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Taxonomic group: fungi / Basidiomycota (Phylum: Basidiomycota)
Associated disease: infection due to Cryptococcus neoformans [ICD11: XN3EH

]

NCBI PubMed ID: 27986834
Publication DOI: 10.1093/glycob/cww127
Journal NLM ID: 9104124
Publisher: IRL Press at Oxford University Press
Correspondence: luciamp

biof.ufrj.br (Lucia Mendonca-Previato)
Institutions: National Research Council, 100 Sussex Dr, K1A 0R6 Ottawa, Canada, Laboratorio de Glicobiologia, Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941902 Rio de Janeiro, Brazil, Universite Lille, CNRS, UMR 8576, UGSF, Unite de Glycobiologie Structurale et Fonctionnelle, F 59000 Lille, France

Galactoxylomannans (GalXMs) are a mixture of neutral and acidic capsular polysaccharides produced by the opportunistic fungus Cryptococcus neoformans that exhibit potent suppressive effects on the host immune system. Previous studies describing the chemical structure of C. neoformans GalXMs have reported species without O-acetyl substituents. Herein we describe that C. neoformans grown in capsule-inducing medium produces highly O-acetylated GalXMs. The location of the O-acetyl groups was determined by nuclear magnetic resonance (NMR) spectroscopy. In the neutral GalXM (NGalXM), 80% of 3-linked mannose (α-Manp) residues present in side chains are acetylated at the O-2 position. In the acidic GalXM also termed glucuronoxylomannogalactan (GXMGal), 85% of the 3-linked α-Manp residues are acetylated either in the O-2 (75%) or in the O-6 (25%) position, but O-acetyl groups are not present at both positions simultaneously. In addition, NMR spectroscopy and methylation analysis showed that β-galactofuranose (β-Galf) units are linked to O-2 and O-3 positions of nonbranched α-galactopyranose (α-Galp) units present in the GalXMs backbone chain. These findings highlight new structural features of C. neoformans GalXMs. Among these features, the high degree of O-acetylation is of particular interest, since O-acetyl group-containing polysaccharides are known to possess a range of immunobiological activities.

capsular polysaccharides, galactofuranose, O-acetyl, NMR-spectroscopy, Cryptococcus, Cryptococcus neoformans, galactoxylomannans

Structure type: polymer chemical repeating unit
Location inside paper: p.586, fig.4C
Trivial name: acidic glucuronoxylomannogalactan (GXMGal)
Compound class: CPS
Contained glycoepitopes: IEDB_114701,IEDB_115136,IEDB_130701,IEDB_134624,IEDB_136044,IEDB_136095,IEDB_136906,IEDB_137472,IEDB_140630,IEDB_141794,IEDB_144983,IEDB_145668,IEDB_151528,IEDB_152206,IEDB_164174,IEDB_167188,IEDB_174332,IEDB_190606,IEDB_423153,IEDB_983930,SB_163,SB_165,SB_166,SB_187,SB_195,SB_197,SB_44,SB_67,SB_7,SB_72,SB_88

Methods: 13C NMR, 1H NMR, methylation, gel filtration, NMR-2D, GC-MS, acid hydrolysis, GC, composition analysis, methanolysis, HPLC, ion-exchange chromatography, reduction with NaBD4, SEC, O-acetylation, dialysis
Comments, role: acidic oligosaccharide-repeating unit of GXMGal proposed by Heiss et al. (2013).

Related record ID(s): 11954, 12211, 12212, 12213, 12214, 12216, 12217, 12218, 12219, 12220, 48780, 48782
NCBI Taxonomy refs (TaxIDs): 5207
Reference(s) to other database(s): GTC:G77279OV
Show glycosyltransferases

There is only one chemically distinct structure:

*OC[C@H]1O[C@H](OC[C@H]2O[C@H](*)[C@H](O[C@@H]3O[C@@H]([C@H](O)CO)[C@H](O)[C@H]3O)[C@@H](O[C@@H]3O[C@H](CO)[C@H](O[C@H]4O[C@H](CO)[C@@H](O)[C@H](O[C@H]5O[C@H](CO)[C@@H](O)[C@H](O[C@@H]6OC[C@@H](O)[C@H](O)[C@H]6O)[C@@H]5OC(C)=O)[C@@H]4O[C@@H]4OC[C@@H](O)[C@H](O)[C@H]4O)[C@H](O[C@@H]4O[C@H](C(=O)O)[C@@H](O)[C@H](O)[C@H]4O)[C@H]3O)[C@H]2O)[C@H](O)[C@@H](O)[C@H]1O

SVG MW SMILES 3D mol Ionize