Exposure of a photosystem II complex to chemically generated singlet oxygen results in D1 fragments similar to the ones observed during aerobic photoinhibition

Abstract

Exposure of a PS II core complex to singlet oxygen, generated either chemically in the dark or through the photodynamic action of rose bengal, caused a rapid degradation of D1 protein. Photoinhibitory illumination of the PS II complex, either at 25°C or at 4°C, resulted in D1 protein fragments similar to those observed upon exposure of the PS II complex to singlet oxygen. Histidine, a singlet oxygen scavenger, provided a significant protection of D1 protein against degradation. We therefore suggest that singlet oxygen, which is generated during acceptor-side induced photoinhibition, is responsible for the in vitro fragmentation of D1 protein. © 1994.