Identification and functional analysis of a cytochrome P450 gene CYP9AQ2 involved in deltamethrin detoxification from Locusta migratoria

Abstract

A 1578-bp cDNA of a cytochrome P450 gene (CYP9AQ2) was sequenced from the migratory locust, Locusta migratoria. It contains an open reading frame (ORF) of 1557 bp that encodes 519 amino acid residues. As compared with other known insect cytochrome P450 enzymes, the overall structure of its deduced protein is highly conserved. The expression of CYP9AQ2 was relatively higher in nymphal stages than in egg and adult stages, and the highest expression was found in fourth-instar nymphs, which was 8.7-fold higher than that of eggs. High expression of CYP9AQ2 was observed in foregut, followed by hindgut, Malpighian tubules, brain and fat bodies, which were 75~142-fold higher than that in hemolymph. Low expression was found in midgut, gastric cecum and hemolymph. The expression of CYP9AQ2 was up-regulated by deltamethrin at the concentrations of 0.04, 0.08, and 0.12 µg/mL and the maximal up-regulation was 2.6-fold at LD10 (0.04 µg/mL). RNA interference-mediated silencing of CYP9AQ2 led to an increased mortality of 25.3% when the nymphs were exposed to deltamethrin, suggesting that CYP9AQ2 plays an important role in deltamethrin detoxification in L. migratoria. Computational docking studies suggested that hydroxylation of the phenoxybenzyl moiety might be one of the deltamethrin metabolic pathways by CYP9AQ2.