Characterization of N- and O-linked galactosylated oligosaccharides from fission yeast species

The N- and O-linked oligosaccharides from fission yeast Schizosaccharomyces pombe not only contain large amounts of D-mannose (Man) but also contain large amounts of D-galactose (Gal). Although the galactomannans of S. pombe are mainly composed of alpha 1,2- or alpha 1,3-linked Gals, some of the terminal alpha 1,2-linked Gals are found to be linked to pyruvylated beta 1,3-linked galactose (PvGal). We have determined the structural characteristics of the N-glycans and O-glycans in three Schizosaccharomyces species (S. japonicus, S. octosporus, and S. cryophilus) using lectin blot, H-1 NMR spectroscopy, and size-fractionation high performance liquid chromatography (HPLC), and found that the galactosylation of oligosaccharides was a common feature in fission yeasts. In addition, each of the terminal Gala1,2-, Galb1,3- and non-substituted Man residues exhibited distinct characteristics. A BLAST search of gene databases in Schizosaccharomyces identified genes homologous to pvg1 encoding pyruvyltransferase of S. pombe. These genes, when expressed in an S. pombe pvg1 Delta strains, led to the pyruvylation of non-reducing terminal beta-linked Gal, suggesting the biosynthetic pathway of PvGal-containing oligosaccharides is highly conserved in fission yeasts. (C) 2020, The Society for Biotechnology, Japan. All rights reserved.