The PsbW protein stabilizes the supramolecular organization of photosystem II in higher plants
PsbW, a 6.1-kDa low-molecular-weight protein, is exclusive to photosynthetic eukaryotes, and associates with the photosystem II (PSII) protein complex. In vivo and in vitro comparison of Arabidopsis thaliana wild-type plants with T-DNA insertion knock-out mutants completely lacking the PsbW protein, or with antisense inhibition plants exhibiting decreased levels of PsbW, demonstrated that the loss of PsbW destabilizes the supramolecular organization of PSII. No PSII-LHCII supercomplexes could be detected or isolated in the absence of the PsbW protein. These changes in macro-organization were accompanied by a minor decrease in the chlorophyll fluorescence parameter FV/FM, a strongly decreased PSII core protein phosphorylation and a modification of the redox state of the plastoquinone (PQ) pool in dark-adapted leaves. In addition, the absence of PsbW protein led to faster redox changes in the PQ pool, i.e. transitions from state 1 to state 2, as measured by changes in stationary fluorescence (FS) kinetics, compared with the wild type. Despite these dramatic effects on macromolecular structure, the transgenic plants exhibited no significant phenotype under normal growth conditions. We suggest that the PsbW protein is located close to the minor antenna of the PSII complex, and is important for the contact and stability between several PSII-LHCII supercomplexes.
Document Type: Research Article
Affiliations: 1: Institute of Plant Biology, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, 6726 Szeged, Hungary 2: Department of Biophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, The Netherlands 3: Lehrstuhl für Botanik, Department Biologie I; Ludwig-Maximilians-Universität München 82152 Planegg-Martinsried, Germany 4: Department of Photochemistry and Molecular Science, Molecular Biomimetics, Ångström Laboratory, Box 523 Uppsala University, SE-751 20 Uppsala, Sweden 5: Department of Chemistry, Umeå Plant Science Centre (UPSC), Umeå University, SE-901 87 Umeå, Sweden
Publication date: February 1, 2011