A Combined System for Engineering Glycosylation Efficiency and Glycan Structure in Saccharomyces cerevisiae

Abstract

ABSTRACT We describe a novel synthetic N-glycosylation pathway to produce recombinant proteins carrying human-like N-glycans in Saccharomyces cerevisiae , at the same time addressing glycoform and glycosylation efficiency. The Δ alg3 Δ alg11 double mutant strain, in which the N-glycans are not matured to their native high-mannose structure, was used. In this mutant strain, lipid-linked Man 3 GlcNAc 2 is built up on the cytoplasmic side of the endoplasmic reticulum, flipped by an artificial flippase into the ER lumen, and then transferred with high efficiency to the nascent polypeptide by a protozoan oligosaccharyltransferase. Protein-bound Man 3 GlcNAc 2 serves directly as a substrate for Golgi apparatus-targeted human N-acetylglucosaminyltransferases I and II. Our results confirmed the presence of the complex human-like N-glycan structure GlcNAc 2 Man 3 GlcNAc 2 on the secreted monoclonal antibody HyHEL-10. However, due to the interference of Golgi apparatus-localized mannosyltransferases, heterogeneity of N-linked glycans was observed.