title: Two single mutations commonly cause qualitative change of nonspecific carboxylesterases in insects.
abstract: Carboxylesterases provide key mechanisms of resistance to insecticides, particularly organophosphates (OPs), in insects. One resistance mechanism is a qualitative change in the properties of a carboxylesterase. Two mutant forms, G151D and W271L, have been observed, mostly in dipteran species, to affect substrate specificity of enzymes. But whether these two single mutations can commonly change character of insect carboxylesterases is unknown. In our study carboxylesterase genes from seven insects distributed among four orders were cloned, mutated at position 151 or 271 and expressed in Escherichia coli. The kinetics of the purified recombinant proteins was examined towards an artificial carboxylester and two OP insecticides. The G/A151D and W271L mutation significantly reduced carboxylesterase activity in 87.5% and 100% cases, respectively, and at the same time conferred OP hydrolase activities in 62.5% and 87.5% cases, respectively. Thus, the change at position 271 is more effective to influence substrate specificity than that at position 151. These results may suggest that these two mutations have the potential to cause insecticide resistance broadly in insects.
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects & Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Cui
authors.forename: Zhe
authors.initials: Z
authors.lastname: Lin
authors.forename: Hongsheng
authors.initials: H
authors.lastname: Wang
authors.forename: Silu
authors.initials: S
authors.lastname: Liu
authors.forename: Haijing
authors.initials: H
authors.lastname: Chang
authors.forename: Gerald
authors.initials: G
authors.lastname: Reeck
authors.forename: Chuanling
authors.initials: C
authors.lastname: Qiao
authors.forename: Michel
authors.initials: M
authors.lastname: Raymond
authors.forename: Le
authors.initials: L
authors.lastname: Kang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002265:Carboxylic Ester Hydrolases / Q000235:genetics* / Q000378:metabolism; D004175:Diptera / Q000201:enzymology / Q000235:genetics*; D004926:Escherichia coli; D017344:Genes, Insect; D007305:Insecticide Resistance / Q000187:drug effects / Q000235:genetics*; D007306:Insecticides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D008969:Molecular Sequence Data; D009154:Mutation; D010755:Organophosphates / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D010802:Phylogeny; D011994:Recombinant Proteins / Q000235:genetics* / Q000378:metabolism; D013379:Substrate Specificity / Q000235:genetics
chemical_list: D007306:Insecticides; D010755:Organophosphates; D011994:Recombinant Proteins; D002265:Carboxylic Ester Hydrolases