Two types of galactosylated fucose motifs are present on N-glycans of Haemonchus contortus

Abstract

N-Glycans from the nematode Haemonchus contortus (barber pole worm), a parasite of sheep and cattle, were the first to be described to possess up to three fucose residues associated with the N,N'-diacetylchitobiosyl core, two being on the reducing-terminal proximal GlcNAc and one on the distal core GlcNAc residue. The assumption was that truncated glycans from this organism with three hexose residues have the composition Man3GlcNAc2Fuc1-3. In this study, we have performed HPLC and MALDI-TOF MS/MS in combination with selected digestions of N-glycans from Haemonchus. A dominant trifucosylated Hex3HexNAc2Fuc3 glycan was modified not only with α1,6-fucose but also with a proximal core α1,3-fucose and a galactosylated distal α1,3-fucose; thereby, only two of the hexose residues were mannose. Other N-glycans displayed galactosylation of the core α1,6-fucose, antennal fucosylation or modification with phosphorylcholine. Thus, the N-glycans of Haemonchus contain a number of potentially immunogenic glycan epitopes also found in other parasites and our proposed structures are in line with the previously defined specificity of nematode glycosyltransferases as we show that distal fucosylation and the presence of an α1,6-mannose are apparently mutually exclusive. These data are thereby of importance for engineering cell lines capable of mimicking Haemonchus-type N-glycans in the preparation of recombinant proteins as vaccine candidates.

Keywords: mass spectrometry; nematode; oligosaccharide.