Characterization and complementation of a psbR mutant in Arabidopsis thaliana

In this communication we have characterized an Arabidopsis thaliana mutant which lacks the PsbR protein of Photosystem II and complemented its phenotype by introduction and expression of a C-terminally His6-tagged PsbR protein. Absence of the PsbR protein leads to decreased levels of the PsbP, PsbQ and D2 proteins associated with Photosystem II membranes. Functional defects in the mutant were localized principally to the reducing-side of the photosystem and included slowing of electron transfer from QA- to QB. These defects were almost fully corrected in transgenic plants containing the C-terminally His6-tagged PsbR protein. We hypothesize that the functional defects observed in the mutant were due to defective assembly and/or binding of the PsbP and PsbQ components to Photosystem II in the absence of the PsbR protein.