Rowland B M, Grossman T H, Osburne M S, Taber H W
Department of Microbiology, Immunology and Molecular Genetics, Albany Medical College, NY 12208, USA.
Gene. 1996 Oct 31;178(1-2):119-23. doi: 10.1016/0378-1119(96)00349-6.
Under iron-limiting conditions, Bacillus subtilis (Bs) produces the siderophore 2,3-dihydroxybenzoate (DHB) to acquire extracellular iron. In Escherichia coli (Ec), DHB is a precursor of the siderophore enterobactin, which suggested that Bs may possess similar biosynthetic enzymes. The sequences of two overlapping Bs clones capable of complementing Ec enterobactin mutants [Grossman, T.H., Tuckman, M., Ellestad, S. and Osburne, M.S. (1993) Isolation and characterization of Bacillus subtilis genes involved in siderophore biosynthesis: Relationship between B. subtilis sfpo and Escherichia coli entD genes. J. Bacteriol. 175, 6203-6211] were analyzed and five open reading frames were identified. These genes are located near 291 degrees on the Bs chromosome and have been termed dhbA, dhbC, dhbE, dhbB and dhbF, based on similarities to Ec ent homologs. Amino-acid identities between gene product homologs are: EntA and DhbA, 41%; EntC and DhbC, 35%; EntE and DhbE, 48%; EntB and DhbB, 54%; and EntF and DhbF, 29%. DhbC is also 35% identical to the Bs menaquinone-specific isochorismate synthase, MenF, illustrating an example of gene duplication. Operon disruption studies suggested that the dhb genes comprise an operon of at least four genes.
在铁限制条件下，枯草芽孢杆菌（Bs）会产生铁载体2,3 - 二羟基苯甲酸（DHB）以获取细胞外铁。在大肠杆菌（Ec）中，DHB是铁载体肠杆菌素的前体，这表明Bs可能拥有类似的生物合成酶。对两个能够互补Ec肠杆菌素突变体的Bs重叠克隆的序列[格罗斯曼，T.H.，塔克曼，M.，埃尔斯塔德，S.和奥斯本，M.S.（1993年）参与铁载体生物合成的枯草芽孢杆菌基因的分离与表征：枯草芽孢杆菌sfpo与大肠杆菌entD基因之间的关系。《细菌学杂志》175，6203 - 6211]进行了分析，并鉴定出五个开放阅读框。这些基因位于Bs染色体上约291度的位置，基于与Ec ent同源物的相似性，已被命名为dhbA、dhbC、dhbE、dhbB和dhbF。基因产物同源物之间的氨基酸同一性为：EntA和DhbA，41%；EntC和DhbC，35%；EntE和DhbE，48%；EntB和DhbB，54%；EntF和DhbF，29%。DhbC与Bs甲萘醌特异性异分支酸合酶MenF也有35%的同一性，这说明了基因重复的一个例子。操纵子破坏研究表明，dhb基因组成了一个至少包含四个基因的操纵子。
