Stress triggers a process that limits activation of the Bacillus subtilis stress transcription factor sigma(B)

Stress-induced activation of the Bacillus subtilis transcription factor sig ma(B) is transitory. To determine whether the process that limits ap activa tion is itself triggered by stress, B. subtilis strains in which the stress pathway was artificially activated by the induced expression of a positive regulatory protein (RsbT) were exposed to ethanol stress and were monitore d for the persistence of sigma(B) activity. Without ethanol treatment, the induced cultures displayed continuously high sigma(B) activity. Ethanol tre atment restricted ongoing sigma(B) activity, but only in strains with intac t rsbX and -S genes. The loss of other gene products (RsbR and Obg) known t o participate in the stress activation pathway had little influence in bloc king the ethanol effect. The data argue that stress upregulates the activit y of the RsbX-S regulatory pair to restrict sigma(B) induction following st ress.