Investigation of the in vivo structure of the oxygen-evolving Photosystem II (PS II) core complex in Synechococcus elongatus

摘要

Oxygen evolution is a result of concerted redox reactions in PS II core complex having wellorganized multisubunit structure. Assuming that eleven subunit molecules associate to form PS II core complex on the basis of 1:1 stoichiometry (Ikeuchi and Inoue 1988), the mass for the entire molecule could be estimated to be about 230 kDa. Corresponding size for PS II core complexes has been obtained from the size- and shape-analyses of the detergentsolubilized PS II complexes. We purified oxygen-evolving PS II core complexes from thecells of Synechococcus elongatus, a thermophilic cyanobacterium (Sugiura and Inoue 1999). The complexes held active oxygen-evolving functions for longer than two weeks even at room temperature indicating its very stable functional structure. Gel permeation chromatography shows purity and the size for the complexes, which is about twice as large asthe 230-kDa fundamental PS II unit.