title: Gene identification and proteomic analysis of the esterases of the cotton bollworm, Helicoverpa armigera.
abstract: Some of the resistance of Helicoverpa armigera to conventional insecticides such as organophosphates and synthetic pyrethroids appears to be due to metabolic detoxification by carboxylesterases. To investigate the H. armigera carboxyl/cholinesterases, we created a data set of 39 putative paralogous H. armigera carboxyl/cholinesterase sequences from cDNA libraries and other sources. Phylogenetic analysis revealed a close relationship between these sequences and 70 carboxyl/cholinesterases from the recently sequenced genome of the silkworm, Bombyx mori, including several conserved clades of non-catalytic proteins. A juvenile hormone esterase candidate from H. armigera was identified, and B. mori orthologues were proposed for 31% of the sequences examined, however low similarity was found between lepidopteran sequences and esterases previously associated with insecticide resistance from other insect orders. A proteomic analysis of larval esterases then enabled us to match seven of the H. armigera carboxyl/cholinesterase sequences to specific esterase isozymes. All identified sequences were predicted to encode catalytically active carboxylesterases, including six proteins with N-terminal signal peptides and N-glycans, with two also containing C-terminal signals for glycosylphosphatidylinositol anchor attachment. Five of these sequences were matched to zones of activity on native PAGE at relative mobility values previously associated with insecticide resistance in this species.
authors.affiliation: CSIRO Entomology, GPO Box 1700, Canberra ACT 2601, Australia.
authors.forename: Mark G
authors.initials: MG
authors.lastname: Teese
authors.forename: Peter M
authors.initials: PM
authors.lastname: Campbell
authors.forename: Colin
authors.initials: C
authors.lastname: Scott
authors.forename: Karl H J
authors.initials: KH
authors.lastname: Gordon
authors.forename: Adam
authors.initials: A
authors.lastname: Southon
authors.forename: Daniel
authors.initials: D
authors.lastname: Hovan
authors.forename: Charles
authors.initials: C
authors.lastname: Robin
authors.forename: Robyn J
authors.initials: RJ
authors.lastname: Russell
authors.forename: John G
authors.initials: JG
authors.lastname: Oakeshott
mesh_terms: D000818:Animals; D043182:Carboxylesterase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002802:Cholinesterases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D007305:Insecticide Resistance; D008969:Molecular Sequence Data; D009036:Moths / Q000737:chemistry / Q000145:classification / Q000201:enzymology* / Q000235:genetics; D009154:Mutation; D010802:Phylogeny; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D040901:Proteomics; D016415:Sequence Alignment
chemical_list: D019476:Insect Proteins; D021382:Protein Sorting Signals; D043182:Carboxylesterase; D002802:Cholinesterases