title: Major O-glycans in the spores of two microsporidian parasites are represented by unbranched manno-oligosaccharides containing alpha-1,2 linkages.
abstract: 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 alpha1, 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.
authors.affiliation: Equipe Parasitologie Moléculaire et Cellulaire, LBP, CNRS UMR6023, Université Blaise Pascal, 24 Avenue des Landais, 63177 Aubière Cedex, France.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Taupin
authors.forename: Estelle
authors.initials: E
authors.lastname: Garenaux
authors.forename: Muriel
authors.initials: M
authors.lastname: Mazet
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Maes
authors.forename: Hubert
authors.initials: H
authors.lastname: Denise
authors.forename: Gérard
authors.initials: G
authors.lastname: Prensier
authors.forename: Christian P
authors.initials: CP
authors.lastname: Vivarès
authors.forename: Yann
authors.initials: Y
authors.lastname: Guérardel
authors.forename: Guy
authors.initials: G
authors.lastname: Méténier
mesh_terms: D015180:Electrophoresis, Gel, Two-Dimensional; D009670:Encephalitozoon cuniculi / Q000737:chemistry; D006023:Glycoproteins / Q000032:analysis; D008358:Mannose / Q000737:chemistry / Q000378:metabolism; D037241:Mannose-Binding Lectins / Q000378:metabolism; D013058:Mass Spectrometry; D016814:Microsporidia / Q000737:chemistry*; D009844:Oligosaccharides / Q000032:analysis* / Q000378:metabolism; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase / Q000378:metabolism; D010796:Phthalic Anhydrides / Q000494:pharmacology; D011108:Polymers / Q000494:pharmacology; D011134:Polysaccharides / Q000032:analysis*; D013172:Spores, Fungal / Q000737:chemistry* / Q000187:drug effects
chemical_list: D006023:Glycoproteins; D037241:Mannose-Binding Lectins; D009844:Oligosaccharides; D010796:Phthalic Anhydrides; D011108:Polymers; D011134:Polysaccharides; C465963:poly(phthalic anhydride-co-trimellitic anhydride-co-glycols); D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D008358:Mannose