title: Bisecting Galactose as a Feature of N-Glycans of Wild-type and Mutant Caenorhabditis elegans.
abstract: The N-glycosylation of the model nematode Caenorhabditis elegans has proven to be highly variable and rather complex; it is an example to contradict the existing impression that "simple" organisms possess also a rather simple glycomic capacity. In previous studies in a number of laboratories, N-glycans with up to four fucose residues have been detected. However, although the linkage of three fucose residues to the N,N'-diacetylchitobiosyl core has been proven by structural and enzymatic analyses, the nature of the fourth fucose has remained uncertain. By constructing a triple mutant with deletions in the three genes responsible for core fucosylation (fut-1, fut-6 and fut-8), we have produced a nematode strain lacking products of these enzymes, but still retaining maximally one fucose residue on its N-glycans. Using mass spectrometry and HPLC in conjunction with chemical and enzymatic treatments as well as NMR, we examined a set of α-mannosidase-resistant N-glycans. Within this glycomic subpool, we can reveal that the core β-mannose can be trisubstituted and so carries not only the ubiquitous α1,3- and α1,6-mannose residues, but also a "bisecting" β-galactose, which is substoichiometrically modified with fucose or methylfucose. In addition, the α1,3-mannose can also be α-galactosylated. Our data, showing the presence of novel N-glycan modifications, will enable more targeted studies to understand the biological functions and interactions of nematode glycans.
authors.affiliation: From the ‡Department für Chemie, Universität für Bodenkultur, 1190 Wien, Austria;
authors.forename: Shi
authors.initials: S
authors.lastname: Yan
authors.affiliation: §Institut für Organische Chemie, Universität Wien, 1090 Wien, Austria;
authors.forename: Lothar
authors.initials: L
authors.lastname: Brecker
authors.affiliation: ¶Institutionen för Biomedicin, Göteborgs universitet, 405 30 Göteborg, Sweden;
authors.forename: Chunsheng
authors.initials: C
authors.lastname: Jin
authors.affiliation: From the ‡Department für Chemie, Universität für Bodenkultur, 1190 Wien, Austria;
authors.forename: Alexander
authors.initials: A
authors.lastname: Titz
authors.affiliation: From the ‡Department für Chemie, Universität für Bodenkultur, 1190 Wien, Austria;
authors.forename: Martin
authors.initials: M
authors.lastname: Dragosits
authors.affiliation: ¶Institutionen för Biomedicin, Göteborgs universitet, 405 30 Göteborg, Sweden;
authors.forename: Niclas G
authors.identifier: http://orcid.org/0000-0002-3045-2628
authors.initials: NG
authors.lastname: Karlsson
authors.affiliation: ‖Department für Chromosomenbiologie, Max F. Perutz Laboratories, Universität Wien, 1030 Wien, Austria.
authors.forename: Verena
authors.identifier: http://orcid.org/0000-0002-1978-682X
authors.initials: V
authors.lastname: Jantsch
authors.affiliation: From the ‡Department für Chemie, Universität für Bodenkultur, 1190 Wien, Austria; iain.wilson@boku.ac.at.
authors.forename: Iain B H
authors.identifier: http://orcid.org/0000-0001-8996-1518
authors.initials: IB
authors.lastname: Wilson
authors.affiliation: From the ‡Department für Chemie, Universität für Bodenkultur, 1190 Wien, Austria;
authors.forename: Katharina
authors.identifier: http://orcid.org/0000-0002-3594-7136
authors.initials: K
authors.lastname: Paschinger
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D056148:Chromatography, Reverse-Phase; D005643:Fucose / Q000378:metabolism; D005647:Fucosyltransferases / Q000378:metabolism; D005690:Galactose / Q000378:metabolism*; D055786:Gene Knockout Techniques; D006023:Glycoproteins / Q000378:metabolism; D007536:Isomerism; D008361:Mannosidases / Q000378:metabolism; D008745:Methylation; D009154:Mutation / Q000235:genetics*; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism; D020543:Proteome / Q000378:metabolism; D066244:Proton Magnetic Resonance Spectroscopy; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D006023:Glycoproteins; D011134:Polysaccharides; D020033:Protein Isoforms; D020543:Proteome; D005643:Fucose; D005647:Fucosyltransferases; D008361:Mannosidases; D005690:Galactose