title: Cytochrome P450 6M2 from the malaria vector Anopheles gambiae metabolizes pyrethroids: Sequential metabolism of deltamethrin revealed.
abstract: Resistance to pyrethroid insecticides in the malaria vector Anopheles gambiae is a major threat to malaria control programmes. Cytochome P450-mediated detoxification is an important resistance mechanism. CYP6M2 is over-expressed in wild populations of permethrin resistant A. gambiae but its role in detoxification is not clear. CYP6M2 was expressed in Escherichia coli and a structural model was produced to examine its role in pyrethroid metabolism. Both permethrin and deltamethrin were metabolized. Rates were enhanced by A. gambiae cytochrome b(5) with kinetic parameters of K(M)=11±1μM and k(cat)=6.1±0.4 per min for permethrin (1:1 cis-trans) and K(M)=2.0±0.3μM and k(cat)=1.2±0.1 per min for deltamethrin. Mass spectrometry and NMR analysis identified 4'-hydroxy deltamethrin and hydroxymethyl deltamethrin as major and minor deltamethrin metabolites respectively. Secondary breakdown products included cyano(3-hydroxyphenyl)methyl deltamethrate and deltamethric acid. CYP6M2 was most highly transcribed in the midgut and Malpighian tubules of adult A. gambiae, consistent with a role in detoxification. Our data indicates that CYP6M2 plays an important role in metabolic resistance to pyrethroids and thus an important target for the design of new tools to combat malaria.
authors.affiliation: Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK.
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: Stevenson
authors.forename: Jaclyn
authors.initials: J
authors.lastname: Bibby
authors.forename: Patricia
authors.initials: P
authors.lastname: Pignatelli
authors.forename: Sant
authors.initials: S
authors.lastname: Muangnoicharoen
authors.forename: Paul M
authors.initials: PM
authors.lastname: O'Neill
authors.forename: Lu-Yun
authors.initials: LY
authors.lastname: Lian
authors.forename: Pie
authors.initials: P
authors.lastname: Müller
authors.forename: Dimitra
authors.initials: D
authors.lastname: Nikou
authors.forename: Andrew
authors.initials: A
authors.lastname: Steven
authors.forename: Janet
authors.initials: J
authors.lastname: Hemingway
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Sutcliffe
authors.forename: Mark J I
authors.initials: MJ
authors.lastname: Paine
mesh_terms: D000818:Animals; D000852:Anopheles / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D001665:Binding Sites; D003001:Cloning, Molecular; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli; D008658:Inactivation, Metabolic; D007303:Insect Vectors / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D016778:Malaria, Falciparum / Q000469:parasitology; D008317:Malpighian Tubules / Q000187:drug effects / Q000201:enzymology*; D013058:Mass Spectrometry; D008958:Models, Molecular; D009570:Nitriles / Q000494:pharmacology*; D026023:Permethrin / Q000494:pharmacology*; D010957:Plasmids; D010963:Plasmodium falciparum / Q000502:physiology; D011485:Protein Binding; D011722:Pyrethrins / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; D011994:Recombinant Proteins; C017180:decamethrin; D026023:Permethrin; D003577:Cytochrome P-450 Enzyme System