Abstract
Photosystem II (PSII) is composed of membrane intrinsic and extrinsic protein subunits. While most intrinsic subunits are encoded by the chloroplast genome, extrinsic subunits, known as oxygen-evolving complex (OEC), are nuclear-encoded protein in higher plants. In addition to authentic OEC proteins in PSII, higher plants have number of OEC homologs in thylakoid lumen, indicating that genes for OEC proteins were susceptible to diversification during endosymbiosis and subsequent gene transfer to the host nucleus. However, molecular function of OEC homologs has not been elucidated. In this study, we investigated mRNA expression profiles of Arabidopsis OEC homologs using the microarray data from AtgenExpress. Our bioinformatic analysis suggests that some OEC homologs would be involved in the regulation of PSII function, and others in NAD(P)H dehydrogenase complex. The validity of our in silico analysis has been proven in vivo by using corresponding Arabidopsis mutants (Ishihara et al. [2007] Plant Physiol. 145:668-679).
