Cross-Reconstitution of Four Extrinsic Proteins From a Red Alga with Higher Plant and Cyanobacterial PSII

Abstract

Oxygen-evolving PSII complex contains a number of intrinsic membrane proteins commonly found from prokaryotic cyanobacteria to eukaryotic higher plants (1). There is, however, a remarkable difference in the extrinsic proteins associated with and functioning in the oxygen-evolving PSII complex among cyanobacteria, red algae and higher plants: In green algal and hi gher plant PSII, three proteins of 33, 23 and 17 kDa are present as extrinsic proteins functioning in maintaining the stability and activity of the oxygen-evolving complex (2). Of these three proteins, only the 33 kDa protein is found in red algal and cyanobacterialPSII but the other two proteins are absent. In contrast, red algal PSII contains three different extrinsic proteins, 20 and 12 kDa proteins and cyt c550 (3), while cyanobacterial PSII contains two proteins, cyt c550 and 12 kDa protein (4).