THE DACF-SPOIIA OPERON OF BACILLUS-SUBTILIS, ENCODING SIGMA(F), IS AUTOREGULATED

The spoIIA operon of Bacillus subtilis encodes sigma(F) and two proteins that may regulate sigma factor activity. High level induction of the tricistronic spoIIA operon occurs early during spore formation. At later times, the locus is cotranscribed with the upstream gene dacF, which encodes a putative DD-carboxypeptidase, In this study, the regulation of dacF-spoIIA transcription has been analyzed. Expression of a dacF-lacZ transcriptional fusion during sporulation required sigma(F) but not the later-expressed sporulation-associated sigma factors. Induction of sigma(F) synthesis during vegetative growth caused expression of dacF-lacZ fusions. The dacF-spoIIA promoter sequence is similar to sequences of previously identified sigma(F) promoters. It is concluded that dacF-spoIIA is transcribed by E sigma(F). We present evidence that dacF-spoIIA is also transcribed by E sigma(G), as is the case for the three other promoters known to be transcribed by E sigma(F).