title: Elevated activity of an Epsilon class glutathione transferase confers DDT resistance in the dengue vector, Aedes aegypti.
abstract: Glutathione transferases (GSTs) play a central role in the detoxification of xenobiotics such as insecticides and elevated GST expression is an important mechanism of insecticide resistance. In the mosquito, Anopheles gambiae, increased expression of an Epsilon class GST, GSTE2, confers resistance to DDT. We have identified eight GST genes in the dengue vector, Aedes aegypti. Four of these belong to the insect specific GST classes Delta and Epsilon and three are from the more ubiquitously distributed Theta and Sigma classes. The expression levels of the two Epsilon genes, a Theta GST and a previously identified Ae. aegypti GST [Grant and Hammock, 1992. Molecular and General Genetics 234, 169-176] were established for an insecticide susceptible and a resistant strain. We show that the putative ortholog of GSTe2 in Ae. aegypti (AaGSTe2) is over expressed in mosquitoes that are resistant to the insecticides DDT and permethrin. Characterisation of recombinant AaGSTE2-2 confirmed the role of this enzyme in DDT metabolism. In addition, unlike its Anopheles ortholog, AaGSTE2-2 also exhibited glutathione peroxidase activity.
authors.affiliation: Vector Research Group, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK.
authors.forename: Nongkran
authors.initials: N
authors.lastname: Lumjuan
authors.forename: Lynn
authors.initials: L
authors.lastname: McCarroll
authors.forename: La-aied
authors.initials: LA
authors.lastname: Prapanthadara
authors.forename: Janet
authors.initials: J
authors.lastname: Hemingway
authors.forename: Hilary
authors.initials: H
authors.lastname: Ranson
mesh_terms: D000330:Aedes / Q000235:genetics* / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D003634:DDT / Q000378:metabolism / Q000494:pharmacology*; D003715:Dengue / Q000635:transmission; D005786:Gene Expression Regulation; D005982:Glutathione Transferase / Q000235:genetics* / Q000502:physiology; D007300:Insect Control; D007303:Insect Vectors; D007305:Insecticide Resistance / Q000235:genetics; D007306:Insecticides / Q000378:metabolism / Q000494:pharmacology*; D008969:Molecular Sequence Data
chemical_list: D007306:Insecticides; D003634:DDT; D005982:Glutathione Transferase