低毒性金葡萄球菌肠毒素A D227A突变体的原核表达、纯化及鉴定

摘要

目的:获得低毒性但仍保留其免疫活性、高纯度的重组D227A突变型金葡菌肠毒素A蛋白(rSEAD227A).方法:利用PCR技术克隆含D227A突变的SEA基因并原核表达,用盐酸胍溶解包涵体并进行梯度透析复性;使用StrepⅡ亲和层析来纯化蛋白;免疫印迹和LC-MS/MS进行鉴定.结果:成功克隆SEA的D227A突变体,获得了高纯度的rSEAD227A蛋白. LC-MS/MS分析证实,胰酶消化后的rSEAD227A肽段序列与数据库中SEA的序列匹配.结论:获得了高纯度rSEAD227A蛋白,为SEA的进一步基础研究和临床应用提供了实验基础.%Objective:To obtain recombinant D227A mutation Staphylococcal enterotoxin A protein(rSEAD227A) with low toxicity but still retain its immunological activity and high purity. Methods: The SEA gene containing D227A mutation was cloned by PCR. By constructing pET44a-SEAD227Avector and transfecting the expression strain Rosetta, inclusion bodies were solubilized with guanidium hydrochloride and refolded by gradient dialysis;proteins were purified using StrepⅡ affinity chromatography,and identified by Western blot and high performance liquid chromatography-mass spectrometry(LC-MS/MS). Results: The D227A mutation of SEA was cloned and the expression system of Rosetta-rSEAD227Awas constructed. The purified rSEAD227Aprotein was obtained by refolding with gradient dialysis and affinity purification. LC-MS/MS analysis confirmed that the tryptic digested rSEAD227A peptide sequences matched the sequences of SEA in the database. Conclusion: The rSEAD227A protein in high purity was obtained,which provided the ex-perimental basis for further basic research and clinical application of SEA.