Heterologous expression and purification of protopectinase-N from Bacillus subtilis in Pichia pastoris

A eukaryotic expression system for secretory production of the protopectinase from Bacillus subtilis XZ2 in Pichia Pastoris was constructed in this paper. The protopectinase gene without native signal sequence was amplified by PCR and fused to the pPICZαA plasmid containing α-factor sequence encoding secretion signal from Saccharomyces cerevisiae. The heterologous gene was expressed under the AOX1 promoter in a culture of P. pastoris X-33 in flasks. The recombinant protein was further purified by ammonium sulfate precipitate, Sephadex G75 and ion exchange chromatography and resulted in 18.91-fold purification; the purified protein was a molecular weight about 43 kDa and had an activity of 1948.64 U/mg.