日本血吸虫新基因—腺苷酸激酶基因的发现与克隆

目的：将用表达序列标签（expression sequence tag,EST)策略及同源性搜索发现的日本血吸虫新基因－腺苷酸激酶（adenylate kinase,AK)cDNA克隆到表达质粒，pET32a( )上，为下一步研究该基因的功能做准备，方法：将插入于pTriplEx2质粒上的cDNA进行,测序，用BLASTn程序搜索测序结果，根据表达质粒pET32a( )上的克隆位点及该cDNA序列设计PCR引物，将PCR产物纯化后连接到pMD 18-T载体上，将重组T载体经EcoR I/Xho I双酶切后切下的SjAK基因导入原核一表达质粒pET32a( )中，结果：本研究所发现的新基因与曼氏血吸虫AK基因的同一性达86％，PCR产物的片段长度与预期大小一致，重组T载体及表达质粒经EcoR I及Xho I双酶切后有具有与目标片段工度相符的插入片段，结论：发现日本血吸虫的cDNA与曼氏血吸虫AKcDNA高度同源，并且成功地构建出重组表达质粒pET32a( )-SjAK。

Identification and cloning of adenylate kinase gene, a novel gene of Schistosoma japonicum]

OBJECTIVE: To subclone a novel gene of Schistosoma japonicum (Sj), adenylate kinase (AK) cDNA, which was identified through expressed sequence tag (EST) strategy and homology search, so as to prepare for further functional study of this gene. METHOD: The inserted cDNA fragment was sequenced and searched with BLASTn program. Two PCR primers were designed according to the sequence of this Sj AK cDNA and the cloning sites in pET32a (+) plasmid, with the product purified before linkage with pMD 18-T vector. The recombinant T-vector was digested with EcoRI /XhoI to obtain Sj AK cDNA, which was then introduced into the expression plasmid pET32a (+). RESULTS: The novel gene possessed 86% homology with Sm AK cDNA, and the PCR product is of expected length. Double digestion with EcoR I and Xho I proved that the recombinant T-vector and the expression plasmid had the insert with length identical to that of the target fragment. CONCLUSION: The novel cDNA codes for adenylate kinase of Schistosoma japonicum, and the recombinant expression plasmid pET32a (+)-Sj AK have been successfully constructed.