Structure of O-glycosidically linked oligosaccharides from glycoproteins of Trypanosoma cruzi CL-Brener strain: evidence for the presence of O-linked sialyl-oligosaccharides.

Glycoproteins on the cell surface of Trypanosoma cruzi are known to play important roles in the interaction of the parasite with the host cells. We previously determined the structures of the O-glycan chains from the sialoglycoproteins (mucin-like molecules) of the G- and Y-strains and observed significant differences between them. We now report the structures of the sialylated and nonsialylated O-linked oligosaccharides isolated from the cell surface glycoproteins of the myotropic CL-Brener strain grown in the presence of fetal calf serum. The structures of the O-linked oligosaccharide alditols obtained by reductive beta-elimination of the sialoglycoprotein were determined by a combination of methylation analysis, fast atom bombardment-mass spectrometry and nuclear magnetic resonance spectroscopy. The presence of a beta-galactopyranose substituent on the N-acetylglucosamine O-4 position shows that these O-linked oligosaccharides from CL-Brener strain belong to the same family as those isolated from mucins expressed by T. cruzi Y strain, a reticulotropic strain. In addition, novel O-glycans, including alpha2-3 mono-sialylated species are described.