日本血吸虫一种新腺苷酸激酶全长cDNA的克隆与功能分析

目的：对用表达序列标签（Expression Sequence Tag,EST）策略从日本血吸虫尾蚴cDNA文库中筛选出的新基因进行功能预测。方法：用NCBI站点的BLASTx及BLASTn程序对所获得的新基因序列进行同源性搜索；用NCBI BLAST站点的blast two sequence程序对同源性高的基因进行核苷酸及氨基酸水平的同源性比较；利用Motif Scan in a Protein Sequence对cDNA序列所编码的蛋白质进行结构域搜索；利用CD－Search程序对目标蛋白进行保守区域搜索。结果：发现一个与曼氏血吸虫22kDa单核苷酸激酶mRNA高度同源的日本血吸虫新基因，基因与氨基酸水平的同一性均分别为86．0％和87．0％；蛋白结构域搜索及保守区域搜索结果显示，该cDNA序列所编码的蛋白质是一种腺苷酸激酶。结论：用EST策略筛选新基因是一个可行的方法，所筛到的日本血吸虫新基因编码一种腺苷酸激酶，全长编码序列与曼氏血吸虫腺苷酸激酶mRNA高度同源。

CLONING AND FUNCTION ANALYSIS OF THE FULL LENGTH SEQUENCE OF A NEW SCHISTOSOMA JAPONICUM ADENYLATE KINASE

Objective To analyse the function of the novel gene screened from the Schistosoma japonicum cercariae cDNA library by Expression Sequence Tag (EST) strategy. Methods The novel genes were searched for homologue identity with NCBI blast programme. The homologue of the two sequences with a high identity was compared on amino acid and nucleotide level with blast two sequence programme on NCBI BLAST site. The motifs of the protein coded by the novel gene were searched with Motif Scan in a protein sequence and CD search programme on ExPASy PROSITE. Results A novel cDNA sequence coding for a adenylate kinase was found from the cDNA library of Schistosoma japonicum cercariae, which is highly homologous to the known Schistosoma mansoni 22 kDa adenylate kinase mRNA. The identity of nucleiotide is 86 0%, while amino acid sequence is 87 0%. Conclusion EST strategy is effective for finding a novel gene. The novel gene codes for a nucleoside monophosphate kinase which is highly homologous to Schistosoma mansoni adenylate kinase mRNA.