日本血吸虫小蛋白型多药物/代谢物排出蛋白样基因(SMR-like)的发掘和生物信息学分析

目的日本血吸虫可能的多药物抗性基因的发掘和所编码的蛋白的结构、功能以及应用前景分析。方法利用美国国家生物技术信息中心（NCBI,http：//www.ncbi.nlm.nih.gov/）的在线分析工具BLASTx和瑞士生物信息学研究所的蛋白分析专家系统（ExPaSy,http：//ca.expasy.org/）和CBS Prediction Servers提供的蛋白序列在线分析工具,结合Vector NTI suite生物信息学分析软件,以华支睾吸虫小蛋白多药物抗性基因（smr）为“饵”,从GenBank日本血吸虫基因数据库中发掘出其同源基因,预测蛋白的结构和功能特征,并分析其应用前景。结果从GenBank中找到了一个功能未知的日本血吸虫同源基因AY813157,氨基酸序列与华支睾吸虫smr蛋白的一致性达67%,相似性达80%;该基因含有一个完整的编码区,编码189个氨基酸;预测氨基酸序列具有主要协助因子超家族的结构特征,含有5段跨膜区,其中3段跨膜区中含有保守的精氨酸和组氨酸残基,有多个磷酸化位点和T、B细胞表位。拓扑学分析表明N端在胞内,C端在胞外,线性B细胞表位均位于胞外区。结论日本血吸虫AY813157基因可能编码一个小蛋白型多药物/代谢物排出蛋白,与阴离子型药物（如吡喹酮）的抗药性或有毒性的阴离子代谢物的排出有关;该蛋白可能定位于皮层的表膜,是一个日本血吸虫免疫诊断和疫苗的候选靶分子,在研究日本血吸虫的耐药机制及免疫诊断和疫苗方面较好的应用前景。

Uncovering and Bioinformatics Analysis of Schistosoma japonicum Small Multidrug/Metabolites Efflux Protein-Like Gene

Objective To uncover the probable multidrug-resistance gene and analyze the structural and functional characteristics of the putative protein and its potential applying prospects. Methods Utilize the on-line tools provided by the bioinformatics websites such as NCBI(http://www.ncbi.nlm.nih.gov/),ExPaSy (http://www.ncbi.nlm.nih.gov/),and CBS Prediction Servers (http://www.cbs.dtu.dk/services/) and incorporate Vector NTI suite 8.0 software package to pick out the Schistosoma japonicum homologue of a newly cloned Clonorchis sinensis small multidrug /metabolites efflux protein-like gene by BLASTx,and predict the characteristics of the structure,function and immunology of the deduced amino acid sequence. Results A Schistosoma japonicum homologue in GenBank with access number AY813157 was uncovered. The gene contains a complete cds which encoding 189 amino acids with the identity of 67% and similarity of 80% to the Clonorchis sinensis smr-like gene.The interPro Scan program predict it belong to the subfamily of MFS-1 of the Major Facility Superfamily with the property of small multidrug/metabolites efflux 1protein,which contains four or five transmembrane regions. The N terminus is inside of the membrane with the C terminus outside. Three of five transmembrane regions contain a conserved basic amino acid residue arginine or histidine and there are several phosphorylation sites and T cell epitopes and linear B cell epitopes which mainly located in the outside of membrane. Conclusion The Schistosoma japonicum gene which is designated the access number AY813157 encodes the small multidrug/metabolites efflux protein homologue which maybe involved in the pump-out of anionic drugs or deleterious metabolites. The protein probably located in the membrane of tegument of Schistosoma japonicum which may be a candidate of vaccine and immunodiagnosis with promising prospects in mechanisms study of drug-resistance (such as praziquantel)and in development of immunodiagnosis kits and vaccine for schsistomiasis.