Eukaryotic expression, purification and activity characterization of human soluble DSG2 extracellular domain protein.

Objective: To construct a secretory eukaryotic expression vector of DSG2 fused with the Fc region of the human IgG, to validate its expression in 293T cells, and to purify the secretory protein with biological activity. Methods: The DSG2 extracellular domain fragment gene (DSG2ex), was amplified by PCR, and was inserted into the eukaryotic expression plasmid pCMV3-IgG1 to construct the recombinant eukaryotic expression plasmid-pCMV3-DSG2ex-IgG1. The successfully constructed eukaryotic expression plasmid was transfected into 293T cells to express and secrete DSG2 extracellular domain protein. The targeted protein was purified from the cell culture supernatant by Protein A affinity chromatography and confirmed by Western Blotting and ELISA. Results: The pCMV3-DSG2ex-IgG1 eukaryotic expression plasmid was successfully constructed. The highest protein expression level was obtained with 293T cells after 96 h of transfection. The relative molecular mass of the purified product was between 100 and 130 kDa estimated by SDS-PAGE, which was consistent with the expectation. The yield of the purified protein reached 0.8 mg/mL with a purity over 90%. The purified DSG2 extracellular domain protein with IgG1 tag was recognized by IgG monoclonal antibodies by Western blotting. Moreover, the ELISA results showed that the prepared DSG2 extracellular domain protein had significant binding activity to human type 55 adenovirus Fiber Knob protein (HAdV-55).Conclusion: A simple and efficient method for eukaryotic expression and purification of human soluble DSG2 extracellular domain protein was successfully established, and biologically active DSG2 extracellular domain protein was purified, which laid the foundation for the later study of its protein function and anti-adenovirus drugs. [ABSTRACT FROM AUTHOR]