Bacillus subtilis Tolerance of Moderate Concentrations of Rifampin Involves the σ ^B -Dependent General and Multiple Stress Response

Abstract

Low concentrations of the RNA polymerase inhibitor rifampin added to an exponentially growing culture of Bacillus subtilis led to an instant inhibition of growth. Survival experiments revealed that during the growth arrest the cells became tolerant to the antibiotic and the culture was able to resume growth some time after rifampin treatment. L-[35 S]methionine pulse-labeled protein extracts were separated by two-dimensional polyacrylamide gel electrophoresis to investigate the change in the protein synthesis pattern in response to rifampin. The B -dependent general stress proteins were found to be induced after treatment with the antibiotic. Part of the oxidative stress signature was induced as indicated by the catalase KatA and MrgA. The target protein of rifampin, the ␤ subunit (RpoB) of the DNA-dependent RNA polymerase, and the flagellin protein Hag belonging to the D regulon were also induced. The rifampin-triggered growth arrest was extended in a sigB mutant in comparison to the wild-type strain, and the higher the concentration, the more pronounced this effect was. Activity of the RsbP energy-signaling phosphatase in the B signal transduction network was also important for this protection against rifampin, but the RsbU environmental signaling phosphatase was not required. The sigB mutant strain was less capable of growing on rifampin-containing agar plates. When plated from a culture that had already reached stationary phase without previous exposure to the antibiotic during growth, the survival rate of the wild type exceeded that of the sigB mutant by a factor of 100. We conclude that the general stress response of B. subtilis is induced by rifampin depending on RsbP activity and that loss of SigB function causes increased sensitivity to the antibiotic.The natural habitat of the gram-positive bacterium Bacillus subtilis is the soil-an environment in which stress and starvation are the rule. Not surprisingly B. subtilis has evolved a range of strategies to survive under these hostile conditions. The formation of stress-resistant spores, for example, guarantees long-term survival, while uptake of external DNA in the process of genetic competence may contribute to adaptation by recombination (12). Besides these time-consuming processes B. subtilis is able to quickly develop short-term protection of nongrowing cells against multiple stress conditions, including acidic, alkaline, osmotic, or oxidative stress, heat, or ethanol. A global regulator, the alternative sigma factor B , controls this general stress response. The B regulon contains about 150 genes, some of which have been shown to actively protect or repair macromolecules (see references 12 and 18 for reviews). Under laboratory conditions B is activated by two different groups of stimuli: physical stresses like heat, acid, or ethanol act via the RsbU-dependent pathway, while B activation after glucose or phosphate starvation is RsbP dependent (20,21,24).An alternative sigma factor homologous to B of B. subtilis also exists in Mycobacterium tuberculosi...

σBand σLContribute toListeria monocytogenes10403S Response to the Antimicrobial Peptides SdpC and Nisin

“…The interactive effect observed after the loss of both sigB and sigL may indicate that at least some genes important for recovery and re-growth after nisin exposure are coregulated, either directly or indirectly, by these alternative sigma factors. We also found that re-growth of both the DsigB and the DsigB=DsigL strains after nisin exposure was slower than that of the parent strain, consistent with previous observation that s B is important for B. subtilis recovery after rifampin treatment (Bandow et al, 2002). The overall observation that a deletion of the gene encoding s L (i.e., a single deletion) does not affect L. monocytogenes resistance to nisin is consistent with observations by Dalet et al (2000), who reported that s L (which has also been designated as RpoN) is not involved in L. monocytogenes nisin resistance.…”

RNA Polymerase Mutation Activates the Production of a Dormant Antibiotic 3,3′-Neotrehalosadiamine via an Autoinduction Mechanism in Bacillus subtilis

“…Recently, Bandow et al (25) reported that the addition of Rif to the exponentially growing B. subtilis cells induces B and D regulons, eliciting the cell's tolerance to moderate concentrations of Rif. To test whether these regulon genes were involved in the NTD production, we grew the rpoB ϩ strain TI122 in S7N medium containing varying concentrations (10 -100 g/ml) of Rif.…”

CovS Inactivates CovR and Is Required for Growth under Conditions of General Stress in Streptococcus pyogenes

“…on May 10, 2018 by guest http://jb.asm.org/ mediated response is triggered by apparently unrelated stress conditions indicates that CovS mediates a general or global stress response of GAS. In other bacteria, conditions like low oxygen tension, some types of starvation, and sublethal concentrations of antibiotics also trigger the general stress response (2,4,41). It seems likely that during infection, GAS strains encounter types of stress which we have not tested that also require the CovS-mediated general stress response for growth.…”