title: Glucose Induces ECF Sigma Factor Genes,sigXandsigM, Independent of Cognate Anti-sigma Factors through Acetylation of CshA inBacillus subtilis.
abstract: Extracytoplasmic function (ECF) σ factors have roles related to cell envelope and/or cell membrane functions, in addition to other cellular functions. Without cell-surface stresses, ECF σ factors are sequestered by the cognate anti-σ factor, leading to inactivation and the resultant repression of regulons due to the inhibition of transcription of their own genes.Bacillus subtilishas seven ECF σ factors including σXand σMthat transcribe their own structural genes. Here, we report that glucose addition to the medium inducedsigXandsigMtranscription independent of their anti-σ factors. This induction was dependent on an intracellular acetyl-CoA pool. Transposon mutagenesis searching for the mutants showing no induction ofsigXandsigMrevealed that thecshAgene encoding DEAD-box RNA helicase is required for gene induction. Global analysis of the acetylome inB. subtilisshowed CshA has two acetylated lysine residues. We found that in acshAmutant with acetylation-abolishing K to R exchange mutations, glucose induction ofsigXandsigMwas abolished and that glucose addition stimulated acetylation of CshA in the wild type strain. Thus, we present a model wherein glucose addition results in a larger acetyl-CoA pool, probably leading to increased levels of acetylated CshA. CshA is known to associate with RNA polymerase (RNAP), and thus RNAP with acetylated CshA could stimulate the autoregulation ofsigXandsigM. This is a unique model showing a functional link between nutritional signals and the basal transcription machinery.
authors.affiliation: Institute of Oceanic Research and Development, Tokai University Shizuoka, Japan.
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Ogura
authors.affiliation: Department of Bioscience, Saitama University Saitama, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Asai
keywords: RNA polymerase; nutritional signal; protein lysine acetylation; sigma factor; transposon mutagenesis