Regulation of the Bacillus subtilis bcrC bacitracin resistance gene by two extracytoplasmic function sigma factors.
Bacitracin resistance is normally conferred by either of two major mechanisms, the BcrABC transporter, which pumps out bacitracin, or BacA, an undecaprenol kinase that provides C(55)-isoprenyl phosphate by de novo synthesis. We demonstrate that the Bacillus subtilis bcrC (ywoA) gene, encoding a putative bacitracin transport permease, is an important bacitracin resistance determinant. A bcrC mutant strain had an eightfold-higher sensitivity to bacitracin. Expression of bcrC initiated from a single promoter site that could be recognized by either of two extracytoplasmic function (ECF) sigma factors, sigma(X) or sigma(M). Bacitracin induced expression of bcrC, and this induction was dependent on sigma(M) but not on sigma(X). Under inducing conditions, expression was primarily dependent on sigma(M). As a consequence, a sigM mutant was fourfold more sensitive to bacitracin, while the sigX mutant was only slightly sensitive. A sigX sigM double mutant was similar to a bcrC mutant in sensitivity. These results support the suggestion that one function of B. subtilis ECF sigma factors is to coordinate antibiotic stress responses.
Cao
Min
M
Department of Microbiology, Cornell University, Ithaca, New York 14853-8101, USA.
Helmann
John D
JD
D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001412:Bacillus subtilis / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D001414:Bacitracin / Q000494:pharmacology*; D001426:Bacterial Proteins; D001483:Base Sequence; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
D018528:ATP-Binding Cassette Transporters; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C093265:SigX protein, Bacillus subtilis; D012808:Sigma Factor; C121796:bacitracin permease; D001414:Bacitracin