A Bacillus-specific factor is needed to trigger the stress-activated phosphatase/kinase cascade of sigma(B) induction

The general stress regulon of Bacillus subtilis is controlled by the transc ription factor sigma(B). Environmental stress activates sigma(B) via a phos phatase/kinase cascade that triggers sigma(B,)s release from an anti sigma factor complex. To determine if the members of the; phosphatase/kinase casc ade are sufficient to detect environmental stress and activate sigma(B), we expressed sigma(B) and its regulators in E. coli, In E, coli, as in B. sub tilis, the intact collection of regulators silenced sigma(B), while allowin g sigma(B) to be active if the cascade's most upstream negative regulator w as deleted. The regulators could not, however, activate sigma(B) in respons e to ethanol treatment or heat shock. In other experiments, the GroEL and D naK chaperones, known to be important in controlling stress sigma factors i n E. coli, were found to be unimportant for sigma(B) activity in B, subtili s. The findings argue that stress induction of sigma(B) requires novel fact ors that are B. subtilis specific, (C) 1999 Academic Press.