ISOLATION AND CHARACTERIZATION OF BACILLUS-SUBTILIS GENES INVOLVED INSIDEROPHORE BIOSYNTHESIS - RELATIONSHIP BETWEEN BACILLUS-SUBTILIS SFP(0) AND ESCHERICHIA-COLI ENTD GENES

In response to iron deprivation, Bacillus subtilis secretes a catechol ic siderophore, 2,3-dihydroxybenzoyl glycine, which is similar to the precursor of the Escherichia coli siderophore enterobactin. We isolate d two sets of B. subtilis DNA sequences that complemented the mutation s of several E. coli siderophore-deficient (ent) mutants with defectiv e enterobactin biosynthesis enzymes. One set contained DNA sequences t hat complemented only an entD mutation. The second set contained DNA s equences that complemented various combinations of entB, entE, entC, a nd entA mutations. The two sets of DNA sequences did not appear to ove rlap. A B. subtilis mutant containing an insertion in the region of th e entD homolog grew much more poorly in low-iron medium and with marke dly different kinetics. These data indicate that (i) at least five of the siderophore biosynthesis genes of B. subtilis can function in E. c oli, (ii) the genetic organization of these siderophore genes in B. su btilis is similar to that in E. coli, and (iii) the B. subtilis entD h omolog is required for efficient growth in low-iron medium. The nucleo tide sequence of the B. subtilis DNA contained in plasmid pENTA22, a c lone expressing the B. subtilis entD homolog, revealed the presence of at least two genes. One gene was identified as sfp0, a previously rep orted gene involved in the production of surfactin in B. subtilis and which is highly homologous to the E. coli entD gene. We present eviden ce that the E. coli entD and B. subtilis sfp0 genes are interchangeabl e and that their products are members of a new family of proteins whic h function in the secretion of peptide molecules.