The Bacillus subtilis dnaC gene encodes a protein homologous to the DnaB helicase of Escherichia coli.

Within the region of the Bacillus subtilis chromosome assigned to us in the genome sequencing project, we found a gene, the product of which is similar to the DnaB protein (replicative DNA helicase) of Escherichia coli. Three B. subtilis dna gene mutations, dnaC30 and ts56 causing defects in elongation and ts199 causing a defect in the initiation of replication, were mapped in the gene by transformation and DNA sequencing. Both dnaC30 and ts56 have been located near the amino-terminal end of the B. subtilis DnaC protein. In contrast, ts199 has been located near the carboxy-terminal of the protein. Our results indicate that the B. subtilis dnaC gene encodes a counterpart of the E. coli dnaB helicase.