痢疾福氏2a asd基因的克隆及其序列分析

Cloning and sequencing of Shigella flexneri 2a asd gene

本文根据大肠杆菌 (E .coli)K12asd基因两侧序列设计了一对引物 ,用全菌PCR扩增了福氏 2aT32株的asd基因及其两侧序列。对PCR产物的初步测序结果表明 ,在asd基因两端存在BamHI位点。为了防止由PCR扩增带来的差错 ,我们又从福氏 2aT32株染色体中克隆了全长的asd基因。序列分析的结果表明 ,福氏 2aT32株asd基因的序列与E .coliK12的完全一致 ,全长 16 80bp ,其两侧序列也与E .coli具有高度的同源性。这为以asd基因作为靶基因构建痢疾菌的载体宿主平衡致死系统创造了条件。

On the basis of the flanking sequences of E.coli K 12 strain asd gene,a pair of primers were designed.With them the asd gene of S.flexneri 2a T32 strain and its flanking sequences were obtained by whole cell PCR.In order to prevent errors from PCR,the asd gene of S.flexneri 2a T32 strain was cloned from its chromosome according to the preliminary sequencing results of PCR products.The result of DNA sequencing indicated that the asd nucleotide sequence of S.flexneri 2a T32 strain consists of 1680 bp,is the same as E.coli K 12,and that their flanking sequences were highly homologous.This will be of benefit to constructing the balanced lethal system of Shigella.