A Group 2 Sigma Factor Activates the Oxidative Pentose Phosphate Pathway and Other Sugar Catabolism in Synechocystis sp. PCC 6803.

Abstract

The genome of Synechocystis sp. PCC 6803 cells encodes four group-2 sigma factors including sigE, and in this study, we have found that a mutant deficient in SigE fails to proliferate under the heterotrophic growth condition. Microarray and Northern analyses demonstrated that the transcript levels of oxidative pentose phosphate (OPP) pathway, glycolysis, and glycogen catabolism were reduced in the sigE mutant under the normal growth condition, and activities of two significant enzymes for the OPP pathway, glucose-6-phosphate dehydrogenase and 6-phophogluconate dehydrogenase, were actually decreased by the sigE disruption. Previously, Muro-Pastor demonstrated that SigE was induced by nitrogen deprivation (Muro-Pastor et al., 2001). We showed here that the sugar catabolic genes were actually activated by nitrogen depletion dependent on SigE.