刚地弓形虫热休克70基因编码蛋白结构与功能的生物信息学分析

Bioinformatics analysis of the structure and function of the gene encoding heat shock protein 70 from Toxoplasma gondii

目的分析并预测刚地弓形虫热休克蛋白70（TgHSP70）基因编码蛋白的结构与功能,探讨其作为疫苗候选抗原的可能性。方法从Genbank数据库获取TgHSP70基因序列,采用在线蛋白分析专家系统（http：//ca.expasy.org/）,结合DNAMAN等生物信息学软件对该序列的编码区进行分析,预测该基因编码蛋白质的理化性质、翻译后修饰位点、功能域、亚细胞定位、二级结构、亲/疏水性、三维空间结构、抗原表位等。结果该基因全长2 382 bp,编码区为143~2 146 bp。编码蛋白性质稳定,理论分子质量单位为72.304 97 ku。TgHSP70有6个跨膜区,为跨膜蛋白;有4个N端糖基化位点,6个蛋白激酶C磷酸化位点,14个酪氨酸激酶Ⅱ磷酸化位点,3个酪氨酸激酶磷酸化位点;无信号肽,二级结构以无规卷曲为主;TgHSP70主要存在于弓形虫速殖子胞液和核内,有26个潜在的抗原表位。结论 TgH-SP70基因编码蛋白为可溶性蛋白,有多个抗原表位,具有免疫原性,可作为弓形虫病疫苗候选抗原。

Objective To analyze and predict the structure and properties of the gene encoding protein of heat shock protein 70 from Toxoplasma gondii（TgHSP70）.Methods The gene sequence of TgHSP70 was obtained from the GenBank database and then tools on the ExPASy bioinformatics web site（http：//au.expasy.org/） were used to the gene.Tools were combined with other bioinformatics software such as DNAMAN to analyze the gene sequence.The physico-chemical properties of the coding protein,such as post-translational modification sites,functional domains,subcellular localization,secondary structure,hydrophilicity/hydrophobicity,tertiary structure,and epitopes,were predicted.Results The gene was 2 382 bp in length.Its coding region was 143 to 2 146 bp,coding for 667 amino acids,and was a complete and full-length coding region.The protein had stable physico-chemical characteristics.The theoretical molecular weight of the deduced protein was 72.3 ku.The coding protein was a transmembrane protein and was found to have six transmembrane domains and many post-translational modification sites including four N-terminal glycosylation sites,six protein kinase C phosphorylation sites,14 tyrosine kinase Ⅱ phosphorylation sites,and three tyrosine kinase phosphorylation sites but no signal peptides.There were six transmembrane domains in TgHSP70,a transmembrane protein.The secondary structure of TgHSP70 had many random coils.TgHSP70 was principally located in the cytosol and nucleus of T.gondii tachyzoites.There were 26 potential epitopes in the sequence of amino acids of TgHSP70.Conclusion Analytic results and predictions indicated that TgHSP70 is a soluble protein,it has many epitopes and immunogenicity,and it can be used as a candidate vaccine protein for toxoplasmosis.