肠毒素C2中Met24对其超抗原活性无重要作用  

Functional Roles of Residue Methionine at Position 24 in Staphylococcal enterotoxin C2

作　　者：王洪波[1,2] 李洪义[3] 孙健[1] 张惠文[1] 徐明恺[1] 

机构地区：[1]中国科学院沈阳应用生态研究所,辽宁沈阳110016 [2]中国科学院研究生院,北京100049 [3]沈阳协合生物制药股份有限公司,辽宁沈阳110179

出　　处：《生物技术》2011年第4期67-70,共4页Biotechnology

基　　金：国家科技重大专项重大新药创制项目(2009ZX09103-692)资助

摘　　要：目的:分析金黄色葡萄球菌肠毒素C2的T细胞受体结合区域α3结构中,第24位甲硫氨酸对其超抗原活性的影响作用。方法:应用定点突变技术对金黄色葡萄球菌肠毒素C2的Met24进行无意义突变,获得突变蛋白SEC2(M24A),对突变蛋白和野生型蛋白的体内、体外超抗原活性进行比较。结果:分别对野生型蛋白及突变蛋白的免疫刺激活性、肿瘤抑制活性、体内致热毒性进行了比较,发现突变蛋白的增值指数(PI)、抑瘤率、热源效应与野生型相比无显著差异(P>0.05),这表明对第24位甲硫氨酸的替换没有对金黄色葡萄球菌肠毒素C2的超抗原活性造成明显影响。结论:在金黄色葡萄球菌肠毒素C2的α3结构中,Met24并不是决定其超抗原活性的重要氨基酸残基。Objective：The purpose of this study is to determine the key amino acid participating in the binding with T cell receptor in the α3 domain of Staphylococcal enterotoxin C2.Method：According to the crystal study,the Met at position 24 of Staphylococcal enterotoxin C2（SEC2） was likely to participate in the binding with T cell receptor directly,so it was selected as target in this research.Over-lap PCR was employed to construct mutant protein SEC2（M24A） gene.The mutant protein SEC2（M24A） was expressed by E.coli BL21（DE3） and purified by affinity chromatography.The bioactivities of mutant SEC2 and the native were compared both in vivo and in vitro.Result：The experimental data indicated that the immunostimulatory activity and tumor cell growth inhibition effect of the mutant protein were not affected by the amino acid substitution.Further more the pyrogenic effect of SEC2（M24A） was similar with that of the native SEC2.The amino acid substitution introduced at position 24 has not significantly changed the superantigen activities of SEC2.Conclusion：The results above explained that although the residue Met at position 24 located in the α3 domain,it was not a key amino acid involved into the contact with T cell receptor.

关 键 词：金黄色葡萄球菌肠毒素C2 定点突变 T细胞受体 

分 类 号：Q71[生物学—分子生物学]