Separate mechanisms activate sigma B of Bacillus subtilis in response to environmental and metabolic stresses

Alternative transcription factor sigmaSB of Staphylococcus aureus: characterization and role in transcription of the global regulatory locus sar

“…A 207-bp PstI-EcoRI fragment was isolated from pV312, purified by electroelution from a 10% polyacrylamide gel, and used as a template for assay of transcription from the B. subtilis P B promoter of the sigB operon. The calculated size of the transcript should be 36 nucleotides (6,37). A 99-bp synthetic DNA fragment corresponding to the P B promoter region of the sigB operon of S. aureus was used as a template.…”

“…B , identified in sporulating Bacillus subtilis, is the first member of the alternate factors to be reported in prokaryotes (20,21). Much has been learnt recently about the regulation of expression of the sigB operon and the modulation of the function of the SigB ( B ) protein in response to changing stress (entry into stationary growth phase, nutrient depletion, and presence of uncouplers of oxidative phosphorylation) and environmental stress (heat shock and osmotic shock) in B. subtilis (2,6,8,22,36,37,41).The emergence of multiple-drug-resistant, highly pathogenic strains of Staphylococcus aureus poses a serious threat for human and animal health management of infected subjects. S. aureus causes a number of infections ranging from superficial skin abscesses to life-threatening systemic diseases (e.g., toxic shock syndrome and osteomyelitis) (17,25,38).…”

Heat‐shock and general stress response in Bacillus subtilis

“…, 1990;Benson and Haldenwang, 1993a,b;Boylan et al, 1993a;Völker et al, 1994;1995b). This conclusion, originally drawn from the analysis of a sigB mutant, is reinforced by the fact that the s B -regulon can be induced (without being exposed to stress or starvation) when a sigB operon with a null mutation in the primary negative regulator RsbW (see below) is placed under the control of the IPTG-inducible P spac promoter (J. Bernhardt, U. Völker, H. Mach and M. Hecker, unpublished).…”

“…Transcription initiating at this promoter contributes to the basal level of expression of the four downstream genes of the operon (rsbV, rsbW, sigB and rsbX ) and is responsible for the sudden increase in the level of the corresponding proteins in response to stress and starvation (Kalman et al, 1990;Benson and Haldenwang, 1992;Benson and Haldenwang, 1993a;Boylan et al, 1993a;Völker et al, 1994;1995b). The genes rsbR, rsbS, rsbT, rsbU, rsbV, rsbW and rsbX encode proteins involved in the regulation of the activity of s B (regulators of sigma B; Benson and Haldenwang, 1992;Boylan et al, 1992;Kang et al, 1995;Völker et al, 1995a;Wise and Price, 1995).…”

“…Entry into the stationary phase in rich medium, exhaustion of glucose, phosphate or oxygen, treatment of bacteria with an uncoupler of oxidative phosphorylation (CCCP) or the introduction of a mutation in the ATP synthetase all belong to the first class of stimuli which trigger the activation of s B by a RsbU-independent pathway (Völker et al, 1995b). It is likely that all these conditions cause a drop in the intracellular level of ATP, which has been confirmed in the case of glucose-and phosphate limitation (Maul et al, 1995;Völker et al, 1995b). These lower levels of ATP will most probably allow an effective phosphorylation of existing or newly synthesized RsbV (S. Alper and R. Losick, personal communication), causing the enhanced formation of RsbV-RsbW complexes and the concomitant release and activation of s B .…”