Biotechnology Bulletin ›› 2014, Vol. 0 ›› Issue (8): 182-188.

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Purification of GST-TRAF6 Fusion Proteins from Inculsion Body Expressed in E. coli

Zhang Xixuan, Li Ye, Zhang Zhenqi, Dong Shirui, Zhao Pei, Ruan Haihua   

  1. Tianjin Key Laboratory of Food Science&Biotechnology, College of Biotechnology&Food Science, Tianjin University of Commerce, Tianjin 300134
  • Revised:2014-01-23 Online:2014-08-15 Published:2014-08-01
  • Contact: 通讯作者: 阮海华,博士,副教授,研究方向:病原微生物与基因工程;E-mail:ruanhaihua@tjcu.edu.cn
  • Supported by:

    国家自然科学基金项目(81101220);天津市应用基础与前沿研究计划项目(12JCQNJC08100);“十二五”天津市中青年骨干创新人才支持计划,天津市教委高等学校科技发展基金计划项目(20130624)

Abstract:

There was only a minor fraction of GST-TRAF6 fusion proteins were observed soluble when expressed in E.coli. Most of the GST-TRAF6 fusion proteins were present in the inclusion body, in which the expressed proteins aggregate and exist in inactive. To obtain GST-TRAF6 fusion protein in a high yield and high purity, a method to purify the GST-TRAF6 fusion proteins from inclusion body without any loss of its bioactivity was constructed. Firstly, the inclusion body was denatured with 8 mol/L urea. Secondly, the GST-TRAF6 fusion protein in inclusion body were gradually solubilized by gradient dilution renaturation. Once the GST-TRAF6 fusion protein was fully dissolved in renaturation solution, it was conventional to purify the GST-TRAF6 fusion protein with glutathione sepharose 4B. The specificity and the bioactivity of the purified GST-TRAF6 fusion protein were testified by western blot and in vitro ubiquitination assay, respectively. The results indicated that GST-TRAF6 fusion protein were successfully solubilized by gradient dilution renaturation following the denaturation of 8 mol/L urea, the concentration of the purified GST-TRAF6 fusion protein was achieved a concentration of 396 ng/μL with a purity over 90%. The specificity of this GST-TRAF6 fusion proteins were identified with anti-GST western blot. In vitro ubiquitination assay indicated that the GST-TRAF6 fusion protein in a concentration of 17 ng/μL could rapidly catalyze the formation of free ubiquitin chains within 5 minutes. In conclusion, it was found that the GST-TRAF6 fusion protein could be successfully renatured with the method of gradient dilution renaturation with the recovery of its capability of ubiquitin ligase. This results would supply a useful method for the large-scale purification of proteins from inclusion body when expressed in E. coli.

Key words: TRAF6, Protein purification, Inclusion body renaturation, Recombinant protein