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. coil; 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. (C) 2014 Elsevier B.V. All rights reserved.
英文摘要:
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. (C) 2014 Elsevier B.V. All rights reserved.
1.Chinese Acad Sci, Inst Urban Environm, Key Lab Urban Environm & Hlth, Xiamen 361021, Peoples R China 2.Chinese Acad Sci, Inst Hydrobiol, Key Lab Aquat Biodivers & Conservat, Wuhan 430072, Peoples R China 3.Univ Chinese Acad Sci, Beijing 100049, Peoples R China 4.Chinese Acad Sci, Ecoenvironm Sci Res Ctr, State Key Lab Urban & Reg Ecol, Beijing 100085, Peoples R China
Recommended Citation:
Ye, Jun; Chang, Yue; Yan, Yu; Xiong, Jie; Xue, Xi-Mei; Yuan, Dongxia; Sun, Guo-Xin; Zhu, Yong-Guan; Miao, Wei.Identification and characterization of the arsenite methyltransferase from a protozoan, Tetrahyrnena pyriformis,AQUATIC TOXICOLOGY,2014,149():50-57
