High Performance Secreted Expression of Porcine Interferon Alpha Gene in Pichia pastoris by Codon Change

According to the codon metatropism of Pichia pastoris,the porcine interferon alpha(PoIFN-α) gene,in which the sequence encoding signal peptide was replaced by that of the α-factor of Saccharomyces cerevisiae,was cloned into P.pastoris expression vector pPICZαC.The recombinant plasmid pPICZαC-PoIFN-α was then transformed into P.pastoris X-33 cells by electroporation,and stable multicopy recombinant P.pastoris strains were selected by ZeocinTM resistance.A great quantity of multiple-inserted recombinants were obtained.SDS-PAGE and Western-blot assays of culture broth from a methanol-induced expression strain demonstrated that recombinant PoIFN-α,about 19 000 proteins,were secreted into the culture medium at the concentration of 54.105 mg/L.The potency of PoIFN-α was up to 5.87×107 U/L by Vero-VSV systems measurement.This experiment changed the sequence coding of PoIFN-α by the codon metatropism of P.pastoris and the results proved that this change was feasible.