earticle

영어

Cryptococcus neoformans is an encapsulated basidiomycete causing cryptococcosis in immunocompromised individuals such as AIDS patients. Previous studies show that cell surface mannoproteins of C. neoformans stimulated host T-cell responses indicating that these protein are involved in pathogenicity. However, the structure of N-linked oligosaccharides assembled oncryptococcal cell wall mannoproteins has not yet been elucidated. In order to obtain comprehensive information on the structure of N-linked glycans in various serotypes of C. neoformans, the profiles of N-linked oligosaccharides obtained from cell wall mannoproteins were analysed by MALDI-TOP and HPLC. Exoglycosidase treatment revealed that C. neoformansN-glycans were mostly composed of α1,2- and α1,6-linked mannose residues. Notably, the neutral N-glycans of serotypes A and D were shown to have high-mannose type N-glycans with a β1,2-xylose residue, which is attached to the trimannosyl-core of N-glycans, whereas those of serotype B were shown to be much shorter and devoid of a xylose residue. Further analysis of the acidic N-glycans of C. neoformans indicated the presence of xylose-phosphate residues in the core and outer regions of N-glycans regardless of serotypes, but with quite differential extent. The N-glycan profiles lacking both xylose and xylose-phosphate residues in the C. neoformansuxs1Δ mutant strongly indicated that UDP-xylose is used as a donor sugar for the addition of a xylose or a xylose-phosphate residue to the N-glycans. Our data present the first report on the unique structure of N-glycans in C. neoformans, which is quite different from those of other yeast and fungal species.