Bacillus subtilis spo0H gene.

A 2.8-kilobase fragment of the Bacillus subtilis chromosome containing a functional spo0H gene was cloned by using a modification of the helper system described by T. Gryczan and co-workers (T. Gryczan, S. Contente, and D. Dubnau, Mol. Gen. Genet. 177:459-467, 1980). The chromosomal segment specifically complements spo0H mutations in recE4 strains and when integrated into the chromosome of Rec+ strains maps in the spo0H region of the B. subtilis genome. A deletion within the transcribed region of the cloned spo0H gene was constructed which abolishes its spo0H+-complementing activity. DNA sequences containing this deletion were introduced into a B. subtilis Rec+ strain containing the spo0H75 mutation. The absence of recombination between the deletion and the spo0H mutation indicates that both reside in the same gene. There is homology between the B. subtilis spo0H gene and a 1.2-kilobase chromosomal fragment from Bacillus licheniformis which also complements B. subtilis spo0H mutations. In vivo transcription mapping experiments have shown that the B. subtilis spo0H gene is transcribed during vegetative growth as well as during sporulation.