Modification of the protein glycosylation pathway in the methylotrophic yeast Pichia pastoris

alpha-1,2-Mannosidase from Trichoderma reesei was used to modify the N-link ed glycosylation pathway of the methylotrophic yeast Pichia pastoris. Expre ssion of foreign influenza glycoproteins with more extensively processed N- linked oligosaccharides was observed when alpha-1,2-mannosidase was secrete d in the culture medium. However, intracellular removal of mannose residues may stimulate mannosyltransferase activity and leads to hyperglycosylation . [H-3]Mannose suicide selection or high concentrations of orthovanadate, c ommonly used to isolate glycosylation mutants of Saccharomyces cerevisiae, had no profound effect on Pichia pastoris.