Characterization of spoIVA, a sporulation gene involved in coat morphogenesis in Bacillus subtilis.

We report the cloning and characterization of the Bacillus subtilis sporulation locus spoIVA, mutations at which cause an unusual defect in spore formation in which the coat misassembles as swirls within the mother cell. We show that spoIVA is a single gene of 492 codons that is capable of encoding a polypeptide of 55 kDa. Transcription of spoIVA is induced at about the second hour of sporulation by the regulatory protein sigma E from two closely spaced promoters designated P1 and P2. Experiments in which the upstream promoter P1 was removed show that transcription of spoIVA from P2 is sufficient for efficient spore formation. Based on these and other findings, we infer that the spoIVA gene product is a morphogenetic protein; we discuss its role in the deposition of coat polypeptides around the developing forespore.