无色书虱AChE基因克隆及其系统进化分析

Gene cloning of AChE and phylogenetic analysis in Liposcelis decolor

利用RT-PCR结合RACE技术克隆获得了无色书虱Ldace1的3′端序列和Ldace2的全长序列(GenBank登录号分别为:FJ647186和FJ647187)。其中Ldace2基因全长2111bp,ORF1917bp,编码638个氨基酸组成的前体蛋白,成熟蛋白的分子量为71.9kDa,理论等电点为4.70,序列比对表明该基因包括AChE家族的所有保守性功能位点;Ldace1基因仅获得了3′端1616bp的序列,编码500个氨基酸残基,序列比对发现,除缺少形成一对二硫键的半胱氨酸外,Ldace1包含了AChE家族的所有保守性功能位点。结合其它物种AChE构建的分子进化树可以看出,AChE分为4个类群:昆虫Ⅰ型AChE类群、脊椎动物AChE类群、昆虫Ⅱ型AChE类群和线虫AChE类群,其中无色书虱Ldace1和Ldace2分别属于昆虫Ⅰ型AChE类群和昆虫Ⅱ型AChE类群,且与嗜卷书虱和嗜虫书虱的AChE具有最近的进化关系。

The full length of Ld ace2 and partial fragment of Ld ace1 （GenBank accession number：FJ647187 and FJ647186） were cloned from Liposcelis decolor,respectively. The complete cDNA of Ld ace2 consists of 2111 bp with an ORF of 1917 bp,encoding a protein of 638 amino acids residues. The mature protein has a calculated molecular weight of 71.9 kDa with an isoelectric point of 4.7. All the typical residues of AChE family were found in the deduced amino acid sequence of Ld ace2 by sequence alignment. The fragment of Ld ace1 contains 1616 bp encoding 500 amino acid residues. The amino acid sequence has a high identity to AChE1 from L. bostrychophila and L. entomophila. It includes all the typical residues of AChE family except one conserved cysteine that composes disulfide bridge. The phylogenetic tree of 50 AChE amino acid sequences from 31 species were constructed by MEGA4.1. The results showed that all AChE genes were divided into four distinct main groups：Insect TypeⅠAChE Gene,Vertebrate AChE Gene,Insect TypeⅡAChE Gene and Nematode AChE Gene. Ld ace1 and Ld ace2 from L. decolor were classified into Insect TypeⅠAChE Gene and Insect TypeⅡAChE Gene,respectively.