日本血吸虫鸟氨酸转氨酶基因的获得和分析

目的运用表达序列标签(expressedsequencetag,EST)技术,从日本血吸虫成虫cDNA文库中筛选和鉴定日本血吸虫新基因鸟氨酸转氨酶。方法转化日本血吸虫成虫cDNA文库,随机挑取重组阳性克隆进行测序,获得EST;用NCBI站点的GenBank对所获得的新基因序列进行同源性检索;利用BLAST程序对同源性高的基因进行核苷酸和氨基酸水平的同源性比较;并利用pc-gene软件对其蛋白质结构进行初步分析。结果获得了1个日本血吸虫新基因鸟氨酸转氨酶基因(GenBank登录号AY336497)。该cDNA序列长1677bp,编码424个氨基酸,与Xenopuslaevis鸟氨酸转氨酶同源性为66%;编码蛋白的理论等电点为8.52;抗原表位可能位于cDNA序列795～846处。结论用EST寻找日本血吸虫新基因是一种可行的方法,所筛选到的日本血吸虫新基因与Xenopuslaevis鸟氨酸转氨酶基因同源,为进一步研究该基因的全序列及功能作准备。

Acquiring and analyzing of ornithine aminotransferase gene of Schistosoma japonicum

Objective To screen and identify the novel genes from the adult worm cDNA library of Schistosoma japonicum by the expressed sequence tags (EST) strategy.Methods The cDNA clones were selected randomly and the ESTs were obtained.The novel gene was searched for homologue identity with NCBI blast programmer.The homologue of the two sequences with a high identity was compared at amino acid and nucleotide level with the BLAST programmer,and the analysis of protein was carried out with the pcgene software. Results There was a novel gene of Schistosoma japonicum which included 1 677 bp coding for 424 amino acid residues, and it was given the accession number of sequence in Genbank(AY336497).The cDNA sequence was homologous to the known ornithine aminotransferase gene of Xenopus laevis. The identity of amino acid sequence was 66%. The academic pI was 8.52, and the antigen determinant was probably from 795 to 846 on the cDNA sequence. Conclusion EST strategy is an effective measure to discover new genes of Schistosoma japonicum. The novel gene is homologous to the ornithine aminotransferase gene of Xenopus laevis.This study is helpful to further sequential and functional search of the gene.