The Regulation Mechanism And Physiological Function Of Thylakoid Protein Phosphorylation In The Higher Plants

The research on chloroplast protein phosphorylation, which was first found in thylakoid membranes, has been in a progress. Phosphorylation of thylakoid protein is regulated by light via the redox state of electron transfer components in thylakoid membranes and the kinases in the signal transduction pathways controlling this phenomenon emerged recently. However, the regulation mechanism and physiological implication of the thylakoid protein phosphorylation has not been elucidated yet.To investigate the regulatory mechanism of thylakoid protein phosphorylation, the relative levels of thylakoid protein phosphorylation, the redox state of plastoquinone pool, and the steady state protein levels of related kinases were detected in the healthy and tobacco mosaic virus (TMV)-infected leaves from Nicotiana tobacum L.With Western blotting, we observed that the phosphorylation of PSII and LHCII protein was complicatedly affected by TMV infection. TMV-infection has the distinct affects on the phosphorylation of each polypeptide in thylakoid proteins, as well as the phosphorylation of the specific polypeptide in the different light or temperature conditions. As showed by followings: in the TMV-infected leaves, (a) phosphorylation levels of PSII reaction centre proteins D1 and D2, were decreased under any light and temperature conditions; (b) phosphorylation level of another PSII core protein CP43 were increased under the growth conditions, high temperature and low temperature, similar to the healthy ones in the darkness and under the low light and mediated light intensities, but declined under the high light intensity; (c) apart from high temperature under which LHCII phosphorylation level was considerably lower than healthy one, it was increased under any conditions we detected.As showed by the analysis of room temperature chlorophyll fluorescence, the reduction...