Overexpression of chloroplastic glycerol-3-phosphate acyltransferase gene (LeGPAT) in tomato increased
cis-unsaturated fatty acid content in phosphatidylglycerol (PG) of thylakoid membrane. By contrast, suppressing the expression of LeGPAT decreased the content of cis-unsaturated fatty acid in PG. Under salt stress, sense transgenic plants exhibited higher activities of chloroplastic antioxidant enzymes, lower content of reactive oxygen species (ROS) and less ion leakage compared with the wild type (WT) plants. The net photosynthetic rate (PN) and the maximal photochemical efficiency (Fv/Fm) of photosystem II (PSII) decreased more slightly in sense lines but more markedly in the antisense ones, compared to WT. D1 protein, located in the reactive center of the PSII, is the primary target of photodamage and has the highest turnover rate in the chloroplast. Under salt stress, compared with WT, the content of D1 protein decreased slightly in sense lines and significantly in the antisense ones. In the presence of streptomycin (SM), the net degradation of the damaged D1 protein was faster in sense lines than in other plants. These results suggested that, under salt-stress conditions, increasing
cis-unsaturated fatty acids in PG by overexpression of LeGPAT can alleviate PSII photoinhibition by accelerating the repair of D1 protein and improving the activity of antioxidant enzymes in chloroplasts. and Y. L. Sun ... [et al.].
The PsbH protein belongs to a group of small protein subunits of the photosystem 2 (PS2) complex and genes encoding PsbH homologues have been so far found in all studied oxygenic phototrophs. This single helix membrane protein is important for the proper function of the PS2 acceptor side and for stable assembly of PS2. Its hypothetical function as an analogue of the H subunit of the bacterial reaction centre as well as a putative role of its phosphorylation is evaluated. and J. Komenda, D. Štys, L. Lupínková.
In plants external stimuli are perceived through a cascade of signals and signal transduction pathways. Protein phosphorylation and de-phosphorylation is one of the most important transduction paths for the perception of signals in plants. The highest concentrations of plant phospho-proteins are located in chloroplasts. This facilitates the protection of thylakoid membranes from stress-induced damage and augments adaptive strategies in plants. In this review, the protein kinases associated with phosphorylation of thylakoid membrane protein, and the adaptive changes in thylakoid membrane architecture and developmental cues are given. The presence of membrane bound kinases in thylakoid membranes have evolutionary implications for the signal transduction pathways and the photosynthetic gene expression for thylakoid membrane protein dynamics. and A. N. Misra, A. K. Biswal.