Expression of the sigmaB-dependent general stress regulon confers multiple stress resistance in Bacillus subtilis.
The alternative sigma factor sigmaB of Bacillus subtilis is required for the induction of approximately 100 genes after the imposition of a whole range of stresses and energy limitation. In this study, we investigated the impact of a null mutation in sigB on the stress and starvation survival of B. subtilis. sigB mutants which failed to induce the regulon following stress displayed an at least 50- to 100-fold decrease in survival of severe heat (54 degrees C) or ethanol (9%) shock, salt (10%) stress, and acid (pH 4.3) stress, as well as freezing and desiccation, compared to the wild type. Preloading cells with sigmaB-dependent general stress proteins prior to growth-inhibiting stress conferred considerable protection against heat and salt. Exhaustion of glucose or phosphate induced the sigmaB response, but surprisingly, sigmaB did not seem to be required for starvation survival. Starved wild-type cells exhibited about 10-fold greater resistance to salt stress than exponentially growing cells. The data argue that the expression of sigmaB-dependent genes provides nonsporulated B. subtilis cells with a nonspecific multiple stress resistance that may be relevant for stress survival in the natural ecosystem.
Völker
U
U
Laboratorium für Mikrobiologie und MPI für terrestrische Mikrobiologie, Philipps-Universität, 35043 Marburg, Germany.
Maul
B
B
Hecker
M
M
D000143:Acids; D000220:Adaptation, Biological / Q000235:genetics*; D001412:Bacillus subtilis / Q000187:drug effects / Q000502:physiology*; D001426:Bacterial Proteins / Q000096:biosynthesis*; D000431:Ethanol / Q000494:pharmacology; D005615:Freezing; D015964:Gene Expression Regulation, Bacterial; D018869:Heat-Shock Response; D006358:Hot Temperature; D012808:Sigma Factor / Q000096:biosynthesis*; D012965:Sodium Chloride / Q000494:pharmacology
D000143:Acids; D001426:Bacterial Proteins; C079011:SigB protein, Bacteria; D012808:Sigma Factor; D000431:Ethanol; D012965:Sodium Chloride