Abstract
Chloroplast gene expression is largely controlled at post-transcriptional steps, and many RNA binding proteins (RNPs) are known to be involved in these regulation. Moreover, the biological function of some chloroplast RNPs can be regulated by phosphorylation. Although cyanobacteria are thought to be the progenitor of chloroplast, little is known about the function of RNPs in the cells. We analyzed the proteins in the ssDNA binding fraction from Synechocystis sp.PCC6803, since many RNPs are known to have affinity for ssDNA. It was found that the levels of two major proteins (20kDa and 30kDa) and the two protein kinase activities in the fraction from continuously illuminated cells are markedly higher than those from cells in dark. Furthermore, it was assumed that 45kDa and 50kDa ssDNA binding proteins detected in continuously illuminated cells may be phospho-proteins. To understand the biological function of these ssDNA binding proteins in cyanobacteria, further analytical studies are underway.
