In vivo effects of sporulation kinases on mutant Spo0A proteins in Bacillus subtilis

The phosphorylated form of the response regulator Spo0A (Spo0A similar toP) is required for the initiation of sporulation in Bacillus subtilis. Phosph ate is transferred to Spo0A from at least four histidine kinases (KinA, Kin B, KinC, and KinD) by a phosphotransfer pathway composed of Spo0F and Spo0B . Several mutations in spo0A allow initiation of sporulation in the absence of spo0F and spo0B, but the mechanisms by which these mutations allow bypa ss of spo0F and spo0B are not fully understood. We measured the ability of KinA, Mull, and KinC to activate sporulation of five spo0A mutants in the a bsence of Spo0F and Spo0B. We also determined the effect of Spo0E, a Spo0A similar toP-specific phosphatase, on sporulation of strains containing the spo0A mutations. Our results indicate that several of the mutations relax t he specificity of Spo0A allowing Spo0A to obtain phosphate from a broader g roup of phosphodonors. In the course of these experiments, we observed medi um-dependent effects on the sporulation of different mutants. This led us t o identify a small molecule, acetoin, that can stimulate sporulation of som e spo0A mutants.