Cytochrome P450 6M2 from the malaria vector Anopheles gambiae metabolizes pyrethroids: Sequential metabolism of deltamethrin revealed

• Published in: Insect biochemistry and molecular biology 2011-07, Vol.41 (7), p.492-502
• Main Authors: Stevenson, Bradley J., Bibby, Jaclyn, Pignatelli, Patricia, Muangnoicharoen, Sant, O’Neill, Paul M., Lian, Lu-Yun, Müller, Pie, Nikou, Dimitra, Steven, Andrew, Hemingway, Janet, Sutcliffe, Michael J., Paine, Mark J.I.
• Format: Article
• Language: English
• Subjects: Animals; Anopheles - drug effects; Anopheles - enzymology; Anopheles - genetics; Anopheles gambiae; Binding Sites; Cloning, Molecular; cytochrome P-450; Cytochrome P-450 Enzyme System - genetics; Cytochrome P-450 Enzyme System - metabolism; deltamethrin; Detoxification; Escherichia coli; Inactivation, Metabolic; Insect Vectors - drug effects; Insect Vectors - enzymology; Insect Vectors - genetics; Insecticide Resistance; Insecticides - pharmacology; Kinetics; Magnetic Resonance Spectroscopy; Malaria; Malaria, Falciparum - parasitology; Malpighian tubules; Malpighian Tubules - drug effects; Malpighian Tubules - enzymology; Mass Spectrometry; metabolism; metabolites; midgut; Mixed-function oxidase; Models, Molecular; Mosquito; Nitriles - pharmacology; nuclear magnetic resonance spectroscopy; permethrin; Permethrin - pharmacology; Plasmids; Plasmodium falciparum - physiology; Protein Binding; pyrethrins; Pyrethrins - pharmacology; Recombinant Proteins - genetics; Recombinant Proteins - metabolism
• ISSN: 0965-1748; 1879-0240
• DOI: 10.1016/j.ibmb.2011.02.003

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 b5 with kinetic parameters of KM=11±1μM and kcat=6.1±0.4 per min for permethrin (1:1 cis–trans) and KM=2.0±0.3μM and kcat=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. [Display omitted] ► CYP6M2 metabolizes permethrin and deltamethrin. ► Deltamethin undergoes complex primary and secondary metabolism. ► CYP6M2 appears most highly transcribed in Malphigian tubules.