Characterization of cytochrome P450 genes CYP6A2, CYP6D4 and CYP6D5 in a methoprene resistant strain of Drosophila melanogaster

In insects, cytochrome P450 monooxygenases (P450) are often associated with resistance to insecticides, due to their ubiquitous role in the detoxification of xenobiotics in many organisms. Demonstrating the metabolism of an insecticide by individual P450s and the transcriptional regulation of those P450s is lacking in many cases. Although methoprene resistance in the Rst(1)JH¹ strain of Drosophila melanogaster has been linked to disruption of the Met protein, a transcription factor that binds methoprene, three P450s, CYP6A2, CYP6D4 and CYP6D5 exhibit differential expression in the Rst(1)JH¹, suggesting a metabolic mechanism for methoprene resistance. To test this hypothesis, the three proteins from Rst(1)JH¹ and Oregon-R were expressed in Sf9 cells using a baculovirus expression system and the binding and metabolism of methoprene was measured. In addition, the promoters of CYP6A2, CYP6D4 and CYP6D5 from both strains were isolated and compared for putative regulatory elements that could contribute to the observed differences in expression between the two strains.