Abstract: The human tumor necrosis factor type 1 receptor (hTNFR1) gene was cloned into pET-22b expression vector, this study successfully constructed the recombinant plasmid pETH1 and transformed it into Escherichia coli BL21 (DE3) expression strain for shake flask fermentation, realizing heterologous expression of hTNFR1 in E. coli. However, all the proteins were in the forms of inclusion bodies. To improve the soluble expression of the target protein existed in the sedimentation in E. coli, we used two strategies of fusion tagging and molecular chaperone for protein folding. Results showed that, the fusion of NusA to the N-terminus of hTNFR1 increased the solubility; based on NusA-hTNFR1, seven molecular chaperones was overexpressed, among which the molecular chaperone tig was screened for it showed significant promotion on the soluble expression of hTNFR1 in E. coli; we purified protein by Ni-NTA affinity chromatography, then, the tig of NusA in the N-terminus of hTNFR1 was removed by enzymatic hydrolysis with TEV protease. After identification by Western blot, the hTNFR1 protein with high purity was obtained. The results laid a good foundation for further study on the physiological activity of hTNFR1 as well as the treatment of diseases.

Key words: hTNFR1, E. coli, NusA tag, tig molecular chaperone, protein purification

摘要： 将人源肿瘤坏死因子Ⅰ型受体（hTNFR1）基因克隆到pET-22b表达载体,成功构建了重组表达质粒pETH1，电转到Escherichia coli BL21（DE3）表达菌株中进行摇瓶发酵。实现了hTNFR1在大肠杆菌表达系统中的重组表达。但目的蛋白全部以包涵体的形式存在于沉淀中。为了提高hTNFR1在大肠杆菌中的可溶性表达，融合标签和分子伴侣两种策略被实施用于辅助hTNFR1的可溶性表达。结果表明，在hTNFR1的N端融合NusA标签后，hTNFR1的可溶性有一定提高；在NusA-hTNFR1基础上，过表达了7种分子伴侣，筛选出tig分子伴侣对hTNFR1蛋白可溶性表达有明显的促进作用，可溶性表达量约占总量的90％；对优化后的hTNFR1表达系统的可溶性蛋白进行Ni-NTA亲和层析纯化后，TEV蛋白酶酶切去除N端的NusA标签，结合Western blot分析鉴定，获得了大量高纯度的hTNFR1蛋白。研究结果为进一步研究hTNFR1的生理学活性及其在疾病治疗方面的应用奠定了良好基础。

关键词: hTNFR1, 大肠杆菌, NusA标签, tig分子伴侣, 蛋白纯化