中文摘要：

利用RT-PCR结合RACE技术克隆了甘薯茎线虫（Ditylenchus destructor）乙酰胆碱酯酶基因cDNA,Dd-ace-3,提交GenBank登录号EF583057。该cDNA序列5＇端存在反式剪接引导序列SL1,全长2517bp,包含一个1836bp的开放阅读框;在推导出的611个氨基酸残基的前体蛋白中,N端的前21个氨基酸残基为信号肽,C-28的位置存在糖基磷脂酰肌醇（GPI）锚定位点,除此之外的562个氨基酸残基是成熟的乙酰胆碱酯酶序列,其预测的分子量为64396.81D。在一级结构中,形成催化活性中心的3个氨基酸残基（Ser232、Glu360和His479）,以及在亚基内形成二硫键的6个半胱氨酸完全保守;在电鳐乙酰胆碱酯酶分子的催化功能域中存在14个保守的芳香族氨基酸残基,其中12个在甘薯茎线虫乙酰胆碱酯酶中完全保守。该酶的氨基酸序列与秀丽小杆线虫（Caenorhabditis elegans）ACE-3和ACE-4的同源性达56.1%和50.0%。与其它线虫和物种乙酰胆碱酯酶的聚类分析显示,甘薯茎线虫的乙酰胆碱酯酶与Ⅲ型乙酰胆碱酯酶ACE-3同属一个支系。

英文摘要：

A new cDNA, named Dd-ace-3, encoding an acetylcholinesterase （AChE, EC3.1.1.7） was isolated from the sweet potato stem nematode （Ditylenchus destructor）. The full-length cDNA, carrying the trans-spliced SL1 leader sequence, was 2 517 bp long with an open reading frame of 1 836 bp encoding 611 amino acid residues （GenBank accession No. EF583057）. The complete amino acid sequence of AChE deduced from the cDNA consisted of 21 residues for the putative signal peptide, and possessed a potential cleavage-addition site （ω） for a glycophosphatidylinositol anchor（GPI） at position 583 and 562 residues for the mature protein with a predicted molecular weight of 64 396.81 D. The conserved motifs involved in the catalytic triad, the choline binding sit and 12 aromatic residues lining the catalytic gorge were present in the Dd-ACE-1 deduced protein. The predicted protein shared with strong homology with Caenorhabditis elegans ACE-3 and C. elegans ACE-4. Phylogenetic analysis based on other nematodes and species AChEs showed that the deduced AChE formed a cluster with ACE-3s.