen-evolving Mn cluster and a tyrosine residue in photosystem II as revealed by Fourier transfrom infrared spectroscopy

The presence of a structural coupling between redox-active tyrosine 161 of the D1 polypeptide (Y(sub z)) and the manganese (Mn) cluster in an intact oxygen-evolving complex was investigated through Fourier transform infrared spectroscopy. The linkage coupling formed a proton transfer pathway and an indirect proton transfer from substrate water to Yz. In S-state transition, the hydrogen bond between Yz and Mn catalyzed the electron transfer from the Mn cluster to Yz.