Expression of Goose Interleukin 2 in Escherichia coli and Isolation of Its Soluble Monomer

Recombinant expression plasmid of pET-28a(+)-goIL-2 was constructed by inserting goose IL-2 gene without signal peptide sequence into a prokaryotic expression vector pET-28a(+), and transformed into E. coli BL21(DE3) cells for expression. After IPTG induction, an expected protein band with molecular weight of 15.0 kD was observed on SDS-PAGE gel, recognized by monoclonal antibody against goose IL-2 in Western blotting analysis. In the pET-28a(+) expression system, the recombinant goose IL-2(rgoIL-2) was mainly found in inclusion bodies with a portion of soluble protein. The monomer and multimers of soluble goose interleukin 2 protein were observed in native electrophoresis. The rgoIL-2 protein was purified by Ni-NTA column under native condition. The rgoIL-2 soluble protein monomer was isolated by a quick protein isolation and purification system of ÄKTA FPLC and identified by native PAGE. Bioactivity analysis showed that the rgoIL-2 monomer stimulated the proliferation of goose lymphocytes in vitro. It provides a basis for studying the biological function of goose IL-2 as well as its clinical application.