NemA Catalyzes Trivalent Organoarsenical Oxidation and Is Regulated by the Trivalent Organoarsenical-Selective Transcriptional Repressor NemR.
NemA Catalyzes Trivalent Organoarsenical Oxidation and Is Regulated by the Trivalent Organoarsenical-Selective Transcriptional Repressor NemR.
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NemA 催化三价有机砷氧化，并受三价有机砷选择性转录阻遏蛋白 NemR 调节
DOI：
10.1021/acs.est.1c00574
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发表时间：
2021-05-04
影响因子：
11.4
通讯作者：
Wang G
中科院分区：
文献类型：
--
作者：
Shi K;Radhakrishnan M;Dai X;Rosen BP;Wang G
合成的芳香族化合物，如洛克沙宗(ROX(V))和硝胺酮(NIT(V))已被用作动物生长促进剂和除草剂。微生物有助于在毒性相对较低的五价和剧毒的三价军火库之间进行氧化还原循环。在本研究中，我们报道了从肠杆菌属中鉴定出Nemra操纵子。Z1，表明它参与了三价有机砷的氧化。铬(VI)、Rox(III)和Nit(III)诱导NEMA的表达。NEMA在大肠杆菌中的异源表达使其对铬(VI)、亚甲基亚硝酸盐(Mas(III))、Rox(III)和Nit(III)产生抗性。纯化的NEMA能同时催化Cr(VI)还原和Mas(III)/Rox(III)/NiT(III)氧化，且在Cr(VI)存在下氧化作用增强。电泳迁移率改变分析和荧光分析的结果表明，转录抑制物NemR与Rox(III)或Nit(III)结合。NEMR有三个保守的半胱氨酸残基，分别是Cys21、Cys106和Cys116。三者中的任何一个突变都会导致对Rox(III)/Nit(III)的反应丧失，表明它们形成了Rox(III)/Nit(III)结合位点。这些结果表明，NEMA是一种新的三价有机砷氧化酶，受三价有机砷选择性抑制物NEMR的调控。这一发现拓展了我们对有机砷氧化分子机理的认识，为研究环境有毒化合物的氧化还原偶联作用提供了基础。
Synthetic aromatic arsenicals such as roxarsone (Rox(V)) and nitarsone (Nit(V)) have been used as animal growth enhancers and herbicides. Microbes contribute to redox cycling between the relatively less toxic pentavalent and highly toxic trivalent arsenicals. In this study, we report the identification of nemRA operon from Enterobacter sp. Z1 and show that it is involved in trivalent organoarsenical oxidation. Expression of nemA is induced by chromate (Cr(VI)), Rox(III), and Nit(III). Heterologous expression of NemA in Escherichia coli confers resistance to Cr(VI), methylarsenite (MAs(III)), Rox(III), and Nit(III). Purified NemA catalyzes simultaneous Cr(VI) reduction and MAs(III)/Rox(III)/Nit(III) oxidation, and oxidation was enhanced in the presence of Cr(VI). The results of electrophoretic mobility shift assays and fluorescence assays demonstrate that the transcriptional repressor, NemR, binds to either Rox(III) or Nit(III). NemR has three conserved cysteine residues, Cys21, Cys106, and Cys116. Mutation of any of the three resulted in loss of response to Rox(III)/Nit(III), indicating that they form an Rox(III)/Nit(III) binding site. These results show that NemA is a novel trivalent organoarsenical oxidase that is regulated by the trivalent organoarsenical-selective repressor NemR. This discovery expands our knowledge of the molecular mechanisms of organoarsenical oxidation and provides a basis for studying the redox coupling of environmental toxic compounds.
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DOI：
10.1107/s0907444904019158
发表时间：
2004-12-01
影响因子：
2.2
作者：
Emsley, P;Cowtan, K
通讯作者：
Cowtan, K
DOI：
10.1073/pnas.2001063117
发表时间：
2020-05-12
影响因子：
11.1
作者：
Chen, Song-Can;Sun, Guo-Xin;Zhu, Yong-Guan
通讯作者：
Zhu, Yong-Guan
影响因子：
3
作者：
Nyantakyi, A. J.;Akoto, O.;Fei-Baffoe, B.
通讯作者：
Fei-Baffoe, B.
DOI：
10.1093/bioinformatics/btq662
发表时间：
2011-02-01
期刊：
Bioinformatics (Oxford, England)
影响因子：
--
作者：
Benkert P;Biasini M;Schwede T
通讯作者：
Schwede T
DOI：
10.1016/j.scitotenv.2020.141339
发表时间：
2020-12-15
期刊：
The Science of the total environment
影响因子：
--
作者：
Chen J;Rosen BP
通讯作者：
Rosen BP