Abstract
An extrinsic 33-kDa component protein in photosystem II is essential for photosynthetic oxygen evolution. It is present in all oxygen-evolving organisms, and plays a central role in the stabilization of the manganese cluster. In Arabidopsis thaliana, 33-kDa proteins are encoded by two genes, psbO and psbO2. We characterized the Arabidopsis mutant with a defect in one of them, psbO, and an intact psbO2. The mutant showed considerably retarded growth, suggesting that there is a functional difference between them. Immuno-blot analysis also detected two signals with slightly different mobility in wild type, but only fast moving signal in the mutant. Both PsbO and PsbO2 were expressed as a mature protein fused with GST in E. coli, to characterize their properties. Fused proteins were isolated with affinity chromatography, cleaved with enterokinase and purified ion exchange chromatography. Further characterization is on going.
