Signal transduction and sporulation in Bacillus subtilis: autophosphorylation of Spo0A, a sporulation initiation gene product.

Spo0A is a positive/negative transcriptional regulator that plays a very important role in sporulation initiation in Bacillus subtilis. The N-terminal amino acid sequence of Spo0A is homologous to that of regulator proteins of the two-component regulatory systems involved in signal transduction in bacteria. Phosphorylation of SpooA through a phosphorelay has been reported recently. In this study, we found that Spo0A is autophosphorylated in the presence of ATP and that an autophosphorylation-deficient Spo0A mutant is completely defective in initiating sporulation. These results suggest that Spo0A autophosphorylation is an essential event in the signal transduction process that controls sporulation in B. subtilis.