Identification of genetic factors altering the SOS induction of DNA damage-inducible yebG gene in Escherichia coli.

The yebG gene of Escherichia coli is a novel SOS regulon gene, but details of its regulation mechanism and biological function are not yet known. To characterize the regulation of yebG gene as a SOS gene, we identified the genetic factors affecting the SOS induction of yebG gene using yebG-lacZ operon fusion plasmid. We found that the SOS induction of yebG occurs as the cells enter into the stationary growth phase, but its induction is not observed in LB medium in the presence of 1% glucose. A stationary phase SOS induction of the yebG gene does not require the global regulator of stationary phase-specific genes, rpoS, or gyrA functions, but requires cya encoding the adenylate cyclase and hns encoding the histone-like protein H-NS functions. Our results demonstrated that the induction of a DNA damage-inducible yebG gene of E. coli is dependent on cyclic AMP and H-NS.