Postexponential regulation of sin operon expression in Bacillus subtilis

The expression of many gene products required during the early stages of Bacillus subtilis sporulation is regulated by sin1R operon proteins. Transcription of sin1R from the PI promoter is induced at the end of exponential growth. In vivo transcription studies suggest that PI induction is repressed by the transition-state regulatory protein Hpr and is induced by the phosphorylated form of Spo0A. In vitro DNase I footprinting studies confirmed that Hpr, AbrB, and Spo0A are trans-acting transcriptional factors that bind to the PI promoter region of sin1R. We have also determined that the P1 promoter is transcribed in vitro by the major vegetative sigma factor, sigma (A), form of RNA polymerase.