Arsenite Oxidase Also Functions as an Antimonite Oxidase
Arsenite Oxidase Also Functions as an Antimonite Oxidase
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亚砷酸盐氧化酶也可用作锑酸盐氧化酶
DOI：
10.1128/aem.02981-14
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发表时间：
2015
影响因子：
4.4
通讯作者：
Wang, Gejiao
中科院分区：
文献类型：
--
作者：
Wang, Qian;Warelow, Thomas P.;Kang, Yoon-Suk;Romano, Christine;Osborne, Thomas H.;Lehr, Corinne R.;Bothner, Brian;McDermott, Timothy R.;Santini, Joanne M.;Wang, Gejiao
砷和锑是有毒的金属，被美国环境保护局视为优先考虑的环境污染物。在了解微生物与砷的相互作用以及它们如何影响环境中砷的氧化还原形态方面取得了重大进展。然而，即使是微生物如何以及为什么检测到锑并对其做出反应的最基本特征也仍然知之甚少。以前对根癌农杆菌菌株5A的研究得出结论，亚硫酸盐[Sb(III)]和亚砷酸盐[As(III)]的氧化需要不同的生化途径。在这里，我们在活体实验中证明，aioA[编码As(III)氧化酶的大亚基]的突变使氧化Sb(III)的能力比野生型降低了约三分之一。此外，在对纯化的根瘤菌As(III)氧化酶的体外研究中，发现从根瘤菌中分离到的As(III)氧化酶。菌株NT-26(AioA与根癌农杆菌AioA的氨基酸序列同源性为94%)提供了Sb(III)氧化的直接证据，但Vmax也显著低于As(III)的氧化。As(III)和Sb(III)均可诱导编码As(III)氧化酶的AIoBA基因表达，但Sb(III)不能诱导其表达，说明As(III)和Sb(III)的检测和转录反应不同。虽然Sb(III)和As(III)在细胞排泄(ARSB或Acr3)和与ArsR的相互作用方面相似，但它们在控制编码不同Ars或Aio活性的基因表达的调控机制上有所不同。总之，这项研究证明了微生物Sb(III)氧化的酶基础，尽管在这种细菌中也有额外的Sb(III)氧化活性。
Arsenic and antimony are toxic metalloids and are considered priority environmental pollutants by the U.S. Environmental Protection Agency. Significant advances have been made in understanding microbe-arsenic interactions and how they influence arsenic redox speciation in the environment. However, even the most basic features of how and why a microorganism detects and reacts to antimony remain poorly understood. Previous work with Agrobacterium tumefaciens strain 5A concluded that oxidation of antimonite [Sb(III)] and arsenite [As(III)] required different biochemical pathways. Here, we show within vivoexperiments that a mutation inaioA[encoding the large subunit of As(III) oxidase] reduces the ability to oxidize Sb(III) by approximately one-third relative to the ability of the wild type. Further,in vitrostudies with the purified As(III) oxidase from Rhizobium sp. strain NT-26 (AioA shares 94% amino acid sequence identity with AioA of A. tumefaciens) provide direct evidence of Sb(III) oxidation but also show a significantly decreasedVmaxcompared to that of As(III) oxidation. TheaioBAgenes encoding As(III) oxidase are induced by As(III) but not by Sb(III), whereasarsRgene expression is induced by both As(III) and Sb(III), suggesting that detection and transcriptional responses for As(III) and Sb(III) differ. While Sb(III) and As(III) are similar with respect to cellular extrusion (ArsB or Acr3) and interaction with ArsR, they differ in the regulatory mechanisms that control the expression of genes encoding the different Ars or Aio activities. In summary, this study documents an enzymatic basis for microbial Sb(III) oxidation, although additional Sb(III) oxidation activity also is apparent in this bacterium.