Genetic analysis of the dormancy regulator MSDOSR in Mycobacterium smegmatis and characterization of the dosR promoter in Mycobacterium bovis BCG

Abstract

Genetic analysis of the Mycobacterium smegmatis i??msdosR::hyg mutant revealed that the transcription factor, MsdosR, is essential for adaptation to dormancy survival. The functional conservation of the dormancy survival role of MsdosR and its essentiality for anaerobic survival suggests that the core machinery of the mycobacterium dormancy response is conserved in M. smegmatis.Characterization of the dosR locus in M. bovis BCG revealed that the three genes Rv3134c-dosR-Rv3132c are coordinately regulated as an operon and transcriptionally induced in dormant bacilli. Promoter analysis localized the minimal inducible promoter element to a 100-bp region 150 bp upstream of the start of Rv3134c. The minimal inducible promoter element, which consists of a 50-bp response element and a 50-bp basal promoter, is essential and sufficient to confer the promoter activity of the full length fragment. It was demonstrated that DosR is required for expression of the three dosR locus genes, suggesting that the Rv3134c-dosR-Rv3132c operon is autoregulated by DosR.