[Construction of expression vectors for efficient expression of soluble recombinant proteins]

The aim of the study is to construct two vectors for efficient expression of soluble recombinant proteins. The first vector was constructed by cloning the HisSUMO fragment into an expression vector pET30a(+) to fuse with the gene of interest (designated as HisSUMO Express). The second vector was constructed in the same way, but with a hydroxylamine cleavage site between HisSUMO and the gene of interest for an economic purpose (designated as HisSUMO Economic). The mouse fibroblast growth factor-21(mFGF-21), which was difficult to express in routine-used expression vectors, was taken as an example to test the vectors. The results showed that the mFGF-21 was expressed at high level in both vectors. The Sumo/mFGF-21 fusion protein accounted for more than 40% of the total bacterial protein. The fusion protein was purified with Ni-TNA column, and the HisSUMO was removed by cleavage of the fusion protein with either hydroxylamine solution or SUMO protease I. The concentration of the purified mFGF-21 mature protein was 54 mg/L and the recovery rate was 6%. The purified proteins derived from either hydroxylamine or SUMO protease I cleavage could stimulate glucose up-take by adipocytes. These results indicated that both HisSUMO Express and HisSUMO Economic were useful expression vectors for efficient expression of soluble recombinant proteins.