Amino acid residues that modulate the properties of tyrosine Y-Z and the manganese cluster in the water oxidizing complex of photosystem II

The catalytic site for photosynthetic water oxidation is embedded in a prot ein matrix consisting of nearly 30 different polypeptides. Residues from se veral of these polypeptides modulate the properties of the tetrameric Mn cl uster and the redox-active tyrosine residue, Y-Z, that are located at the c atalytic site. However, most or all of the residues that interact directly with Y-Z and the Mn cluster appear to be contributed by the D1 polypeptide. This review summarizes our knowledge of the environments of Y-Z and the Mn cluster as obtained from the introduction of site-directed, deletion, and other mutations into the photosystem II polypeptides of the cyanobacterium Synechocystis sp. PCC 6803 and the green alga Chlamydomonas reinhardtii. (C ) 2001 Elsevier Science B.V. All rights reserved.