†State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, P. R. China.
‡Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, Montana 59717, United States.
Environ Sci Technol. 2015 May 19;49(10):5980-9. doi: 10.1021/es506318b. Epub 2015 May 8.
Antimony (Sb) and its compounds are listed by the United States Environmental Protection Agency (USEPA, 1979) and the European Union (CEC, 1976) as a priority pollutant. Microbial redox transformations are presumed to be an important part of antimony cycling in nature; however, regulation of these processes and the enzymology involved are unknown. In this study, comparative proteomics and reverse transcriptase-PCR analysis of Sb(III)-oxidizing bacterium Agrobacterium tumefaciens GW4 revealed an oxidoreductase (anoA) is widely distributed in microorganisms, including at least some documented to be able to oxidize Sb(III). Deletion of the anoA gene reduced Sb(III) resistance and decreased Sb(III) oxidation by ∼27%, whereas the anoA complemented strain was similar to the wild type GW4 and a GW4 anoA overexpressing strain increased Sb(III) oxidation by ∼34%. Addition of Sb(III) up-regulated anoA expression and cloning anoA to Escherichia coli demonstrated direct transferability of this activity. A His-tag purified AnoA was found to require NADP(+) as cofactor, and exhibited a K(m) for Sb(III) of 64 ± 10 μM and a V(max) of 150 ± 7 nmol min(-1) mg(-1). This study contributes important initial steps toward a mechanistic understanding of microbe-antimony interactions and enhances our understanding of how microorganisms participate in antimony biogeochemical cycling in nature.
锑（Sb）及其化合物被美国环境保护署（USEPA，1979 年）和欧盟（CEC，1976 年）列为优先污染物。微生物的氧化还原转化被认为是自然界中锑循环的重要组成部分；然而，这些过程的调控及其涉及的酶学机制尚不清楚。在这项研究中，对 Sb(III)氧化细菌根癌农杆菌 GW4 的比较蛋白质组学和逆转录 PCR 分析表明，一种氧化还原酶（anoA）广泛分布于微生物中，其中至少有一些被证明能够氧化 Sb(III)。anoA 基因的缺失降低了 Sb(III)的抗性并减少了约 27%的 Sb(III)氧化，而 anoA 互补菌株与野生型 GW4 相似，GW4 anoA 过表达菌株则增加了约 34%的 Sb(III)氧化。添加 Sb(III)可上调 anoA 的表达，将 anoA 克隆到大肠杆菌中表明该活性具有直接可转移性。发现带有 His 标签的纯化 AnoA 需要 NADP(+)作为辅助因子，其对 Sb(III)的 K(m)为 64 ± 10 μM，V(max)为 150 ± 7 nmol min(-1) mg(-1)。本研究为深入了解微生物-锑相互作用的机制提供了重要的初步步骤，并增强了我们对微生物如何参与自然界中锑生物地球化学循环的理解。
