title: Cloning and localization of a glutathione S-transferase class I gene from Anopheles gambiae.
abstract: 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) resistance in both adults and larvae of Anopheles gambiae is mediated by stage-specific glutathione S-transferases (GSTs). On the basis of their biochemical characteristics the larval resistance-associated GSTs are likely to be insect class I GSTs. Aggst1-2, a class I GST gene, which is expressed in larvae, has been cloned from the malaria vector A. gambiae. The gene was inserted into a bacterial expression system, and the detection of 1-chloro-2,4-dinitrobenzene (CDNB) conjugating activity in Eschericia coli expressing the recombinant enzyme confirmed that aggst1-2 encodes a catalytically active GST. The gene encodes a 209 amino acid protein with 46% sequence similarity to a Drosophila melanogaster class I GST (GST-D1), 44% similarity with a Musca domestica class I GST (MdGST-1), but only low levels of homology with class II insect GSTs, including the adult specific AgGST2-1 from A. gambiae. Southern analysis of genomic DNA indicated that A. gambiae has multiple class I GSTs. In situ hybridization of class I genomic and cDNA clones to polytene chromosomes identified a single region of complementarity on chromosome 2R division 18B, suggesting that these class I GSTs in A. gambiae are arranged sequentially in the genome. Three positive overlapping recombinant clones were identified from an A. gambiae genomic library. Mapping and partial sequencing of these clones suggests that there are several GSTs and truncated GST pseudogenes within the 30kb of DNA that these clones span.
authors.affiliation: Department of Pure and Applied Biology, University of Wales, Cardiff CF1 3TL, Wales, United Kingdom.
authors.forename: H
authors.initials: H
authors.lastname: Ranson
authors.forename: A J
authors.initials: AJ
authors.lastname: Cornel
authors.forename: D
authors.initials: D
authors.lastname: Fournier
authors.forename: A
authors.initials: A
authors.lastname: Vaughan
authors.forename: F H
authors.initials: FH
authors.lastname: Collins
authors.forename: J
authors.initials: J
authors.lastname: Hemingway
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000852:Anopheles / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D003634:DDT / Q000494:pharmacology; D018076:DNA, Complementary / Q000737:chemistry; D005982:Glutathione Transferase / Q000235:genetics*; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D015183:Restriction Mapping; D016415:Sequence Alignment
chemical_list: D018076:DNA, Complementary; D003634:DDT; D005982:Glutathione Transferase