title: Arsenic Methyltransferase is Involved in Arsenosugar Biosynthesis by Providing DMA.
abstract: Arsenic is an ubiquitous toxic element in the environment, and organisms have evolved different arsenic detoxification strategies. Studies on arsenic biotransformation mechanisms have mainly focused on arsenate (As(V)) reduction, arsenite (As(III)) oxidation, and arsenic methylation; little is known, however, about the pathway for the biosynthesis of arsenosugars, which are significant arsenic transformation products. Here, the involvement of As(III) S-Adenosylmethionine methyltransferase (ArsM) in arsenosugar synthesis is demonstrated for the first time. Synechocystis sp. PCC 6803 incubated with As(III) or monomethylarsonic acid (MMA(V)) produced dimethylarsinic acid (DMA(V)) and arsenosugars, as determined by high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC/ICPMS). Arsenosugars were also detected in the cells when they were exposed to DMA(V). A mutant strain Synechocystis ΔarsM was constructed by disrupting arsM in Synechocystis sp. PCC 6803. Methylation of arsenic species was not observed in the mutant strain after exposure to arsenite or MMA(V); when Synechocystis ΔarsM was incubated with DMA(V), arsenosugars were detected in the cells. These results suggest that ArsM is a required enzyme for the methylation of inorganic arsenicals, but not required for the synthesis of arsenosugars from DMA, and that DMA is the precursor of arsenosugar biosynthesis. The findings will stimulate more studies on the biosynthesis of complex organoarsenicals, and lead to a better understanding of the bioavailability and function of the organoarsenicals in biological systems.
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences , Xiamen 361021, China.
authors.forename: Xi-Mei
authors.initials: XM
authors.lastname: Xue
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: Institute of Chemistry, University of Graz , Graz, Austria.
authors.forename: Georg
authors.initials: G
authors.lastname: Raber
authors.affiliation: Institute of Chemistry, University of Graz , Graz, Austria.
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Francesconi
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences , Xiamen 361021, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences , Wuhan, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Gao
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences , Xiamen 361021, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Yan
authors.affiliation: College of Resources and Environment, Fujian Agriculture and Forestry University , Fuzhou, China.
authors.forename: Christopher
authors.initials: C
authors.lastname: Rensing
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences , Xiamen 361021, China.|State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing, China.
authors.forename: Yong-Guan
authors.identifier: 0000-0003-3861-8482
authors.initials: YG
authors.lastname: Zhu
mesh_terms: D001151:Arsenic / Q000378:metabolism*; D001152:Arsenicals / Q000378:metabolism; D002101:Cacodylic Acid / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D013058:Mass Spectrometry; D008780:Methyltransferases; D012436:S-Adenosylmethionine
chemical_list: D001152:Arsenicals; D012436:S-Adenosylmethionine; D002101:Cacodylic Acid; D008780:Methyltransferases; D001151:Arsenic