Highly efficient production of peptides: N-glycosidase F for N-glycomics analysis

Peptide: N-glycosidase F (PNGase F) is an asparagine amidase produced by Flavobacterium meningosepticum that serves as a useful tool in the research on protein N-glycosylation. However, native PNGase F purified from F. meningosepticum and recombinant PNGase F expressed in Escherichia coli are obtained only at low levels, with the culture yield being no more than 15mg/L. Here, we report the efficient production of large amounts of recombinant PNGase F. First, a codon-optimized sequence encoding F. meningosepticum PNGase F was cloned into the pPICZaA vector, which was used to transform Pichia pastoris GS115. Clones were screened directly by dot blotting with an anti-6His-tag antibody, and then protein expression was induced in glass tubes to conduct validation assays. The clone expressing the highest level of PNGase F was selected for fermentation at a 5-L scale, and then the recombinant enzyme produced was purified in a single step using affinity chromatography, which yielded 800mg of the protein per liter of culture. The partly glycosylated recombinant PNGase F exhibited an identical specific activity as commercially available PNGase F when using RNase B or other N-glycoproteins as substrates. Thus, the method developed in this study can facilitate the large-scale production and use of PNGase F in the rapidly developing research field of N-glycomics.