Cloning and sequencing of a cDNA encoding acetylcholinesterase in Colorado potato beetle, Leptinotarsa decemlineata (Say)

A cDNA encoding acetylcholinesterase (AChE, EC 1.1.1.7) was cloned from a cDNA library constructed from an insecticide-susceptible strain of Colorado potato beetle, Leptinotarsa decemlineata (Say), The complete amino acid sequence of AChE deduced from the cDNA consisted of 29 residues for the putative signal peptide and 600 residues for the mature protein with a predicted molecular weight of 67,994. Northern blot analysis of poly(A) RNA showed an approx 13.1-kb transcript, The mature protein sequence had 57 and 61% of amino acid residues identical to those of Drosophila melanogaster and Anopheles stephensi, respectively, and produced a remarkably similar hydropathy profile when compared to those of the two dipterous species. The three residues (Ser, Glu and His) that putatively form the catalytic triad and the six Cys that form intra-subunit disulfide bonds were completely conserved when compared to the other seven AChEs from a broad range of animal species reported to date, Other properties of the deduced protein of AChE, including molecular weight and amino acid composition, agreed well with those of a previously reported study on the purified AChE from the same insect species. All these features firmly established that the cloned cDNA encodes AChE in Colorado potato beetle.