In vivo expression of the Bacillus subtilis spoVE gene was studied by S1 nuclease mapping and spoVE gene fusion analysis. Transcription of spoVE is induced at about the second hour of sporulation from two closely spaced promoters designated P1 and P2. Examination of the precise transcription initiation site by high-resolution primer extension mapping indicated that the nucleotide sequences of the -10 and -35 regions of both P1 and P2 were similar to those of promoters recognized by E sigma E. Moreover, S1 nuclease mapping and translational spoVE-lacZ fusion studies with various spo mutants suggest that the expression of spoVE P2 requires the spoIIG gene product, sigma E. The sporulation of a wild-type strain was inhibited severely in the presence of a multicopy plasmid, pKBVE, carrying the spoVE promoter, indicating the possible titration of a transcriptional regulatory element(s).