(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 > Prosorrhyncha: NE > Heteroptera: NE > Euheteroptera: NE > Neoheteroptera: NE > Panheteroptera: NE > Cimicomorpha: NE > Cimicoidea: NE > Cimicidae: NE > Cimex: NE > Cimex lectularius: 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 MRWLLVATVVLGAGASPPLDDDPLIIETDKGRVRGITIAASTGKLVDAWL GIPYAQKPIGKLRFRHPRPLDKWNHILNATRLPNTCVQIIDTVFGDFPGA IIWNPNTQLSEDCLYLNVVVPKPRPTNAAVMVWIFGGGFYSGSATLDVYD HKTLVSEENVILVSMQYRVASLGFLYLDTADVPGNAGLYDQRMALQWVHD NIHLFGGDPQKVTLFGESAGAVSVSLHLLSPLSHKLFNQAIMESGSAVAP WAIISREESMLRGLRLAEAVGCPHSKHELRAVIDCLRNTNATDLVSNEWG TLGICEFPFVPIVDGTFVDDHPKRNLAARNFKKTNILMGSNTEEGYYFII YYLTELFRKEENVYINREEFLRAVVELNPYVNNIARQAIIFEYTDWQNPE DPIKNRDALDKMVGDYQFTCTVNEFAHTYAESGNVVYMYLFSHRSIGNPW PSWTGVMHGDEINYVFGEPLNPTKNYLPSEAELSRRMMNYWANFAKTGNP NLKGNNSWTSTYWPQHTAYGREFLTLGINQSSSTTGRGPRVKQCAFWKKY LPQLIASTETRTNPVQECTNGVNSLSLSKELLPAAVAFFAALTVYV
Bed bug control highly depends on insecticides with a limited number of modes of action, especially since the global prevalence of pyrethroid resistance. De facto insecticide options against bed bugs in Japan are acetylcholinesterase inhibitors (AChEis) that consist of organophosphates and carbamates. However, the status of AChEi resistance and the mechanisms involved have not been ascertained. An amino acid substitution mutation, F348Y (or F331Y in standard numbering), occurring at an acyl-binding site of the paralogous AChE gene (p-Ace), was identified among AChEi-resistant colonies of both common and tropical bed bugs (Cimex lectularius and C. hemipterus, respectively). This mutation was genetically associated with propoxur and fenitrothion resistance in F348Y-segregating colonies of C. hemipterus. Inhibition of heterologously expressed C. lectularius p-Ace with insecticides revealed that the sensitivities of F348Y-carrying AChE decreased by orders of 10- to more than 100-fold for diazoxon, carbaryl, fenitroxon, paraoxon, chlorpyrifos-methyl, malaoxon, azamethiphos, methyl-paraoxon, and propoxur. In contrast, the mutant AChE showed a slightly decreased degree of sensitivity for dichlorvos and almost unchanged sensitivity for metoxadiazone. Further studies are needed to ascertain whether the practical efficacies of dichlorvos and metoxadiazone are ensured against F348Y-carrying bed bugs and whether other resistance mechanisms are involved.
Title: Biochemical and toxicological properties of two acetylcholinesterases from the common bed bug, Cimex lectularius Hwang CE, Kim YH, Kwon DH, Seong KM, Choi JY, Je YH, Lee SH Ref: Pestic Biochem Physiol, 110:20, 2014 : PubMed
We examined the molecular and enzymatic properties of two acetylcholinesterases (AChEs; ClAChE1 and ClAChE2) from the common bed bug, Cimex lectularius. Native polyacrylamide gel electrophoresis followed by activity staining and Western blotting revealed that ClAChE1 is the main catalytic enzyme and is abundantly expressed in various tissues. Both ClAChEs existed in dimeric form connected by a disulfide bridge and were attached to the membrane via a glycophosphatidylinositol anchor. To determine their kinetic and inhibitory properties, both ClAChE1 and ClAChE2 were in vitro expressed in Sf9 cells using a baculovirus expression system. ClAChE1 showed higher catalytic efficiency toward acetylcholine, supporting the hypothesis that ClAChE1 plays a major role in postsynaptic transmission. An inhibition assay revealed that ClAChE1 is generally more sensitive to organophosphates and carbamates examined although ClAChE2 was >4000-fold more sensitive to malaoxon than ClAChE1. The relatively higher correlation between the in vitro ClAChE1 inhibition and the in vivo toxicity suggested that ClAChE1 is the more relevant toxicological target for organophosphates and carbamates. Although the physiological function of ClAChE2 remains to be elucidated, ClAChE2 also appears to have neuronal functions, as judged by its tissue distribution and molecular and kinetic properties. Our findings help expand our knowledge on insect AChEs and their toxicological properties.
Title: Identification and characterization of three cholinesterases from the common bed bug, Cimex lectularius Seong KM, Kim YH, Kwon DH, Lee SH Ref: Insect Molecular Biology, 21:149, 2012 : PubMed
We identified and characterized the full-length cDNA sequences encoding two acetylcholinesterases (ClAChE1 and ClAChE2) and a salivary gland-specific cholinesterase-like protein (ClSChE) from the common bed bug, Cimex lectularius. All three cholinesterase genes (Clac1, Clace2 and Clsce) have conserved motifs, including a catalytic triad, a choline-binding site and an acyl pocket. Phylogenetic analysis showed that ClAChE1 belongs to the insect AChE1 clade, whereas ClAChE2 belongs to the insect AChE2 clade. ClSChE was grouped into the clade containing all AChE1s, suggesting a paralogous relationship to ClAChE1. Transcription levels of Clace1 were higher than those of Clace2 in all tissues examined, including the central nervous system (CNS). In contrast, the Clsce transcript was not detected in the CNS but specifically found in the salivary gland at much higher levels (>3000-fold) than those of Clace1 and Clace2. Western blot analysis using anti-ClAChE antibodies, in conjunction with activity staining, revealed that ClAChE1 is more active than ClAChE2, whereas ClSChE has little enzyme activity. Three-dimensional structure modelling suggested that ClAChEs and ClSChE shared structural similarities, but had some differences in the residues forming the acyl pocket and oxyanion hole. The current findings should provide valuable insights into the evolution and functional diversification of insect cholinesterase.
