刚地弓形虫钙网蛋白的生物信息学分析

Bioinformatics analysis of Toxoplasma gondii calcinetin

目的应用生物信息学方法预测刚地弓形虫钙网蛋白(oxoplasma gondii calreticulin,TgCRT)的结构特点、免疫原性及抗原性。方法利用ProtParam、ProtScale和SignaIP软件分别预测TgCRT的理化参数、亲/疏水性和信号肽;利用Colis、TMHMM和KinasePhos3.1预测其卷曲螺旋、跨膜结构域及磷酸化位点;利用SOPMA和Phyre2预测其二、三级结构,利用DNAstar分析表面可及性等参数;利用ABCpred、Syfpeithi和DNAstar预测其B、T细胞表位。结果TgCRT蛋白含578个氨基酸,相对分子质量为64.18607×10^(3),分子式为C_(2841)H_(4519)N_(801)O_(857)S_(18),理论等电点(pI)为5.69。不稳定系数55.50,疏水值85.45,总平均亲水性指数-0.321,属于不稳定亲水性蛋白;该蛋白无信号肽有跨膜区,含44个磷酸化位点,其中31个丝氨酸磷酸化位点,11个苏氨酸磷酸化位点,2个酪氨酸磷酸化位点。1个部位形成卷曲螺旋,二级结构中α-螺旋、β-折叠分别占42.21%、11.42%,β-转角、无规则卷曲分别占3.81%、42.56%;沿肽链走向均匀分布柔韧性、亲水性、表面可及性高分区段;有23个B细胞抗原表位,21个限制性CTL细胞表位和10个限制性Th细胞表位。结论TgCRT蛋白含有多个潜在的的B、T细胞表位,具有免疫原性和抗原性,可作为抗弓形虫感染疫苗候选蛋白。

Objective Bioinformatics method was used to predict the structural characteristics,immunogenicity and antigenicity of Toxoplasma gondii calreticulin(TgCRT).Methods The physical and chemical parameters,hydrophilic/hydrophobic properties and signal peptides of TgCRT were predicted by ProtParam,ProtScale and SignaIP;Colis,TMHMM and KinasePhos3.1 were used to predict the coiled coil,transmembrane domain and phosphorylation sites;SOPMA and Phyre2 were used to predict the secondary and tertiary structures,DNAStar was used to analyze parameters such as surface accessibility;ABCpred,Syfpeithi and DNAStar were used to predict B and T cell epitopes.Results TgCRT protein contained 578 amino acids with a relative molecular weight of 64.18607×10~3,a molecular formula of C_(2841)H_(4519)N_(801)O_(857)S_(18),a theoretical isoelectric point(pI)of 5.69.The instability index was 55.50,the hydrophobic value was 85.45,and the total average hydrophilicity index was-0.321,which certificated TgCRT was unstable and hydrophilic protein.Meanwhile,it was a transmembrane protein without signal peptide and contained 44 phosphorylation sites,including 31 serine phosphorylation sites,11 threonine phosphorylation sites and 2 tyrosine phosphorylation sites.One site formed a coiled coil region;In the secondary structure,alpha helices and beta folds accounted for 42.21%and 11.42%respectively,beta turns and random colis accounted for 3.81%and 42.56%,respectively.High-grade sections of flexibility,hydrophilicity and surface accessibility were evenly distributed along the peptide chain.There were 23 B cell antigen epitopes,21 restricted CTL cell epitopes and 10 restricted Th cell epitopes.Conclusion TgCRT protein contains multiple potential B and T cell epitopes with immunogenicity and antigenicity,and can be used as a candidate protein for vaccine against Toxoplasma gondii infection.