Identification of sigma(B)-dependent genes in Bacillus subtilis using a promoter consensus-directed search and oligonucleotide hybridization

A consensus-directed search for sigma(B) promoters was used to locate poten tial candidates for new sigma(B)-dependent genes in Bacillus subtilis. Scre ening of those candidates by oligonucleotide hybridizations with total RNA from exponentially growing or ethanol-stressed cells of the wild type as we ll as a sigB mutant revealed 22 genes that required sigma(B) for induction by ethanol. Although almost 50% of the proteins encoded by the newly discov ered sigma(B)-dependent stress genes seem to be membrane localized, biochem ical functions have so far not been defined for any of the gene products. A llocation of the genes to the sigma(B)-dependent stress regulon may indicat e a potential function in the establishment of a multiple stress resistance . AIdY and YhdF show similarities to NAD(P)-dependent dehydrogenases and Yd bP to thioredoxins, supporting our suggestion that sigma(B)-dependent prote ins may be involved in the maintenance of the intracellular redox balance a fter stress.