Characterization of N-linked oligosaccharides assembled on secretory recombinant glucose oxidase and cell wall mannoproteins from the methylotrophic yeast Hansenula ploymorpha

Abstract

Presently almost no information is available on the oligosaccharide structure of the glycoproteins secreted from the methylotrophic yeast Hansenula polymorpha, a promising host for the production of recombinant proteins. In this study, we analyze the size distribution and structure of N-linked oligosaccharides attached to the recombinant glycoprotein glucose oxidase (GOD) and the cell wall manno-proteins obtained from H. polymorpha. Oligosaccharide profiling showed that the major oligosaccharide species derived from the H. polymorpha-secreted recombinant GOD (rGOD) had core-type structures (Man8-12GlcNAc2. Analyses using anti-α1,3-mannose antibody and exoglycosidases specific for α1,2- or ,6-mannose linkages revealed that the mannose outer chains of N-glycans on the rGOD have very short α1,6 extensions and are mainly elongated in α1,2-linkages without a terminal α1,3-linked mannose addition. The N-glycans released from the H. polymorpha mannoproteins were shown to contain mostly mannose in their outer chains, which displayed almost identical size distribution and structure to those of H. polymorpha-derived rGOD. These results strongly indicate that the outer chain processing of N-glycans by H. polymorpha significantly differs from that by Saccharomyces cerevisiae, thus generating much shorter mannose outer chains devoid of terminal α1,3-linked mannoses.