Major O-glycans in the spores of two microsporidian parasites are represented by unbranched manno-oligosaccharides containing α-1,2 linkages

• Published in: Glycobiology (Oxford) Vol. 17; no. 1; pp. 56 - 67
• Main Authors: Taupin, Vanessa, Garenaux, Estelle, Mazet, Muriel, Maes, Emmanuel, Denise, Hubert, Prensier, Gérard, Vivarès, Christian P, Guérardel, Yann, Méténier, Guy
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 2007; Oxford University Press (OUP)
• Subjects: Biochemistry; Biochemistry, Molecular Biology; Electrophoresis, Gel, Two-Dimensional; Encephalitozoon cuniculi; Encephalitozoon cuniculi - chemistry; glycan analysis; Glycoproteins; Glycoproteins - analysis; Life Sciences; Mannose; Mannose - chemistry; Mannose - metabolism; Mannose-Binding Lectins; Mannose-Binding Lectins - metabolism; Mass Spectrometry; Microbiology and Parasitology; Microsporidia; Microsporidia - chemistry; O-mannosylation; Oligosaccharides; Oligosaccharides - analysis; Oligosaccharides - metabolism; Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase - metabolism; Phthalic Anhydrides; Phthalic Anhydrides - pharmacology; polar cap; Polymers; Polymers - pharmacology; Polysaccharides; Polysaccharides - analysis; Spores, Fungal; Spores, Fungal - chemistry; Spores, Fungal - drug effects; Structural Biology; ultracytochemistry; O-mannosylation; polar cap; ultracytochemistry; microsporidia; glycan analysis
• ISSN: 0959-6658; 1460-2423
• DOI: 10.1093/glycob/cwl050

Protein glycosylation in microsporidia, a fungi-related group comprising exclusively obligate intracellular parasitic species, is still poorly documented. Here, we have studied glycoconjugate localization and glycan structures in spores of Encephalitozoon cuniculi and Antonospora locustae, two distantly related microsporidians invading mammalian and insect hosts, respectively. The polar sac-anchoring disc complex or polar cap, an apical element of the sporal invasion apparatus, was strongly periodic acid-thiocarbohydrazide-Ag proteinate-positive. Mannose-binding lectins reacted with the polar cap and recognized several bands (from 20 to 160 kDa) on blots of E. cuniculi protein extracts. Physicochemical analyses provided the first determination of major glycostructures in microsporidia. O-linked glycans were demonstrated to be linear manno-oligosaccharides containing up to eight α1, 2-linked mannose residues, thus resembling those reported in some fungi such as Candida albicans. No N-linked glycans were detected. The data are in accordance with gene-based prediction of a minimal O-mannosylation pathway. Further identification of individual mannoproteins should help in the understanding of spore germination mechanism and host-microsporidia interactions.