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

The spoIIA operon of Bacillus subtilis encodes sigma(F) and two protei ns that may regulate sigma factor activity. High level induction of th e tricistronic spoIIA operon occurs early during spore formation. At l ater times, the locus is cotranscribed with the upstream gene dacF, wh ich encodes a putative DD-carboxypeptidase, In this study, the regulat ion of dacF-spoIIA transcription has been analyzed. Expression of a da cF-lacZ transcriptional fusion during sporulation required sigma(F) bu t not the later-expressed sporulation-associated sigma factors. Induct ion of sigma(F) synthesis during vegetative growth caused expression o f dacF-lacZ fusions. The dacF-spoIIA promoter sequence is similar to s equences of previously identified sigma(F) promoters. It is concluded that dacF-spoIIA is transcribed by E sigma(F). We present evidence tha t dacF-spoIIA is also transcribed by E sigma(G), as is the case for th e three other promoters known to be transcribed by E sigma(F).