The chromosomal arsenic resistance genes of Thiobacillus ferrooxidans have an unusual arrangement and confer increased arsenic and antimony resistance to Escherichia coli
The chromosomal arsenic resistance genes of Thiobacillus ferrooxidans have an unusual arrangement and confer increased arsenic and antimony resistance to Escherichia coli
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DOI：
10.1128/aem.66.5.1826-1833.2000
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发表时间：
2000-05-01
影响因子：
4.4
通讯作者：
Rawlings, DE
中科院分区：
文献类型：
--
作者：
Butcher, BG;Deane, SM;Rawlings, DE
对嗜酸性、化石型自养、生态型氧化亚铁硫杆菌的染色体抗砷基因进行了克隆和测序。鉴定了四个抗砷基因arsb、arsC、arsh和一个可能的arsR基因的同源基因。将氧化亚铁硫杆菌arsb(亚砷酸盐输出)和arsC(亚砷酸盐还原酶)基因产物克隆到大肠杆菌ars缺失突变体中，并增强了它们对亚砷酸盐、砷酸盐和锑的抗性。因此，尽管ars基因来自一种嗜酸性细菌，但它们在大肠杆菌中是起作用的。虽然氧化亚铁硫杆菌是革兰氏阴性菌，但其ArsC与革兰氏阳性菌的ArsC分子关系更密切。此外，在大肠杆菌中，ArsC介导的砷酸盐抗性需要一个功能性的trxA(硫氧还蛋白)基因；这一发现证实了这种抗性的革兰氏阳性ArsC样状态，并表明基于Gram染色结果的ArsC分子的划分是人为的。虽然Arsh在大肠杆菌的体外转录-翻译系统中得到了表达，但Arsh不是大肠杆菌抗砷所必需的，也不能增强大肠杆菌的抗砷能力。氧化亚铁链霉菌ars基因的排列异常，可能的arsR、arsC基因和arsBH基因的翻译方向相反，这一差异取向在所研究的4株铁氧化葡萄球菌中是保守的。
The chromosomal arsenic resistance genes of the acidophilic, chemolithoautotrophic, biomining bacterium Thiobacillus ferrooxidans were cloned and sequenced. Homologues of four arsenic resistance genes, arsB, arsC, arsH, and a putative arsR gene, were identified. The T. ferrooxidans arsB (arsenite export) and arsC (arsenate reductase) gene products were functional when they were cloned in an Escherichia coli ars deletion mutant and conferred increased resistance to arsenite, arsenate, and antimony. Therefore, despite the fact that the ars genes originated from an obligately acidophilic bacterium, they were functional in E. coli. Although T. ferrooxidans is gram negative, its ArsC was more closely related to the ArsC molecules of gram-positive bacteria. Furthermore, a functional trxA (thioredoxin) gene was required for ArsC-mediated arsenate resistance in E. coli; this finding confirmed the gram-positive ArsC-like status of this resistance and indicated that the division of ArsC molecules based on Gram staining results is artificial. Although arsH was expressed in an E. coli-derived in vitro transcription-translation system, ArsH was not required for and did not enhance arsenic resistance in E. coli. The T. ferrooxidans ars genes mere arranged in an unusual manner, and the putative arsR and arsC genes and the arsBH genes were translated in opposite directions, This divergent orientation was conserved in the four T. ferrooxidans strains investigated.