【摘要】 目的探讨微小隐孢子虫（Cryptosporidium parvum）Iowa Ⅱ株亲环素（CyPs）家族蛋白与微小隐孢子虫感染、致病、生存及与宿主免疫调控之间的关系。方法利用生物信息学工具,获取微小隐孢子虫Iowa Ⅱ株Cy Ps家族蛋白的序列信息,然后进行结构域预测、重要氨基酸位点的分析、motif搜索、蛋白的理化性质分析、信号肽预测和跨膜区预测,最后对不同物种的CyPs进行多重比对与进化树分析,并结合Blast-P同源比对和文献分析结果进行C.parvum Iowa Ⅱ株CyPs家族蛋白的功能预测。结果搜索到了C.parvum基因组中7个含有cyclophilin superfamily典型结构域的CyPs编码基因,分别是cgd1₈70、cgd2₁660、cgd2₄120、cgd5₃350、cgd7₅20、cgd8₁560和cgd8₂350。通过功能预测发现,cgd1₈70的N端含有信号肽,是一个典型的分泌型肽酰脯氨酸顺反异构酶（PPIase）,很有可能是隐孢子虫和宿主相互作用的重要分子基础;cgd2₁660属于Cyclophilin_PPIL3_like亚家族,缺乏环孢菌素A（CsA）结合需要的关键氨基酸残基,无法结合CsA发挥免疫抑制作用;cgd2₄120属于cyclophilin_ABH_like亚家族,且含有CsA_PPIase₁ motif,在隐孢子虫细胞内可以作为CsA的胞内受体发挥着对隐孢子虫的免疫抑制作用;cgd7₅20不仅具有CyPs家族的典型功能而且还具有WD40家族蛋白的相关功能,可能在隐孢子虫的生存过程中发挥着重要的作用;cgd8₂350还含有一个RRM结构域,不仅具备亲环素家族典型的PPIase活性,并且能够结合核酸参与基因表达过程的各种RNA加工过程,是一个对基因转录后水平有重要影响的蛋白。结论隐孢子虫基因组中存在7种CyPs的编码基因,其特征与功能均存在异同,其中cgd1₈70具有分泌型的信号肽,是一个分泌性蛋白。更多还原

【Abstract】 Objective The purpose of this study was to discuss the relationship between the cyclophilin family proteins（CyPs） of Cryptosporidium parvum（C.parvum） Iowa Ⅱ and the infection,virulence,survival and host immune regulation of the C.parvum. Methods The sequence information of CyPs of C.parvum Iowa Ⅱ were obtained by the bioinformatics tools,and then the domain prediction and crucial residues analysis,the motifs search and the protein physical and chemical properties analysis,and the signal peptide and transmembrane domain structure prediction were all analysed by the bioinformatics tools. Finally,the function of the CyPs of the C.parvum Iowa Ⅱ was predicted by the multiple alignment and phylogenetic tree analysis combined with the Blast-P homology and literatures search. Results 7 CyPs encoding genes which all contain cyclophilin superfamily domain were obtained;they are cgd1₈70,cgd2₁660,cgd2₄120,cgd5₃350,cgd7₅20,cgd8₁560 and cgd8₂350. From the function prediction,it was found that the cgd1₈70 may be a typical secreted peptidyl-prolyl cis-trans isomerase（PPIase） and is likely to be an important molecule for the interaction between C.parvum and host. The cgd2₁660 belongs to the Cyclophilin_PPIL3_like subfamily,lacking the key amino acid residues needed for cyclosporin A（CsA）binding,so it may not be able to bind to CsA to show an immunosuppressive effect. The cgd2₄120 belongs to the cyclophilin_ABH_like subfamily and contains CsA_PPIase₁ motif,which may act as an intracellular receptor for CsA in Cryptosporidium cells to play an immunosuppressive effect against the C.parvum. The cgd7₅20 not only has the typical function of the CyPs family but also has the related function of the WD40 family protein and may play an important role in the survival process of Cryptosporidium. The cgd8₂350 also contains an RRM domain that is not only has the typical PPIase activity of the cyclophilin family,but also can bind to the nucleic acid to participate in theRNA processing involved in the gene expression process,so it may has a significant effect on post-transcriptional levels of thegene. Conclusion There are 7 CyPs′ encoding genes presented in the genome of Cryptosporidium,which all havesimilarities and differences in their features and functions. Among them,only the cgd1₈70 has a secreted signal peptide,asecretory protein,which is likely to be a potential molecular basis for the interaction between Cryptosporidium and the hostimmune system.更多还原