金黄色葡萄球菌SEG蛋白B细胞线性表位的预测与验证

Prediction and verification of the linear B-cell epitopes of staphylococcal enterotoxin G protein

以金黄色葡萄球菌标准株ATCC25923的肠毒素G蛋白(SEG)氨基酸序列为分析材料,应用DNAstar软件对该蛋白的二级结构、柔性区域、亲水性、表面可能性和抗原指数等参数进行综合分析,预测出SEG蛋白5个可能的B细胞线性表位,它们分别位于蛋白N端第24～31、37～46、80～84、120～127和141～149区域,且预测的表位2(aa 37～46)、表位4(aa120～127)和表位5(aa141～149)位于SEG蛋白三维结构表面。合成位于蛋白三维结构表面的3个预测表位,采用肽ELISA方法加以鉴定。结果表明,它们均能与抗重组SEG蛋白纯化抗体发生特异性结合反应,是SEG蛋白的B细胞线性表位。

In order to locate the B-cell linear epitopes of SEG protein, epitope prediction was performed using the amino acid sequence of SEG protein from Staphylococcus aureus standard strain ATCC25923. The secondary structure, flexible regions, hydrophilicity, surface accessibility and antigenic index of the protein were ana lyzed using the DNAStar Protean program, and five potential epitopes were screened, which were located at amino acid positions 24 to 31, 37 to 46, 80 to 84,120 to 127 and 141 to 149. Among them, the epitopes at amino acid positions 37 to 46, 120 to 127 and 141 to 149 were entirely exposed on the surface of the 3D structure model of SEG protein. To verify the prediction, three potential epitope peptides exposed on the surface of the 3D struc ture were artificially synthesized and detected by peptide-ELISA. The results showed that the three potential epi topes exposed on the surface of the 3D structure had a specific binding to purified antibodies against SEG protein. They were indeed B-cell linear epitopes of the SEG protein.