title: Identification and characterization of the arsenite methyltransferase from a protozoan, Tetrahymena pyriformis.
abstract: Arsenic (As) methylation in aquatic microbes plays a major role in the biogeochemistry of As. Protozoa, especially the free-living freshwater species, are important players in aquatic ecological health. In this study, an arsenite (As(III)) methyltransferase, TpyArsM, was identified and characterized in a free-living protozoan, Tetrahymena pyriformis. In order to confirm its function, TpyarsM gene was knocked-out in Tetrahymena and was also heterologously expressed in hypersensitive E. coli; these events resulted in expected decreases in As tolerance and methylation ability, respectively. In-vitro tests revealed that purified TpyArsM protein methylated inorganic As to mono- and di- methylarsenate, and also had the novel property of producing trimethylarsenite (TMA(III)) and dimethylarsine (Me2AsH) gases. This new methyltransferase gene, identified in a species near the base of the food web, has enriched our knowledge of As methyltransferases and has great potential for bioremediation of As-contaminated environments.
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Ye
authors.affiliation: Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Chang
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Yan
authors.affiliation: Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Xiong
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Xi-Mei
authors.initials: XM
authors.lastname: Xue
authors.affiliation: Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
authors.forename: Dongxia
authors.initials: D
authors.lastname: Yuan
authors.affiliation: State Key Lab of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Guo-Xin
authors.initials: GX
authors.lastname: Sun
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; State Key Lab of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. Electronic address: ygzhu@iue.ac.cn.
authors.forename: Yong-Guan
authors.initials: YG
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China. Electronic address: miaowei@ihb.ac.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Miao
mesh_terms: D001151:Arsenic / Q000737:chemistry / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D055786:Gene Knockout Techniques; D020128:Inhibitory Concentration 50; D008745:Methylation; D008780:Methyltransferases / Q000235:genetics* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013769:Tetrahymena pyriformis / Q000201:enzymology* / Q000235:genetics*; D014835:Volatilization
chemical_list: D011994:Recombinant Proteins; D008780:Methyltransferases; C116338:arsenite methyltransferase; D001151:Arsenic
keywords: Arsenic; Heavy metal; Methylarsine; Methyltransferase; Protozoan; Tetrahymena pyriformis