(Below N is a link to NCBI taxonomic web page and E link to ESTHER at designed phylum.) > cellular organisms: NE > Eukaryota: NE > Opisthokonta: NE > Metazoa: NE > Eumetazoa: NE > Bilateria: NE > Protostomia: NE > Ecdysozoa: NE > Panarthropoda: NE > Arthropoda: NE > Mandibulata: NE > Pancrustacea: NE > Hexapoda: NE > Insecta: NE > Dicondylia: NE > Pterygota: NE > Neoptera: NE > Paraneoptera: NE > Hemiptera: NE > Sternorrhyncha: NE > Aleyrodoidea: NE > Aleyrodidae: NE > Aleyrodinae: NE > Bemisia: NE > Bemisia tabaci: NE
LegendThis sequence has been compared to family alignement (MSA) red => minority aminoacid blue => majority aminoacid color intensity => conservation rate title => sequence position(MSA position)aminoacid rate Catalytic site Catalytic site in the MSA MATPATTRVVTQRQRREPCPRGTKELWPLALTLCAVLGLAAGHPSHRKHH GQTSHLNNHKNHNFDEDHYASFAAYQEPSNKTGTSNGDRKFKAGEEERKY IFDGQRRFKSLEHERHTHADYEESFVNDPLVVRTKSGLIRGVEKQVMGHK VHVFTGIPFAKPPVGMLRFRKPVEIDPWRGVLNATSLPNSCYQERLEYFP GFQGEEMWNPNTNISEDCLYLNLWVPQKMRLRHRRHIHQKAPVLIWIYGG GYMTGTSTLELYDADIVAGVCNVIVASLQYRVGSFGFLYLKPLLPEGIEE APGNMGLWDQAMAIKWIKDNIAAFGGDPDMLTLFGESAGGSSVNIHLISP VTKGLARRGILQSGTLNMPWSYMEAEKAMQIGKILVDDCNCNSSQLEENP TKVFACMRAVDAKIVSSQQWSSYFGILGYPSAPTIDGEFLPKHPLELMKD QNFEDIELLIGSNRDEGTYFLLYDFLEFFEKDGPSLLQRDKFLDIIHTIF KNFSPLEKEAIIFQYTDWENLGDGYTNQKMIGEIVGDYFFICPSNYFAQV MSDNGAKIYYYYFTQRTSTNLWGEWMGVMHGDEVEYVFGHPLNMSLQYNA RERDLSNRIMEAFSKFAMTGKPTGEDVTWPQYTRSNPQYFIFHATTSGLG SGPRLTACQFWNEFLPKLRNVSENISSTTDIKSCCSQEMSLGDCNNTALR VSDSGGRAAPEMGFLLLALFPVLLTSIR
References
Title: Molecular and kinetic characterization of two acetylcholinesterases with particular focus on the roles of two amino acid substitutions (Y390N and F392W) in Bemisia tabaci Kim S, Yoon KA, Cho S, Lee SH Ref: Pestic Biochem Physiol, 182:105039, 2022 : PubMed
Two acetylcholinesterases (AChEs) are present in Bemisia tabaci (BtAChE1 and BtAChE2). A conserved AChE mutation conferring organophosphate (OP) resistance (F392W in BtAChE1) is saturated in field populations despite its potential fitness cost, and a highly conserved amino acid residue forming the backdoor of AChE is substituted with a unique amino acid (Y390N in BtAChE1) in B. tabaci. Thus, the roles and relationships of the two amino acid substitutions in the evolutionary adaptation of B. tabaci remain to be elucidated, and little information is available on the catalytic and molecular properties of BtAChE1 and BtAChE2. To determine which AChE is a more relevant target of OPs and carbamates, the molecular and kinetic properties of BtAChE1 and BtAChE2 were investigated. Both BtAChE1 and BtAChE2 were exclusively expressed in head and thorax but not in abdomen, bound to the membrane via GPI anchoring, and present as dimeric forms. Soluble monomeric form was detected only in BtAChE2. The catalytic activity of baculovirus-expressed BtAChE1 was 19.5-fold higher than that of BtAChE2. The inhibition assay revealed that the F392W mutation in BtAChE1 enhanced resistance to OPs. The artificial substitution of N390 (wild form) to Y (putative ancient form) led to reduced catalytic efficiency and increased inhibition by glycoalkaloids, suggesting that the Y390N substitution in BtAChE1 may have been required for Solanaceae host adaptation. BtAChE1 was proven to function as a main catalytic enzyme for ACh hydrolysis, thus being the main target of OPs and carbamates.
Title: Organophosphates' resistance in the B-biotype of Bemisia tabaci (Hemiptera: Aleyrodidae) is associated with a point mutation in an ace1-type acetylcholinesterase and overexpression of carboxylesterase Alon M, Alon F, Nauen R, Morin S Ref: Insect Biochemistry & Molecular Biology, 38:940, 2008 : PubMed
Organophosphate (OP) insecticides are inhibitors of the enzyme acetylcholinesterase (AChE), which terminates nerve impulses by catalyzing the hydrolysis of the neurotransmitter acetylcholine. Previous biochemical studies in Bemisia tabaci (Hemiptera: Aleyrodidae) proposed the existence of two molecular mechanisms for OPs' resistance: carboxylesterase- (COE) mediated hydrolysis or sequestration and decreased sensitivity of AChE. Here, two acetylcholinesterase genes, ace1 and ace2, have been fully cloned and sequenced from an OP-resistant strain and an OP-susceptible strain of B. tabaci. Comparison of nucleic acid and deduced amino acid sequences revealed only silent nucleotide polymorphisms in ace2, and one mutation, Phe392Trp (Phe331 in Torpedo californica), in ace1 of the resistant strain. The Phe392Trp mutation is located in the acyl pocket of the active site gorge and was recently shown to confer OP insensitivity in Culex tritaeniorhynchus. In addition, we also report on the isolation of two carboxylesterase genes (coe1 and coe2) from B. tabaci, the first carboxylesterases to be reported from this species. We show that one of the genes, coe1, is overexpressed ( approximately 4-fold) in the OP-resistant strain, and determine, by quantitative PCR, that the elevated expression is not related to gene amplification but probably to modified transcriptional control. Lastly, we bring new biochemical evidence that support the involvement of both AChE insensitivity and COE metabolism in resistance to OP insecticides in the resistant strain.
Title: Characterization of acetylcholinesterases, and their genes, from the hemipteran species Myzus persicae (Sulzer), Aphis gossypii (Glover), Bemisia tabaci (Gennadius) and Trialeurodes vaporariorum (Westwood) Javed N, Viner R, Williamson MS, Field LM, Devonshire AL, Moores GD Ref: Insect Molecular Biology, 12:613, 2003 : PubMed
Gene sequences encoding putative acetylcholinesterases have been reported for four hemipteran insect species. Although acetylcholinesterase insensitivity occurs in insecticide-resistant populations of each of these species, no mutations were detected in the gene sequences from the resistant insects. This, coupled with a series of experiments using novel reversible inhibitors to compare the biochemical characteristics of acetylcholinesterase from a range of insect species, showed that the cloned cDNA fragments are unlikely to encode the hemipteran synaptic acetylcholinesterases, and there is likely to be a second ace locus.
