title: A novel amidohydrolase (DmhA) from Sphingomonas sp. that can hydrolyze the organophosphorus pesticide dimethoate to dimethoate carboxylic acid and methylamine.
abstract: OBJECTIVE
  To characterize a novel dimethoate amidohydrolase from Sphingomonas sp. DC-6.
  
  
  RESULTS
  A gene, dmhA, encoding the dimethoate amidohydrolase responsible for transforming dimethoate to dimethoate carboxylic acid and methylamine, was cloned from Sphingomonas sp. DC-6. Sequence analysis and molecular modeling indicate that DmhA shares 31-57 % amino acid sequence identities with other functionally confirmed amidohydrolase. DmhA was expressed in Escherichia coli BL21 (DE3) and purified by Ni-NTA affinity chromatography. The purified DmhA could hydrolyze 4-acetaminophenol, dimethoate and propanil. DmhA activity was optimal at 30 °C and pH 7.5. Hg(2+), Zn(2+), Cu(2+), Cd(2+), Tween 80, Triton X-100 or SDS strongly inhibited its activity. The K m and k cat values of DmhA for dimethoate are 0.02 mM and 1.2 s(-1), respectively.
  
  
  CONCLUSIONS
  DmhA was confirmed to be a novel dimethoate amidohydrolase which could eliminate the toxicity of dimethoate, providing a novel gene resource for the development of pesticide-degrading enzyme preparation and mechanistic study of dimethoate hydrolysis.
authors.affiliation: College of Life Sciences, Zaozhuang University, Zaozhuang, 277160, People's Republic of China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Chen
authors.affiliation: Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China.
authors.forename: Kai
authors.initials: K
authors.lastname: Chen
authors.affiliation: Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Ni
authors.affiliation: College of City and Architecture Engineering, Zaozhuang University, Zaozhuang, 277160, People's Republic of China.
authors.forename: Wen
authors.initials: W
authors.lastname: Zhuang
authors.affiliation: College of Life Sciences, Zaozhuang University, Zaozhuang, 277160, People's Republic of China.
authors.forename: Hongmei
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China.
authors.forename: Jianchun
authors.initials: J
authors.lastname: Zhu
authors.affiliation: Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China.
authors.forename: Qin
authors.initials: Q
authors.lastname: He
authors.affiliation: Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China. hejian@njau.edu.cn.
authors.forename: Jian
authors.initials: J
authors.lastname: He
mesh_terms: D000581:Amidohydrolases / Q000235:genetics* / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002264:Carboxylic Acids / Q000737:chemistry; D003001:Cloning, Molecular; D004117:Dimethoate / Q000737:chemistry*; D004926:Escherichia coli / Q000235:genetics; D006868:Hydrolysis; D007306:Insecticides / Q000737:chemistry*; D008744:Methylamines / Q000737:chemistry; D010802:Phylogeny; D020578:Sphingomonas / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D002264:Carboxylic Acids; D007306:Insecticides; D008744:Methylamines; C027451:methylamine; D000581:Amidohydrolases; D004117:Dimethoate
keywords: Amidohydrolase; Dimethoate biodegradation; Organophosphorous pesticide degradation; Sphingomonas sp; dmhA