Characterization of inhibitors and substrates of Anopheles gambiae CYP6Z2

Abstract

Three CYP6Z genes are linked to a major pyrethroid resistance locus in the mosquito Anopheles gambiae. We have expressed CYP6Z2 in Escherichia coli and produced a structural model in order to examine its role in detoxification. E. coli membranes co-expressing CYP6Z2 and An. gambiae P450 reductase (AgCPR) catalysed the dealkylation of benzyloxyresorufin with kinetic parameters K(m) = 0.13 microM; K(cat) = 1.5 min(-1). The IC(50) values of a wide range of compounds were measured. Pyrethroids cypermethrin and permethrin produced low IC(50) values, but were not metabolized. Plant flavanoids were the most potent inhibitors. Several compounds were shown to be substrates, suggesting that CYP6Z2 has broad substrate specificity and plays an important chemo-protective role during the herbivorous phase of the life-cycle.

Identification and validation of a gene causing cross-resistance between insecticide classes inAnopheles gambiaefrom Ghana

“…The Drosophila melanogaster P450, CYP6g1, is associated with resistance to neonicotinoids, the organophosphate malathion and organochlorines DDT and methoxychlor (35)(36)(37)(38). Cross-resistance is arguably an unexpectedly infrequent observation, given the broad substrate specificity of P450s to, for example, plant toxins (39,40).…”

The Role of Anopheles gambiae P450 Cytochrome in Insecticide Resistance and Infection

“…CYP6Z2 was highly over-expressed in a pyrethroidresistant strain (Müller et al, 2007), but opposite to CYP6M2, was down-regulated in the midgut of A. gambiae at day 1 and day 11 after an infected blood meal (Félix et al, 2010). These results suggest a different role for CYP6Z2 in response to the insecticide and to parasite infection, however, we have to take into account that, although being able to bind to permethrin and cypermethrin, CYP6Z2 does not metabolise these compounds (Mclaughlin et al, 2008). So the over-expression of CYP6Z2 in a pyrethroid-resistant strain might be associated with different processes other than insecticide resistance.…”

“…A subsequent study showed that CYP6Z2 displays broad substrate specificity, which may be associated with xenobiotics metabolism and detoxification (Mclaughlin et al, 2008). Despite, CYP6Z2 being able to bind to permethrin and cypermethrin, CYP6Z2 does not metabolise neither one of these insecticides (Mclaughlin et al, 2008). In 2008, Djouaka et al also identified several P450 cytochromes over-expressed in one or more pyrethroid resistant populations of A. gambiae.…”

“…These results, together with their location within a cluster of P450 cytochromes in the right arm of chromosome 3 (3R), which is in close association with a pyrethroid resistance QTL , strongly support their involvement in insecticide resistance. A subsequent study showed that CYP6Z2 displays broad substrate specificity, which may be associated with xenobiotics metabolism and detoxification (Mclaughlin et al, 2008). Despite, CYP6Z2 being able to bind to permethrin and cypermethrin, CYP6Z2 does not metabolise neither one of these insecticides (Mclaughlin et al, 2008).…”

“…They are involved in the metabolism of virtually all insecticides, leading to activation of the molecule in the case of organophosphorus insecticides, or more generally to detoxification (Scott & Wen, 2001). In most cases where a link between insecticide resistance and elevated P450 activity has been shown, the P450 cytochrome belongs to the CYP6 family (Nikou et al, 2003;Djouaka et al, 2008;Müller et al, 2007;McLaughlin et al, 2008). Although being difficult the identification of the specific P450 cytochrome associated with resistance, several P450 cytochromes were already isolated from insecticide resistant strains (Dunkov, et al, 1997;Kasai & Scott, 2000;Sabourault et al, 2001).…”