Stress Triggers a Process That Limits Activation of the <i>Bacillus subtilis</i> Stress Transcription Factor ς ^B

Abstract

Stress-induced activation of the Bacillus subtilis transcription factor sigma(B) is transitory. To determine whether the process that limits sigma(B) activation 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 monitored for the persistence of sigma(B) activity. Without ethanol treatment, the induced cultures displayed continuously high sigma(B) activity. Ethanol treatment restricted ongoing sigma(B) activity, but only in strains with intact rsbX and -S genes. The loss of other gene products (RsbR and Obg) known to participate in the stress activation pathway had little influence in blocking the ethanol effect. The data argue that stress upregulates the activity of the RsbX-S regulatory pair to restrict sigma(B) induction following stress.