Regulation of the Bacillus subtilis bcrC Bacitracin Resistance Gene by Two Extracytoplasmic Function σ Factors

Abstract

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 eightfoldhigher sensitivity to bacitracin. Expression of bcrC initiated from a single promoter site that could be recognized by either of two extracytoplasmic function (ECF) factors, X or M . Bacitracin induced expression of bcrC, and this induction was dependent on M but not on X . Under inducing conditions, expression was primarily dependent on 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 factors is to coordinate antibiotic stress responses.

Functional Analysis of the YvrGHb Two-Component System ofBacillus subtilis: Identification of the Regulated Genes by DNA Microarray and Northern Blot Analyses

“…The transcription of bcrC is regulated by SigX and SigM. 38) Under inducing conditions, expression was primarily dependent on SigM but not on SigX. 38) We also performed an antibiotic sensitivity test for the ÁsigX and ÁsigM strains (Table 5).…”

“…38) Under inducing conditions, expression was primarily dependent on SigM but not on SigX. 38) We also performed an antibiotic sensitivity test for the ÁsigX and ÁsigM strains (Table 5). Since only SigM controls the response to the bacitracin of bcrC, an increase in susceptibility was detected only in the ÁsigM strain.…”

“…10,38) The existence of ABC transporters, such as BcrC 38) and BceAB, 10) was important in the bacitracin resistance. The transcription of bcrC is regulated by SigX and SigM.…”

Transcriptional analysis of the ylaABCD operon of Bacillus subtilis encoding a sigma factor of extracytoplasmic function family

“…The functions of SigV, SigZ and YlaC remain to be elucidated, while four sigmas, SigM, SigW, SigX, and SigY, have been studied well. They are required for stresses caused by salt, heat, ethanol, acid, cell wall antibiotics, superoxide, alkali, and nitrogen-starvation (Horsburg and Moir, 1999;Thackray and Moir, 2003;Cao et al, 2002B;Cao and Helmann, 2002;Cao et al, 2003;Tojo et al, Edited by Fujio Kawamura * Corresponding author. E-mail: ysadaie@molbiol.saitama-u.ac.jp Wiegert et al, 2001).…”

Identification of Bacillus subtilis σW‐dependent genes that provide intrinsic resistance to antimicrobial compounds produced by Bacilli

“…Extracytoplasmic function (ECF) σ factors often control functions related to the cell surface or transport (reviewed by Helmann, 2002 , encodes an undecaprenyl pyrophosphate phosphatase that participates in bacitracin resistance (Cao and Helmann, 2002;Bernard et al ., 2005). The σ X regulon includes two operons that function to decrease the net negative charge of the cell envelope by increasing the synthesis of phosphatidylethanolamine and the D -alanylation of teichoic acids.…”