Expression Of Bovine Interleukin-2 Gene In Pichia Pastoris

Interleukin-2 (IL-2) is a cytokine secreted by activated T lymphocytes and has an important role in a number of in vivo immune responses. The important function of IL2 is to induce T cell proliferation and differentiation and to promote helper T cells and NK cells to product cytokines. Therefore, recombinant BoIL2 is desirable as immunoadjuvant and immunotherapy agent. In this study, recombinant BoIL2 was expressed successfully in Pichia pastoris.The methylotrophic yeast Pichia pastoris has been developed as an efficient expression system for foreign proteins. It can grow on methanol as a sole carbon and energy source. As a eukaryotic expression system. Pichia pastoris has many advantages over prokaryotes and other higher eukaryotes. It is as easy to manipulate and culture as prokaryotes and is able to process posttranslational modifications as other higher eukaryotes.In this study, the BoIL2 gene cDNA was cloned into the Pichia pastoris expression vector of pPICZB, which is under the control of the alcohol oxidase promoter AOX1. The linearnized recombinant plasmid of pPICZB-BoIL2, digested by Sac I , was transformed into X-33 strains by electroporation. The multi-copy insert transformants were screened by Zeocin-resistance screening and induced by 1% methanol .The intracellular soluble expression products were detected by SDS-PAGE analysis and western blotting analysis. Purified recombinant BoIL2 protein with His-Tag was obtained by metal-chelating affinity chromatography (MCAC). Assay with murine CTLL-2 cells showed that the recombinant BoIL2 exhibited the biological activity to induce T cell proliferation.