A novel self-cleavable tag Zbasic-ΔI-CM and its application in the soluble expression of recombinant human interleukin-15 in Escherichia coli

作者：Shi, Siwei; Chen, Huanhuan; Jiang, Hua; Xie, Yueqing; Zhang, Lei; Li, Ninghuan; Zhu, Chencen; Chen, Junsheng; Luo, Han; Wang, Jiaxian; Feng, Lei; Lu, Huili^*; Zhu, Jianwei^*

来源：Applied Microbiology and Biotechnology, 2017, 101(3): 1133-1142.

DOI：10.1007/s00253-016-7848-2

• Intein
• Zbasic
• Interleukin-15
• Soluble expression
• C-terminal cleavage

Soluble expression of recombinant therapeutic proteins in Escherichia coli (E. coli) has been a challenging task in biopharmaceutical development. In this study, a novel self-cleavable tag Zbasic-intein has been constructed for the soluble expression and purification of a recombinant cytokine, human interleukin-15 (IL-15). We screened several solubilizing tags fused with the self-cleavable Mycobacterium tuberculosis recA mini-intein Delta I-CM and demonstrated that Zbasic tag can significantly improve the solubility of the product with correspondent to the intein activity. The fusion protein "Zbasic-Delta I-CM-IL-15" was expressed with high solubility and easily enriched by the cost-effective cation-exchange chromatography. The self-cleavage of the fusion tag Zbasic-Delta I-CM was then induced by a pH shift, with an activation energy of 7.48 kcal/mol. The mature IL-15 with natural N-terminus was released and further purified by hydrophobic interaction and anion-exchange chromatography. High-resolution reverse-phase high-performance liquid chromatography and mass spectrometry analysis confirmed that the product was of high purity and correct mass. With a CTLL-2 cell proliferation-based assay, the EC50 was evaluated to be of about 0.126 ng/mL, similar to the product in clinical trials. By avoiding the time-consuming denaturing-refolding steps in previously reported processes, the current method is efficient and cost-effective. The novel tag Zbasic-Delta I-CM can be potentially applied to large-scale manufacturing of recombinant human cytokines as well as other mammalian-sourced proteins in E. coli.

• 出版日期2017-2
• 单位上海交通大学