title: The role of the Aedes aegypti Epsilon glutathione transferases in conferring resistance to DDT and pyrethroid insecticides.
abstract: The Epsilon glutathione transferase (GST) class in the dengue vector Aedes aegypti consists of eight sequentially arranged genes spanning 53,645 bp on super contig 1.291, which maps to chromosome 2. One Epsilon GST, GSTE2, has previously been implicated in conferring resistance to DDT. The amino acid sequence of GSTE2 in an insecticide susceptible and a DDT resistant strain differs at five residues two of which occur in the putative DDT binding site. Characterization of the respective recombinant enzymes revealed that both variants have comparable DDT dehydrochlorinase activity although the isoform from the resistant strain has higher affinity for the insecticide. GSTe2 and two additional Epsilon GST genes, GSTe5 and GSTe7, are expressed at elevated levels in the resistant population and the recombinant homodimer GSTE5-5 also exhibits low levels of DDT dehydrochlorinase activity. Partial silencing of either GSTe7 or GSTe2 by RNA interference resulted in an increased susceptibility to the pyrethroid, deltamethrin suggesting that these GST enzymes may also play a role in resistance to pyrethroid insecticides.
authors.affiliation: Research Institute for Health Sciences, Chiang Mai University, 110 Intavaroros Road, Chiang Mai, 50200, Thailand. nklumjuan@yahoo.com
authors.forename: Nongkran
authors.initials: N
authors.lastname: Lumjuan
authors.forename: Shavanthi
authors.initials: S
authors.lastname: Rajatileka
authors.forename: Donch
authors.initials: D
authors.lastname: Changsom
authors.forename: Jureeporn
authors.initials: J
authors.lastname: Wicheer
authors.forename: Posri
authors.initials: P
authors.lastname: Leelapat
authors.forename: La-aied
authors.initials: LA
authors.lastname: Prapanthadara
authors.forename: Pradya
authors.initials: P
authors.lastname: Somboon
authors.forename: Gareth
authors.initials: G
authors.lastname: Lycett
authors.forename: Hilary
authors.initials: H
authors.lastname: Ranson
mesh_terms: D000330:Aedes / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D003634:DDT / Q000378:metabolism / Q000494:pharmacology*; D005260:Female; D005786:Gene Expression Regulation; D005982:Glutathione Transferase / Q000235:genetics* / Q000378:metabolism; D007305:Insecticide Resistance; D008190:Lyases / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D009570:Nitriles / Q000378:metabolism / Q000494:pharmacology*; D011722:Pyrethrins / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D009570:Nitriles; D011722:Pyrethrins; C017180:decamethrin; D003634:DDT; D005982:Glutathione Transferase; D008190:Lyases; C019990:DDT-dehydrochlorinase