Widespread Distribution of the arsO Gene Confers Bacterial Resistance to Environmental Antimony.
Widespread Distribution of the arsO Gene Confers Bacterial Resistance to Environmental Antimony.
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DOI：
10.1021/acs.est.3c03458
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发表时间：
2023-09
影响因子：
11.4
通讯作者：
Shi Tang;Xin-Wei Song;Jian Chen;Jie Shen;Bin Ma;Barry P. Rosen;Jun Zhang;Fangjie Zhao
中科院分区：
文献类型：
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作者：
Shi Tang;Xin-Wei Song;Jian Chen;Jie Shen;Bin Ma;Barry P. Rosen;Jun Zhang;Fangjie Zhao
微生物氧化环境中的锑（Sb（III））生成锑酸盐（Sb（V））是锑（Sb）的解毒机制。从受Sb污染的水稻土中分离的细菌Ensifer adhaerens ST 2在好氧条件下将Sb（III）氧化为Sb（V），其氧化机理尚不清楚。ST 2的基因组分析揭示了一个未知功能的基因在抗砷（ars）操纵子，我们术语arsO。通过添加Sb（III），arsO的转录水平显著上调。ArsO被预测为黄素蛋白单加氧酶，但与其他黄素蛋白单加氧酶的序列相似性较低。在对砷过敏的大肠杆菌菌株AW 3110 Δars中表达arsO可增强对Sb（III）的抗性，但对亚砷酸盐（As（III））或甲基砷（MAs（III））的抗性没有增强。纯化的ArsO催化Sb（III）氧化成Sb（V），NADPH或NADH作为电子供体，但不氧化As（III）或MAs（III）。纯化的酶含有黄素腺嘌呤二核苷酸（FAD）的比例为0.62摩尔的FAD/摩尔蛋白质，并通过添加FAD的酶活性增加。生物信息学分析表明，arsO基因广泛分布于不同环境的宏基因组中，在受人类活动影响的环境中尤为丰富。这项研究表明，ArsO是一种环境Sb（III）氧化酶，在Sb（III）的解毒中起着重要的作用。
Microbial oxidation of environmental antimonite (Sb(III)) to antimonate (Sb(V)) is an antimony (Sb) detoxification mechanism. Ensifer adhaerens ST2, a bacterial isolate from a Sb-contaminated paddy soil, oxidizes Sb(III) to Sb(V) under oxic conditions by an unknown mechanism. Genomic analysis of ST2 reveals a gene of unknown function in an arsenic resistance (ars) operon that we term arsO. The transcription level of arsO was significantly upregulated by the addition of Sb(III). ArsO is predicted to be a flavoprotein monooxygenase but shows low sequence similarity to other flavoprotein monooxygenases. Expression of arsO in the arsenic-hypersensitive Escherichia coli strain AW3110Δars conferred increased resistance to Sb(III) but not arsenite (As(III)) or methylarsenite (MAs(III)). Purified ArsO catalyzes Sb(III) oxidation to Sb(V) with NADPH or NADH as the electron donor but does not oxidize As(III) or MAs(III). The purified enzyme contains flavin adenine dinucleotide (FAD) at a ratio of 0.62 mol of FAD/mol protein, and enzymatic activity was increased by addition of FAD. Bioinformatic analyses show that arsO genes are widely distributed in metagenomes from different environments and are particularly abundant in environments affected by human activities. This study demonstrates that ArsO is an environmental Sb(III) oxidase that plays a significant role in the detoxification of Sb(III).