Anaerobic induction of the alkylation-inducible Escherichia coli aidB gene involves genes of the cysteine biosynthetic pathway.

The Escherichia coli aidB gene is a component of the adaptive response to alkylation damage. This gene is subject to two different forms of induction: an ada-dependent alkylation induction and an ada-independent induction that occurs when cells are grown anaerobically (M. R. Volkert, L. I. Hajec, and D. C. Nguyen, J. Bacteriol. 171:1196-1198, 1989; M. R. Volkert, and D. C. Nguyen, Proc. Natl. Acad. Sci. USA 81:4110-4114, 1984). In this study, we isolated and characterized strains bearing mutations that specifically affect the anaerobic induction pathway. This pathway requires a functional cysA operon, which encodes sulfate permease. Mutations in cysA block this pathway of aidB induction. In contrast, mutations in either cysH, cysD, cysN, or cysC result in elevated levels of aidB expression during aerobic growth. These results indicate that the sulfate transport genes perform a role in anaerobic induction of the aidB gene and suggest that growth under anaerobic conditions may modify either the function or the expression of gene products encoded by the cysA operon.