Soluble Expression of IFNα2-Tα1 Fusion Protein in Escherichia coli by N-terminal SUMO Fusion and its Anti-Proliferative Activity

Interferon alpha 2 (IFN alpha-2) is a type of cytokine with both antiviral and anticancer activities. Binding of IFN alpha-2 to its receptor on cell surface leads to activation of interferon stimulated genes which mediate its anti-proliferative and anti-angiogenic properties. Similarly, Thymosin alpha 1 (T alpha-1) helps to fight against different infections such as cancer and hepatitis with its immune modulating properties as well as through its direct action on target cells. The recombinant expression of some proteins in E. coli produces inclusion bodies which are misfolded proteins. The objective of this study was soluble expression of IFN alpha 2-T alpha 1 fusion protein in E. coli using pET-SUMO vector and determination of its biological activity. SUMO-IFN alpha 2-T alpha 1 was successfully expressed in soluble form with IPTG induction to final concentration 0.5 mM at 37 degrees C for 4 h and purified using affinity chromatography. SUMO tag was removed from SUMO-IFN alpha 2-T alpha 1 by SUMO protease and recombinant IFN alpha 2-T alpha 1 was collected in flow through by affinity chromatography. The MW (similar to 23 kDa) of IFN alpha 2-T alpha 1 was determined by 12 % SDS-PAGE and its integrity was confirmed by Immuno blot analysis using anti-interferon alpha-2 and anti-thymosin alpha-1 antibodies. Purified IFN alpha 2-T alpha 1 demonstrated anti-proliferation activity as assessed by MTT assay. This study also showed that N-terminal fusion of SUMO with IFN alpha 2-T alpha 1 is effective for its soluble expression and to make its purification process more convenient.