title: Molecular characterization of the amplified aldehyde oxidase from insecticide resistant Culex quinquefasciatus.
abstract: Primary structural information including the complete nucleotide sequence of the first insect aldehyde oxidase (AO) was obtained from the common house mosquito Culex quinquefasciatus (Say) through cloning and sequencing of both genomic DNA and cDNA. The deduced amino-acid sequence encodes a 150-kDa protein of 1266 amino-acid residues, which is consistent with the expected monomeric subunit size of AO. The Culex AO sequence contains a molybdopterin cofactor binding domain and two iron-sulfur centres. A comparison of the partial sequences of AO from insecticide resistant and susceptible strains of C. quinquefasciatus shows two distinct alleles of this enzyme, one of which is amplified in the insecticide resistant strain on a 30-kb DNA amplicon alongside two resistance-associated esterases. The amplified AO gene results in elevated AO activity in all life stages, but activity is highest in 3rd instar larvae. The elevated enzyme can be seen as a separate band on polyacrylamide gel electrophoresis. The role of AO in xenobiotic oxidation in mammals and the partial inhibition of elevated AO activity by a range of insecticides in Culex, suggest that this AO may play a role in insecticide resistance.
authors.affiliation: Liverpool School of Tropical Medicine, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Coleman
authors.forename: John G
authors.initials: JG
authors.lastname: Vontas
authors.forename: Janet
authors.initials: J
authors.lastname: Hemingway
mesh_terms: D020413:3' Untranslated Regions; D000444:Aldehyde Dehydrogenase / Q000235:genetics / Q000378:metabolism; D042931:Aldehyde Oxidase; D000445:Aldehyde Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D003067:Coenzymes; D017124:Conserved Sequence; D003465:Culex / Q000187:drug effects / Q000201:enzymology* / Q000502:physiology; D004351:Drug Resistance / Q000235:genetics; D015180:Electrophoresis, Gel, Two-Dimensional; D015971:Gene Expression Regulation, Enzymologic; D007306:Insecticides / Q000494:pharmacology; D007506:Iron-Sulfur Proteins / Q000235:genetics / Q000378:metabolism; D007814:Larva; D008667:Metalloproteins / Q000378:metabolism; D008969:Molecular Sequence Data; D000090006:Molybdenum Cofactors; D011621:Pteridines / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D020413:3' Untranslated Regions; D000444:Aldehyde Dehydrogenase; D042931:Aldehyde Oxidase; D000445:Aldehyde Oxidoreductases; D003067:Coenzymes; D007306:Insecticides; D007506:Iron-Sulfur Proteins; D008667:Metalloproteins; D000090006:Molybdenum Cofactors; D011621:Pteridines; C022261:molybdopterin