Bacillus subtilis subtilisin gene (aprE) is expressed from a sigma A (sigma 43) promoter in vitro and in vivo.

In vitro studies demonstrated that the Bacillus subtilis subtilisin gene (aprE) could be transcribed by RNA polymerase holoenzyme reconstituted from core and sigma A factor obtained from vegetative cells. Upstream deletions (from -45) reduced the amount of transcription from the promoter. A deletion downstream of the promoter that overlapped a putative downstream minor promoter did not affect transcription from the sigma A promoter, which indicated that the putative downstream promoter is not utilized in vivo. S1 nuclease mapping studies showed that there was a low level of transcription from the subtilisin promoter during the growth phase and that the site of transcription initiation was the same during log and stationary phases. We conclude from these findings that there is only one promoter for the subtilisin gene and that it can be transcribed by the sigma A form of RNA polymerase in vitro.