Ablation of N-acetylglucosaminyltransferases in Caenorhabditis induces expression of unusual intersected and bisected N-glycans

• Published in: Biochimica et biophysica acta. General subjects Vol. 1862; no. 10; pp. 2191 - 2203
• Main Authors: Yan, Shi, Wang, Huijie, Schachter, Harry, Jin, Chunsheng, Wilson, Iain B.H., Paschinger, Katharina
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.10.2018
• Subjects: Animals; Animals, Genetically Modified - genetics; Animals, Genetically Modified - metabolism; Caenorhabditis elegans; Caenorhabditis elegans - enzymology; Caenorhabditis elegans - genetics; Caenorhabditis elegans Proteins - chemistry; Caenorhabditis elegans Proteins - genetics; enzymatic hydrolysis; eukaryotic cells; genes; Glycomics; GlycomicsN-glycansNematode; Glycosylation; Golgi apparatus; mannose; Molecular Biology; Molekylärbiologi; mutants; Mutation; N-Acetylglucosaminyltransferases - antagonists & inhibitors; N-Acetylglucosaminyltransferases - genetics; N-glycans; Nematode; plasticity; Polysaccharides - chemistry; Polysaccharides - metabolism; transferases; Nematode; Glycomics; N-glycans
• ISSN: 0304-4165; 1872-8006
• DOI: 10.1016/j.bbagen.2018.07.002

The modification in the Golgi of N-glycans by N-acetylglucosaminyltransferase I (GlcNAc-TI, MGAT1) can be considered to be a hallmark of multicellular eukaryotes as it is found in all metazoans and plants, but rarely in unicellular organisms. The enzyme is key for the normal processing of N-glycans to either complex or paucimannosidic forms, both of which are found in the model nematode Caenorhabditis elegans. Unusually, this organism has three different GlcNAc-TI genes (gly-12, gly-13 and gly-14); therefore, a complete abolition of GlcNAc-TI activity required the generation of a triple knock-out strain. Previously, the compositions of N-glycans from this mutant were described, but no detailed structures. Using an off-line HPLC-MALDI-TOF-MS approach combined with exoglycosidase digestions and MS/MS, we reveal that the multiple hexose residues of the N-glycans of the gly-12;gly-13;gly-14 triple mutant are not just mannose, but include galactoses in three different positions (β-intersecting, β-bisecting and α-terminal) on isomeric forms of Hex4-8HexNAc2 structures; some of these structures are fucosylated and/or methylated. Thus, the N-glycomic repertoire of Caenorhabditis is even wider than expected and exhibits a large degree of plasticity even in the absence of key glycan processing enzymes from the Golgi apparatus. [Display omitted] •Deletion of GlcNAc-TI genes in Caenorhabditis leads to a major glycomic shift.•Off-line HPLC-MALDI-TOF MS reveals new N-glycan structures.•Intersecting galactose with or without a fucose substitution is a new glycan motif.