ABacillus-Specific Factor Is Needed to Trigger the Stress-Activated Phosphatase/Kinase Cascade of ςBInduction

The Bacillus subtilis GTP Binding Protein Obg and Regulators of the ς B Stress Response Transcription Factor Cofractionate with Ribosomes

“…In E. coli, where stress induction processes are better characterized, protein denaturation and chaperone activation play key roles in communicating environmental stress to stressresponsive transcription factors (reviewed in reference 44). Although similar processes appear to control some stress-induced processes in B. subtilis, i.e., the repressor-mediated regulation of B. subtilis chaperone gene (groEL and dnaK) expression (21,22), we and others have found no obvious correlation between chaperone activity and B induction (22,28). These results argue that the mechanism that communicates environmental stress to the B induction pathway is likely to employ novel Bacillus-specific factors.…”

“…The activities of the principal chaperone proteins (DnaK and GroEL), which play important roles in stress activation in other systems, are dispensable for B induction (22,28). Additionally, the known components of the regulatory cascade that activates B are inadequate, in themselves, to detect stress and activate B (28).…”

“…The activities of the principal chaperone proteins (DnaK and GroEL), which play important roles in stress activation in other systems, are dispensable for B induction (22,28). Additionally, the known components of the regulatory cascade that activates B are inadequate, in themselves, to detect stress and activate B (28). Obg, an essential GTP binding protein of unknown function, is the only B. subtilis gene product, aside from the regulators encoded within the sigB operon, that has been shown to be needed for stress to trigger B activation (27).…”

“…Based on reconstitution studies with Escherichia coli, the Rsb proteins appear to be inadequate, in themselves, to sense stress (e.g., by changes in conformation and/or stability) and activate B (28). In E. coli, where stress induction processes are better characterized, protein denaturation and chaperone activation play key roles in communicating environmental stress to stressresponsive transcription factors (reviewed in reference 44).…”

The Growth-Promoting and Stress Response Activities of the Bacillus subtilis GTP Binding Protein Obg Are Separable by Mutation

“…Nutritional stress (e.g., glucose or phosphate limitation) generates an unknown signal to activate a separate phosphatase (RsbP/Q) that is able to dephosphorylate RsbV-P (10,28,47,51). (B) B (sigB) is coexpressed in an eight-gene operon (rsbR, rsbS, rsbT, rsbU, rsbV, rsbW, and rsbX) from a promoter (P A ) likely recognized by A -containing RNA polymerase (27,41,53). A B -dependent promoter (P B ) within the operon upregulates the distal four genes upon B activation (5, 9).…”