Sequencing reveals similarity of the wild-type div+ gene of Bacillus subtilis to the Escherichia coli secA gene

We have determined the nucleotide (nt) sequence of the wild-type div + gene of Bacillus subtilis which complements the temperature-sensitive div-341 mutation and is involved in cell septation, sporulation, secretion of extracellular enzymes, development of competence, autolysis and spore outgrowth. It has an open reading frame encoding 841 amino acids (aa) with homology to the Escherichia coli secA gene, which is involved in protein secretion and cell separation. The deduced aa sequence of the B. subtilis div + gene shares 50% identity with that of the E. coli secA gene, and highly homologous regions were observed in the N-terminal portions. DNA-DNA hybridization with the E. coli secA gene as the probe showed that the div + gene could be easily detected by homology and that a single copy of the homologous gene was present in B. subtilis. Since both genes are similar in their functions and deduced aa sequences, we propose that the div + gene is the counterpart of the secA gene of E. coli.