New RNA polymerase sigma factor under spo0 control in Bacillus subtilis.

In Bacillus subtilis transcription of spoVG is activated within minutes after the initiation of sporulation. Mutations in several spo0 genes prevent the activation of spoVG transcription. We have found a sigma-like protein that is capable of directing core RNA polymerase to use the spoVG promoter in an in vitro run-off transcription assay. This sigma-like protein was not found to be associated with RNA polymerase in a spo0A or spo0B mutant but was present in a spo0H mutant. We suggest that one role of the spo0A gene product in transcription of spoVG is the modulation of RNA polymerase activity by this sigma-like protein.