Abstract
In Synechocystis sp. PCC 6803, decrease of photosystem I (PSI) content is observed under high-light conditions. Since the pmgA-disrupted mutant, which has defect in this regulation, shows severe growth inhibition under high light, the regulation achieved by PmgA is indispensable for growth under high-light conditions. However, the function of PmgA is totally unknown, except that PmgA shows weak homology to RsbW, an anti-sigma factor in Bacillus subtilis. We found that two promoters of psaAB encoding reaction center subunits of PSI shows higher activity under high-light conditions in the pmgA mutant than in WT cells, although the light-responsive mechanism of the two promoters is totally different. This result suggests PmgA functions as an anti-sigma factor. Now, by DNA microarray analysis, we are trying to identify genes whose expression is under the control of PmgA.
