Garcia-Cerdin JG, Sveshnikov D, Dewer D., Jansson S, Funk C, Schröder WP
Antisense inhibition of the PsbX protein affects PSII integrity in higher plant Arabidopsis thaliana
Plant and Cell Physiology: 2009 50(2):191-202

Abstract
Photosystem II, the oxygen-evolving complex of photosynthetic organisms, contains an intriguingly large number of low molecular weight proteins. PsbX, one of these proteins, is ubiquitous in Photosystem II complexes of cyanobacteria and plants. In previous studies, deletion of the PsbX protein in cyanobacteria has not resulted in clear phenotypic changes. Here we report the construction of an anti-sense (AS-PsbX) line in Arabidopsis thaliana, with less than 10% of wild type PsbX levels. AS-PsbX plants are capable of photoautotrophic growth, but biochemical, biophysical, and immunological evidence demonstrates that reduction of PsbX contents leads to reduced levels of functional assembled PSII core complexes, while the light harvesting antennae are not affected. In addition, levels of phosphorylation of the core proteins D1, D2 and CP43 are severely reduced in the anti-sense plants, relative to wild type counterparts. We conclude that PsbX is important for accumulation of functional PSII.

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