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 fro m 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 res idues for the putative signal peptide and 600 residues for the mature protein with a predicted molecular weight of 67,994. Northern blot ana lysis of poly(A) RNA showed an approx 13.1-kb transcript, The mature p rotein sequence had 57 and 61% of amino acid residues identical to tho se of Drosophila melanogaster and Anopheles stephensi, respectively, a nd produced a remarkably similar hydropathy profile when compared to t hose of the two dipterous species. The three residues (Ser, Glu and Hi s) 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 m olecular 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 en codes AChE in Colorado potato beetle.