Elucidation of regulatory elements that control damage induction and competence induction of the Bacillus subtilis SOS system

Abstract

A novel consensus sequence (GAAC-N4-GTTC) has been identified within the promoter regions of DNA damage-inducible (din) genes from Bacillus subtilis. This sequence has been proposed to function as an operator site that is required for regulation of the SOS system of B. subtilis. To test this hypothesis, a deletion analysis of the dinA and recA promoter regions was utilized. A single consensus sequence is sufficient and necessary for damage-inducible regulation of the dinA and recA promoters. Deletion of the consensus sequences upstream of these promoters derepressed their expression under uninduced conditions. In addition, this deletion analysis has further defined sequences upstream of the recA promoter that are required for expression of the recA gene in cells that have differentiated to the state of natural competence. Northern (RNA) hybridization and S1 nuclease protection experiments have demonstrated that the damage-inducible and competence-inducible recA-specific transcripts initiate from a single promoter. Mutations within the comA, srfA, and degU loci each completely abolish the competence-inducible expression of the recA gene.