Alami N, Hallenbeck P C
Département de microbiologie et immunologie, Université de Montréal, Québec, Canada.
Gene. 1995 Apr 14;156(1):53-7. doi: 10.1016/0378-1119(94)00930-q.
We cloned, by complementation of an H2S- mutant, a cluster of Salmonella typhimurium genes, phsBCDEF, that appears to be essential for the anaerobic production of hydrogen sulfide from thiosulfate. Tn5 mutagenesis and ExoIII deletion analysis showed that approx. the entire region of a 3.3-kb subclone was necessary for H2S production. Subsequent sequencing revealed the presence of five potential translationally coupled open reading frames (ORFs). Their putative protein products were confirmed by synthesis from a phage T7 expression system. Comparison of the encoded sequences with previously determined sequences suggests that these genes constitute part of a thiosulfate-reducing operon coding for a membrane-associated electron transport chain which contains proteins potentially capable of ligating iron-sulfur clusters and heme. Immediately upstream from these genes, a region encoding the C-terminal portion of an ORF (OrfA) was identified that showed a high degree of similarity to some other anaerobic terminal reductases, polysulfide reductase (PsrA) of Wolinella succinogenes and dimethylsulfoxide reductase (DmsA), formate dehydrogenase (formate-hydrogene-lyase linked) (FdhF) and nitrate reductase (NarG) of Escherichia coli.
我们通过对一个硫化氢突变体进行互补克隆，得到了鼠伤寒沙门氏菌的一组基因phsBCDEF，这些基因似乎对于从硫代硫酸盐厌氧产生硫化氢至关重要。Tn5诱变和ExoIII缺失分析表明，约3.3 kb亚克隆的整个区域对于硫化氢的产生都是必需的。随后的测序揭示了五个潜在的翻译偶联开放阅读框（ORF）的存在。通过噬菌体T7表达系统的合成证实了它们推定的蛋白质产物。将编码序列与先前确定的序列进行比较表明，这些基因构成了一个硫代硫酸盐还原操纵子的一部分，该操纵子编码一个与膜相关的电子传递链，其中包含可能能够连接铁硫簇和血红素的蛋白质。在这些基因的紧邻上游，鉴定出一个编码ORF（OrfA）C末端部分的区域，该区域与其他一些厌氧末端还原酶具有高度相似性，即琥珀酸沃林氏菌的多硫化物还原酶（PsrA）和二甲基亚砜还原酶（DmsA）、大肠杆菌的甲酸脱氢酶（与甲酸-氢裂解酶相连）（FdhF）和硝酸盐还原酶（NarG）。
