Cha DJ

References (4)

Title : Evolutionary origin and status of two insect acetylcholinesterases and their structural conservation and differentiation - Cha_2015_Evol.Dev_17_109
Author(s) : Cha DJ , Lee SH
Ref : Evol Dev , 17 :109 , 2015
Abstract : Acetylcholinesterase (AChE) plays a pivotal role in synaptic transmission in the cholinergic nervous system of most animals, including insects. Insects possess duplicated AChE gene loci (ace1 vs. ace2) encoding two distinct AChEs (AChE1 and AChE2). A phylogenetic analysis suggested that the last common ancestor of two aces shared its origin with Platyhelminthes. In addition, the ace duplication event likely occurred after the divergence of Protostomian but before the split of Ecdysozoa. The ace1 lineage exhibited a significantly lower evolutionary rate (d and dN/dS ratio) than the ace2 lineage, suggesting that the ace1 lineage has retained the essential function of synaptic transmission following its duplication. Therefore, the putative functional transition from ace1 to ace2 observed in some Hymenopteran insects appears to be a local and relatively recent event. The amino acid sequence comparison and three-dimensional modeling of insect AChEs identified a few consistent differences in the amino acid residues in functionally crucial domains between two AChEs, which are likely responsible for the functional differentiation between two AChEs. A unique amino acid substitution causing a dramatic reduction in the catalytic activity of AChE1 in some Hymenopteran insects was suggested to be responsible for the aforementioned functional transition of ace.
ESTHER : Cha_2015_Evol.Dev_17_109
PubMedSearch : Cha_2015_Evol.Dev_17_109
PubMedID: 25627717

Title : Mutation and duplication of arthropod acetylcholinesterase: Implications for pesticide resistance and tolerance - Lee_2015_Pestic.Biochem.Physiol_120_118
Author(s) : Lee SH , Kim YH , Kwon DH , Cha DJ , Kim JH
Ref : Pestic Biochem Physiol , 120 :118 , 2015
Abstract : A series of common/shared point mutations in acetylcholinesterase (AChE) confers resistance to organophosphorus and carbamate insecticides in most arthropod pests. However, the mutations associated with reduced sensitivity to insecticides usually results in the reduction of catalytic efficiency and leads to a fitness disadvantage. To compensate for the reduced catalytic activity, overexpression of neuronal AChE appears to be necessary, which is achieved by a relatively recent duplication of the AChE gene (ace) as observed in the two-spotted spider mite and other insects. Unlike the cases with overexpression of neuronal AChE, the extensive generation of soluble AChE is observed in some insects either from a distinct non-neuronal ace locus or from a single ace locus via alternative splicing. The production of soluble AChE in the fruit fly is induced by chemical stress. Soluble AChE acts as a potential bioscavenger and provides tolerance to xenobiotics, suggesting its role in chemical adaptation during evolution.
ESTHER : Lee_2015_Pestic.Biochem.Physiol_120_118
PubMedSearch : Lee_2015_Pestic.Biochem.Physiol_120_118
PubMedID: 25987229

Title : Molecular and kinetic properties of two acetylcholinesterases from the western honey bee, Apis mellifera - Kim_2012_PLoS.One_7_e48838
Author(s) : Kim YH , Cha DJ , Jung JW , Kwon HW , Lee SH
Ref : PLoS ONE , 7 :e48838 , 2012
Abstract : We investigated the molecular and kinetic properties of two acetylcholinesterases (AmAChE1 and AmAChE2) from the Western honey bee, Apis mellifera. Western blot analysis revealed that AmAChE2 has most of catalytic activity rather than AmAChE1, further suggesting that AmAChE2 is responsible for synaptic transmission in A. mellifera, in contrast to most other insects. AmAChE2 was predominately expressed in the ganglia and head containing the central nervous system (CNS), while AmAChE1 was abundantly observed not only in the CNS but also in the peripheral nervous system/non-neuronal tissues. Both AmAChEs exist as homodimers; the monomers are covalently connected via a disulfide bond under native conditions. However, AmAChE2 was associated with the cell membrane via the glycophosphatidylinositol anchor, while AmAChE1 was present as a soluble form. The two AmAChEs were functionally expressed with a baculovirus system. Kinetic analysis revealed that AmAChE2 has approximately 2,500-fold greater catalytic efficiency toward acetylthiocholine and butyrylthiocholine than AmAChE1, supporting the synaptic function of AmAChE2. In addition, AmAChE2 likely serves as the main target of the organophosphate (OP) and carbamate (CB) insecticides as judged by the lower IC(50) values against AmAChE2 than against AmAChE1. When OP and CB insecticides were pre-incubated with a mixture of AmAChE1 and AmAChE2, a significant reduction in the inhibition of AmAChE2 was observed, suggesting a protective role of AmAChE1 against xenobiotics. Taken together, based on their tissue distribution pattern, molecular and kinetic properties, AmAChE2 plays a major role in synaptic transmission, while AmAChE1 has non-neuronal functions, including chemical defense.
ESTHER : Kim_2012_PLoS.One_7_e48838
PubMedSearch : Kim_2012_PLoS.One_7_e48838
PubMedID: 23144990
Gene_locus related to this paper: apime-ACHE , apime-ACHE1

Title : Cloning of the acetylcholinesterase 1 gene and identification of point mutations putatively associated with carbofuran resistance in Nilaparvata lugens - Kwon_2012_Pestic.Biochem.Physiol_103_94
Author(s) : Kwon DH , Cha DJ , Kim YH , Lee SW , Lee SH
Ref : Pesticide Biochemistry and Physiology , 103 :94 , 2012
Abstract : Molecular mechanisms of carbofuran resistance in the brown planthopper, Nilaparvata lugens Stl, were investigated. A carbofuran-resistant strain (CAS) showed approximately 45.5- and 15.1-fold resistance compared with a susceptible strain (SUS) and a non-selected field strain (FM), respectively. Activities of the esterase and mixed-function oxidase were approximately 2.8- and 1.6-fold higher, respectively, in the CAS strain than in the SUS strain, suggesting that these enzymes play a minor role in carbofuran resistance. Interestingly, the insensitivity of acetylcholinesterase (AChE) to carbofuran was approximately 5.5- and 3.7-fold higher in the CAS strain compared to the SUS and FM strains, respectively, indicating that AChE insensitivity is associated with carbofuran resistance. Western blot analysis identified two kinds of AChEs, of which the type-1 AChE (encoded from Nlace1, which is paralogous to the Drosophila AChE gene) was determined to be the major catalytic AChE in N. lugens. The open reading frame of Nlace1 is composed of 1989 bp (approximately 74 kD) and revealed 52.5% and 24.3% amino acid sequence identities to those of Nephotettix cincticeps and Drosophila melanogaster, respectively. Screening of point mutations identified four amino acid substitutions (G119A, F/Y330S, F331H and H332L) in the CAS strain that likely contribute to AChE insensitivity. The frequencies of these mutations were well correlated with resistance levels, confirming that they are associated with reduced sensitivity to carbofuran in N. lugens. These point mutations can be useful as genetic markers for monitoring resistance levels in field populations of N. lugens.
ESTHER : Kwon_2012_Pestic.Biochem.Physiol_103_94
PubMedSearch : Kwon_2012_Pestic.Biochem.Physiol_103_94
Gene_locus related to this paper: nillu-ACHE1