Utilization of a Bacillus subtilis sigma 37 promoter by Escherichia coli RNA polymerase in vivo.

The promoter region of Bacillus subtilis subtilisin E was found to be composed of two overlapping promoters with their transcription starting sites separated from each other by 15 base pairs (Wong, S.-L., Price, C. W., Goldfarb, D. S., and Doi, R. H. (1984) Proc. Natl. Acad. Sci. U.S.A. 81, 1184-1188). At least one of the promoters is transcribed by a minor form of B. subtilis RNA polymerase with a sigma factor of 37,000 daltons. In vitro transcription analyses and in vivo studies with promoter probe plasmids pKO-1 and pCED-6 demonstrated that Escherichia coli RNA polymerase was able to initiate transcription from the subtilisin promoter cluster. S1 nuclease-mapping studies with both in vivo and in vitro transcribed RNA from E. coli and B. subtilis illustrate that E. coli can initiate transcription from both promoters with the same transcription start points as B. subtilis. The promoter strength of this promoter cluster in E. coli, as expressed in terms of galactokinase units, was 64 units and represents weak promoter activity in the E. coli system. These data indicate that either the single E. coli RNA polymerase is able to recognize the minor sigma 37 promoter or E. coli contains a hitherto unrecognized minor RNA polymerase holoenzyme which is capable of recognizing a B. subtilis sigma 37 promoter. On the other hand the B. subtilis RNA polymerase holoenzymes have been quite promoter-specific in our experiments to date.