Nitrogen Control of Sugar Catabolic Gene Expression in Synechocystis sp. PCC 6803.

Abstract

A group-2 sigma factor sigE in Synechocystis sp. PCC 6803 is induced during nitrogen starvation. Recently, we showed that SigE positively regulated genes involved in sugar catabolism such as glycolysis and oxidative pentose phosphate (OPP) pathway, especially under dark conditions (Osanai et al., 2005). Here, by using microarray and Northern analyses, we found that transcripts for sugar catabolic genes were increased by nitrogen depletion in wild-type cells. These inductions were still observed in the sigE mutant. Then, we constructed the mutant of ntcA, encoding a global nitrogen regulator conserved among cyanobacteria. Northern blot unraveled that the induction of sugar catabolic genes by nitrogen depletion was drastically reduced in the ntcA mutant. The current data suggested redundant regulation for gene expression of sugar catabolic genes in Synechocystis sp. PCC 6803.