Bacillus subtilis paraquat resistance is directed by σM, an extracytoplasmic function sigma factor, and is conferred by YqjL and BcrC

Abstract

A Bacillus subtilis sigM null mutant, lacking the extracytoplasmic function σM protein, was sensitive to paraquat (PQ), a superoxide-generating reagent, but not to the redox stress-inducing compounds hydrogen peroxide, cumene hydroperoxide, t-butyl hydroperoxide, or diamide. Surprisingly, a sigM mutant was only sensitive to superoxide-generating compounds with a dipyridyl ring such as PQ, ethyl viologen, benzyl viologen, and diquat but not to menadione, plumbagin, pyrogallol, or nitrofurantoin. Mutational analysis of candidate σM-regulated genes revealed that both YqjL, a putative hydrolase, and BcrC, a bacitracin resistance protein, were involved in PQ resistance. Expression of yqjL, but not bcrC, from a xylose-inducible promoter restored PQ resistance to the sigM mutant. Copyright © 2005, American Society for Microbiology. All Rights Reserved.