Involvement of acetyl phosphate in the in vivo activation of the response regulator ComA in Bacillus subtilis.

Development of genetic competence in Bacillus subtilis is regulated by ComP--ComA, a two-component signal transduction system. The response regulator ComA is primarily activated by ComP, a histidine kinase that mediates response to nutrient conditions and cell density, and the activated ComA is required for transcription of the srf operon, which is essential for the development of genetic competence and surfactin production. In this study we suggested that the ComA could also be activated by a small molecule phospho-donor, acetyl phosphate. Examination of srfA-lacZ expression indicated that a significant amount of srfA expression still occurs in the comP mutant during growth in a sporulation medium containing excess glucose. Analysis of a comP and pta mutant suggests that srfA activation seen in the comP mutant is dependent on the expression of pta, which encodes phosphotransacetylase (Pta). As Pta is responsible for the catalysis for conversion of acetyl coenzyme A to acetyl phosphate, we conclude that the expression of srfA seen in the comP mutant is mainly due to the activation of ComA by acetyl phosphate.