[Secreted expression of porcine interferon-gamma gene in Pichia pastoris].

The porcine interferon-gamma(PoIFN-γ) gene, in which the sequence encoding signal peptide was replaced by that of the α-factor of Saccharomyces cerevisiae, was cloned into Pichia pastoris expression vector pPIC9K. The recombinant plasmid pPIC9K-α-PoIFN-γ was then transformed into Pichia pastoris GS115 cells by electroporation and stable multicopy recombinant Pichia pastoris strains were selected by G418 resistance. Two recombinants of multiple inserts were obtained. SDS-PAGE and Western blot assays of culture broth from a methanol-induced expression strain demonstrated that recombinant PoIFN-γ, 17kD and 23kD proteins, were secreted into the culture medium. Target proteins, 60% of total proteins, were obtained in the culture medium at the concentration of 108mg/L. This is the first secreted expression of porcine interferon-gamma gene in Pichia pastoris.