TRANSCRIPTIONAL CONTROL OF THE BACILLUS-SUBTILIS SPOIID GENE

We cloned the wild-type allele of the spoIID locus of Bacillus subtilis. This DNA region was shown to be transcribed beginning within an hour after the onset of sporulation. The amount of spoIID mRNA present in cells at 1 h after the end of growth was more than 50-fold greater than it was in growing cells; the pool of this mRNA decreased steadily after 1.5 h after the end of growth. spoIID mRNA was present in stationary-phase cells of sporulation mutants with lesions in the spo0J and spoIIB genes but was absent in cells carrying spo0B, spo0H, spoIIA, spoIIE, spoIIG, or spoIIIA mutations. In vitro runoff transcription with the E.sigma.55, E.sigma.37, E.sigma.32, and E.sigma.29 forms of RNA polymerase indicated that only the E.sigma.29 form was able to transcribe the spoIID gene. This result is consistent with results of studies with the Spo- mutants, because only mutants that produced E.sigma.29 were able to produce spoIID mRNA in vivo. In the course of this work, two additional transcription units were discovered in the DNA region neighboring the spoIID gene. One of these was expressed during vegetative growth; the other was expressed early during sporulation and corresponded to an in vitro transcript produced by the E.sigma.29 form of RNA polymerase.