Discovery and Structural Characterization of Fucosylated Oligomannosidic N-Glycans in Mushrooms

Department of Chemistry, University of Natural Resources and Life Sciences, 1190 Vienna, Austria.
Journal of Biological Chemistry (Impact Factor: 4.57). 02/2011; 286(8):5977-84. DOI: 10.1074/jbc.M110.191304
Source: PubMed


l-Fucose is a common constituent of Asn-linked glycans in vertebrates, invertebrates, and plants, but in fungal glycoproteins,
fucose has not been found so far. However, by mass spectrometry we detected N-glycans and O-glycans containing one to six deoxyhexose residues in fruit bodies of several basidiomycetes. The N-glycans of chanterelles (Cantharellus cibarius) contained a deoxyhexose chromatographically identical to fucose and sensitive to α-l-fucosidase. Analysis of individual glycan species by tandem MS, glycosidase digestion, and finally 1H NMR revealed the presence of l-fucose in α1,6-linkage to an α1,6-mannose of oligomannosidic N-glycans. The substitution by α1,6-mannose of α1,2-mannosyl residues of the canonical precursor structure was yet another
hitherto unknown modification. No indication for the occurrence of yet other modifications, e.g. bisecting N-acetylglucosamine, was seen. Besides fucosylated N-glycans, short O-linked mannan chains substituted with fucose were present on chanterelle proteins. Although undiscovered so far, l-fucose appears to represent a prominent feature of protein-linked glycans in the fungal kingdom.

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    • "Thus, GnT I is a key enzyme since it is the first glycosyltransferase occurring in the Golgi apparatus in the GnT I-dependent pathway giving rise to complex N-glycans that are required for normal morphogenesis in pluricellular organisms (Ioffe and Stanley, 1994; Metzler et al., 1994). A sequence encoding for a GnT I is predicted in P. tricornutum (Baïet et al., 2011) but not in C. reinhardtii (Mathieu-Rivet et al., 2013) suggesting that N-linked glycans from these two microalgae could be processed in the Golgi apparatus according to two different pathways, referred to as GnT I-dependent and GnT I-independent pathways (Zhu et al., 2004; Crispin et al., 2006; Grass et al., 2011). "
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