Grossman T H, Tuckman M, Ellestad S, Osburne M S
Department of Microbial Genetics and Biochemistry, Lederle Laboratories, American Cyanamid Company, Pearl River, New York 10965.
J Bacteriol. 1993 Oct;175(19):6203-11. doi: 10.1128/jb.175.19.6203-6211.1993.
In response to iron deprivation, Bacillus subtilis secretes a catecholic siderophore, 2,3-dihydroxybenzoyl glycine, which is similar to the precursor of the Escherichia coli siderophore enterobactin. We isolated two sets of B. subtilis DNA sequences that complemented the mutations of several E. coli siderophore-deficient (ent) mutants with defective enterobactin biosynthesis enzymes. One set contained DNA sequences that complemented only an entD mutation. The second set contained DNA sequences that complemented various combinations of entB, entE, entC, and entA mutations. The two sets of DNA sequences did not appear to overlap. AB. subtilis mutant containing an insertion in the region of the entD homolog grew much more poorly in low-iron medium and with markedly different kinetics. These data indicate that (i) at least five of the siderophore biosynthesis genes of B. subtilis can function in E. coli, (ii) the genetic organization of these siderophore genes in B. subtilis is similar to that in E. coli, and (iii) the B. subtilis entD homolog is required for efficient growth in low-iron medium. The nucleotide sequence of the B. subtilis DNA contained in plasmid pENTA22, a clone expressing the B. subtilis entD homolog, revealed the presence of at least two genes. One gene was identified as sfpo, a previously reported gene involved in the production of surfactin in B. subtilis and which is highly homologous to the E. coli entD gene. We present evidence that the E. coli entD and B. subtilis sfpo genes are interchangeable and that their products are members of a new family of proteins which function in the secretion of peptide molecules.
为应对缺铁情况，枯草芽孢杆菌分泌一种儿茶酚型铁载体，即2,3 - 二羟基苯甲酰甘氨酸，它与大肠杆菌铁载体肠杆菌素的前体相似。我们分离出两组枯草芽孢杆菌DNA序列，它们可互补几种大肠杆菌铁载体缺陷型（ent）突变体的突变，这些突变体的肠杆菌素生物合成酶存在缺陷。一组包含仅能互补entD突变的DNA序列。第二组包含能互补entB、entE、entC和entA突变的各种组合的DNA序列。这两组DNA序列似乎不重叠。在entD同源区域含有插入片段的枯草芽孢杆菌突变体在低铁培养基中生长得差得多，且动力学明显不同。这些数据表明：（i）枯草芽孢杆菌的铁载体生物合成基因中至少有五个能在大肠杆菌中发挥作用；（ii）这些铁载体基因在枯草芽孢杆菌中的遗传组织与在大肠杆菌中的相似；（iii）枯草芽孢杆菌entD同源物是在低铁培养基中高效生长所必需的。质粒pENTA22中所含的枯草芽孢杆菌DNA的核苷酸序列，该质粒是一个表达枯草芽孢杆菌entD同源物的克隆，揭示至少存在两个基因。一个基因被鉴定为sfpo，这是一个先前报道的参与枯草芽孢杆菌表面活性素产生的基因，与大肠杆菌entD基因高度同源。我们提供的证据表明，大肠杆菌entD和枯草芽孢杆菌sfpo基因是可互换的，且它们的产物是在肽分子分泌中起作用的一个新蛋白质家族的成员。
