Gene_locus Report for: culqu-1estb

Culex quinquefasciatus (Southern house mosquito) C. pipiens, C. pipiens pipiens (Northern house mosquito) (C. pungens) CqestBeta1 CqestB1 Esterase B1, esterase b2 esterase b8 esterase b10 esterase b11

Other strains: Culex quinquefasciatus (Southern house mosquito) (PelRR) Esterase B1 and Culex pipiens (House mosquito) Culex pipiens pipiens (Northern house mosquito) (Culex pungens)

(Below N is a link to NCBI taxonomic web page and E link to ESTHER at designed phylum.)
> cellular organisms: N E > Eukaryota: N E > Opisthokonta: N E > Metazoa: N E > Eumetazoa: N E > Bilateria: N E > Protostomia: N E > Ecdysozoa: N E > Panarthropoda: N E > Arthropoda: N E > Mandibulata: N E > Pancrustacea: N E > Hexapoda: N E > Insecta: N E > Dicondylia: N E > Pterygota: N E > Neoptera: N E > Holometabola: N E > Diptera: N E > Nematocera: N E > Culicomorpha: N E > Culicoidea: N E > Culicidae: N E > Culicinae: N E > Culicini: N E > Culex [genus]: N E > Culex [subgenus]: N E > Culex pipiens complex: N E > Culex quinquefasciatus: N E

Title: Structure of an Insecticide Sequestering Carboxylesterase from the Disease Vector Culex quinquefasciatus: What Makes an Enzyme a Good Insecticide Sponge?
Hopkins DH, Fraser NJ, Mabbitt PD, Carr PD, Oakeshott JG, Jackson CJ
Ref: Biochemistry, 56:5512, 2017 : PubMed
Abstract


ESTHER: Hopkins_2017_Biochemistry_56_5512
PubMedSearch: Hopkins 2017 Biochemistry 56 5512
PubMedID: 28929747
Gene_locus related to this paper: culqu-1estb

Abstract

Carboxylesterase (CBE)-mediated metabolic resistance to organophosphate and carbamate insecticides is a major problem for the control of insect disease vectors, such as the mosquito. The most common mechanism involves overexpression of CBEs that bind to the insecticide with high affinity, thereby sequestering them before they can interact with their target. However, the absence of any structure for an insecticide-sequestering CBE limits our understanding of the molecular basis for this process. We present the first structure of a CBE involved in sequestration, Cqestbeta2(1), from the mosquito disease vector Culex quinquefasciatus. Lysine methylation was used to obtain the crystal structure of Cqestbeta2(1), which adopts a canonical alpha/beta-hydrolase fold that has high similarity to the target of organophosphate and carbamate insecticides, acetylcholinesterase. Sequence similarity networks of the insect carboxyl/cholinesterase family demonstrate that CBEs associated with metabolic insecticide resistance across many species share a level of similarity that distinguishes them from a variety of other classes. This is further emphasized by the structural similarities and differences in the binding pocket and active site residues of Cqestbeta2(1) and other insect carboxyl/cholinesterases. Stopped-flow and steady-state inhibition studies support a major role for Cqestbeta2(1) in organophosphate resistance and a minor role in carbamate resistance. Comparison with another isoform associated with insecticide resistance, Cqestbeta1, showed both enzymes have similar affinity to insecticides, despite 16 amino acid differences between the two proteins. This provides a molecular understanding of pesticide sequestration by insect CBEs and could facilitate the design of CBE-specific inhibitors to circumvent this resistance mechanism in the future.



        

Title: Characterization of novel esterases in insecticide-resistant mosquitoes
Cui F, Weill M, Berthomieu A, Raymond M, Qiao CL
Ref: Insect Biochemistry & Molecular Biology, 37:1131, 2007 : PubMed
Abstract


ESTHER: Cui_2007_Insect.Biochem.Mol.Biol_37_1131
PubMedSearch: Cui 2007 Insect.Biochem.Mol.Biol 37 1131
PubMedID: 17916499
Gene_locus related to this paper: culpi-ESTA, culqu-1estb

Abstract

In the mosquito Culex pipiens complex (Diptera: Culicidae), the amplification of carboxylesterase genes is an important mechanism providing resistance to organophosphate insecticides. Various amplified alleles at the Ester locus have been identified over the world. In this study, two newly detected Ester alleles, Ester(B10) and Ester(11) (including associated Ester(A11) and Ester(B11)), coding for esterases B10 and A11-B11, respectively, are characterized qualitatively and quantitatively. A high molecular identity is observed both at the nucleotide level and at the deduced amino acid level among the known Ester alleles. Real-time quantitative PCR results suggest 2.5-fold amplification of the Ester(B10) allele, 36.5-fold amplification of the Ester(A11) allele, and 19.1-fold amplification of the Ester(B11) allele. The ca. 2-fold difference in amplification level between Ester(A11) and Ester(B11) may indicate a new model for the esterase amplification. Bioassays show that these two resistant Ester alleles only can confer moderate or low resistance to the tested organophosphate insecticides.



        

Title: The independent gene amplification of electrophoretically indistinguishable B esterases from the insecticide-resistant mosquito Culex quinquefasciatus
Vaughan A, Rodriguez M, Hemingway J
Ref: Biochemical Journal, 305 ( Pt 2):651, 1995 : PubMed
Abstract


ESTHER: Vaughan_1995_Biochem.J_305 ( Pt 2)_651
PubMedSearch: Vaughan 1995 Biochem.J 305 ( Pt 2) 651
PubMedID: 7530448
Gene_locus related to this paper: culqu-1estb, culqu-2estb, culqu-3estb

Abstract

Resistance to organophosphates in Culex mosquitoes is typically associated with increased activity of non-specific esterases. The commonest phenotype involves two elevated esterases, A2 and B2, while some strains have elevation of esterase B1 alone. Overexpression of the two B esterase electromorphs is due to gene amplification. Full-length cDNAs coding for amplified esterase B genes from a resistant Cuban strain (MRES, with amplified B1 esterase) and a Sri Lankan strain (PelRR, with amplified B2 esterase) of C. quinquefasciatus have been sequenced. In addition, a partial-length cDNA coding for a B esterase from an insecticide-susceptible Sri Lankan strain (PelSS) has been sequenced. All the nucleotide sequences and the inferred amino acid sequences show a high level of identify (> 95% at the nucleotide and amino acid level), confirming that they are an allelic series. The two B1 esterase nucleotide sequences (MRES and the previously published TEM-R [Mouches, Pauplin, Agarwal, Lemieux, Herzog, Abadon, Beyssat-Arnaouty, Hyrien, De Saint Vincent, Georghiou and Pasteur (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 2574-2578]) showed the lowest identity, and restriction-fragment-length-polymorphism analysis of the two strains was different. On the basis of these data we suggest that the two electrophoretically identical B1 esterase isoenzymes from California and Cuba have been amplified independently. Alternatively, if amplification has occurred only once, the original amplification has not occurred recently.