Antibiotics that inhibit cell wall biosynthesis induce expression of the <i>Bacillus subtilis</i><b>σ</b>^W and <b>σ</b>^M regulons

TLDR

Bacillus subtilis encodes seven extracytoplasmic function sigma factors, including σW, which regulates detoxification and antimicrobial protection, and σM, required for growth under high salt conditions. The study investigates whether antibiotics that inhibit cell wall biosynthesis trigger activation of the σW and σM regulons. Using DNA microarrays, lacZ reporter fusions, and Northern blot analysis, the authors monitored induction of σW‑dependent genes in response to cell‑wall‑biosynthesis inhibitors. Vancomycin induces the σW regulon through σW and its anti‑σ RsiW, independently of AbrB, indicating that RsiW mediates the transcriptional response to cell‑wall stress and that ECF σ factors coordinate antibiosis stress responses with envelope homeostasis.

Abstract

Summary Bacillus subtilis encodes seven extracytoplasmic function (ECF) sigma factors. The σ W regulon includes functions involved in detoxification and protection against antimicrobials, whereas σ M is essential for growth at high salt concentrations. We now report that antibiotics that inhibit cell wall biosynthesis induce both σ W and σ M regulons as monitored using DNA microarrays. Induction of selected σ W ‐dependent genes was confirmed using lacZ reporter fusions and Northern blot analysis. The ability of vancomycin to induce the σ W regulon is dependent on both σ W and the cognate anti‐ σ , RsiW, but is independent of the transition state regulator AbrB. These results suggest that the membrane‐localized RsiW anti‐ σ W factor mediates the transcriptional response to cell wall stress. Our findings are consistent with the idea that one function of ECF σ factors is to coordinate antibiosis stress responses and cell envelope homeostasis.