The genetic basis of tetrathionate respiration in Salmonella typhimurium
The genetic basis of tetrathionate respiration in Salmonella typhimurium
复制标题
DOI：
10.1046/j.1365-2958.1999.01345.x
复制
发表时间：
1999-04-01
影响因子：
3.6
通讯作者：
Berks, BC
中科院分区：
文献类型：
--
作者：
Hensel, M;Hinsley, AP;Berks, BC
许多细菌能够使用连四硫酸盐作为末端呼吸电子受体。在此，我们报告了鼠伤寒沙门氏菌 LT2a 中连四硫酸盐呼吸所需的 ttrRSBCA 位点的鉴定和表征。 ttr 基因位于沙门氏菌致病性岛 2 的厘体 30.5 处。 ttrA、ttrB 和 ttrC 是连四硫酸盐还原酶结构基因。序列分析表明，TtrA 含有钼蝶呤鸟嘌呤二核苷酸辅因子和 [4Fe-4S] 簇，TtrB 结合四个 [4Fe-4S] 簇，TtrC 是含有对苯二酚氧化位点的整合膜蛋白。预测 TtrA 和 TtrB 通过 TtrC 锚定到细胞质膜的周质面，这意味着连四硫酸盐还原的周质位点。据推测，连四硫酸盐还原酶与硫代硫酸盐和多硫化物还原酶一起构成了以前未被识别的一类钼蝶呤依赖性酶，其进行硫-硫键的还原性裂解。 TtrA 中的 Cys-256 被认为是钼蝶呤辅因子的氨基酸配体。 TtrS 和 TtrR 是双组件调节系统的传感器和响应调节器组件，该系统是 ttrBCA 操纵子转录所必需的。活性连四硫酸盐还原系统的表达还需要缺氧响应性全局转录调节因子 Fnr。 ttrRSBCA 基因簇赋予大肠杆菌以连四硫酸盐作为电子受体进行呼吸的能力。
A range of bacteria are able to use tetrathionate as a terminal respiratory electron acceptor. Here we report the identification and characterization of the ttrRSBCA locus required for tetrathionate respiration in Salmonella typhimurium LT2a. The ttr genes are located within Salmonella pathogenicity island 2 at centisome 30.5. ttrA, ttrB and ttrC are the tetrathionate reductase structural genes. Sequence analysis suggests that TtrA contains a molybdopterin guanine dinucleotide cofactor and a [4Fe-4S] cluster, that TtrB binds four [4Fe-4S] clusters, and that TtrC is an integral membrane protein containing a quinol oxidation site. TtrA and TtrB are predicted to be anchored by TtrC to the periplasmic face of the cytoplasmic membrane implying a periplasmic site for tetrathionate reduction. It is inferred that the tetrathionate reductase, together with thiosulphate and polysulphide reductases, make up a previously unrecognized class of molybdopterin-dependent enzymes that carry out the reductive cleavage of sulphur-sulphur bonds. Cys-256 in TtrA is proposed to be the amino acid ligand to the molybdopterin cofactor. TtrS and TtrR are the sensor and response regulator components of a two-component regulatory system that is absolutely required for transcription of the ttrBCA operon. Expression of an active tetrathionate reduction system also requires the anoxia-responsive global transcriptional regulator Fnr. The ttrRSBCA gene cluster confers on Escherichia coli the ability to respire with tetrathionate as electron acceptor.