Acetylcholinesterase (AChE, EC 188.8.131.52), which is encoded by the ace gene, is a key enzyme in both cholinergic system and other non-neuronal tissues. AChE is the target of organophosphates (OP) and carbamates (CA) insecticides. Although AChEs have been extensively studied in lepidopteran pests, no research has been carried out on butterflies, a major subgroup in Lepidoptera. In this study, we cloned two ace genes (Mcace1 and Mcace2) from the Glanville fritillary butterfly (Melitaea cinxia, Lepidoptera: Nymphalidae). The full-length cDNA of Mcace1 was 2433bp, containing a 2073bp ORF encoding 690 amino acids, a 227bp 5’-untranslated region (5’-UTR), and a 133bp 3’-UTR with a poly(A) tail. The cDNA of Mcace2 was 2400bp in length, containing a 1911bp ORF encoding 636 amino acids, a 368bp 5’-UTR, and a 121bp 3’-UTR with a poly(A) tail. Both the deduced proteins, McAChE1 and McAChE2, possess typical features of AChE family, such as catalytic triad, acyl pocket and choline-binding site. Phylogenetic analysis indicated that McAChE1 and McAChE2 exhibited the highest identity to the AChE1 and AChE2 of moths, respectively. We compared the amino acids at the sites where substitution may result in insecticide resistance between McACHEs and the earlier reported AChEs, and found that no amino acid substitution related to insecticide resistance occurs in either McAChE1 or McAChE2. These implied that both McAChE1 and McAChE2 may be sensitive to OP and CA insecticides. The result is compatible with our expectation as no insecticides were used in the habitat of the Glanville fritillary.
amino acid substitution