The free-living nematode Caenorhabditis elegans is a relevant model for studies on the role of glycoconjugates during development of multicellular organisms. Several genes coding for glycosyltransferases involved in the synthesis of N- and O-linked glycans have already been isolated, but, apart from repetitive dimers of glycosaminoglycans, no detailed structure of either type of component has been published so far. This study aimed to establish the structures of the major O-glycans synthesized by C. elegans to give an insight into the endogenous glycosyltransferase activities expressed in this organism. By the use of NMR and MS, we have resolved the sequence of seven of these components that present very unusual features. Most of them were characterized by the type-1 core substituted on Gal and/or GalNAc by (β1–4)Glc and (β1–6)Glc residues. Another compound exhibited the GalNAc(β1–4)N-acetylglucosaminitol sequence in the terminal position, to which was attached a tetramer of β-Gal substituted by both Fuc and 2-O-methyl-fucose residues. Our experimental procedure led also to the isolation of glycosaminoglycan-like components and oligomannosyl-type N-glycans. In particular, the data confirmed that C. elegans synthesizes the ubiquitous linker sequence GlcA(β1–3)Gal(β1–3)Gal(β1–4)Xyl.
Abbreviations used: 2-O-Me-Fuc, 2-O-methyl-fucose; GalNAc-ol, N-acetylgalactosaminitol; GlcNAc-ol, N-acetylglucosaminitol; Xyl-ol, xylitol; ΔHexA, 4-deoxy-α-l-threohex-4-enepyranosyluronic acid; ESI-MS, electrospray ionization MS; TES, Toxocara excretory-secretory; GAG, glycosaminoglycan; MALDI-TOF, matrix-assisted laser-desorption ionization–time-of-flight; ROESY, rotating-frame Overhauser enhancement spectroscopy; NOE, nuclear Overhauser effect; HMQC, heteronuclear multiple quantum coherance; β-Glcp, β-glucopyranose; β-Galp, β-galactopyranose; Hex, hexose; HexA, hexuronic acid; HexNAc-ol, N-acetylhexosaminitol.