title: Structural bases for N-glycan processing by mannoside phosphorylase.
abstract: The first crystal structure of Uhgb_MP, a β-1,4-mannopyranosyl-chitobiose phosphorylase belonging to the GH130 family which is involved in N-glycan degradation by human gut bacteria, was solved at 1.85 Å resolution in the apo form and in complex with mannose and N-acetylglucosamine. SAXS and crystal structure analysis revealed a hexameric structure, a specific feature of GH130 enzymes among other glycoside phosphorylases. Mapping of the -1 and +1 subsites in the presence of phosphate confirmed the conserved Asp104 as the general acid/base catalytic residue, which is in agreement with a single-step reaction mechanism involving Man O3 assistance for proton transfer. Analysis of this structure, the first to be solved for a member of the GH130_2 subfamily, revealed Met67, Phe203 and the Gly121-Pro125 loop as the main determinants of the specificity of Uhgb_MP and its homologues towards the N-glycan core oligosaccharides and mannan, and the molecular bases of the key role played by GH130 enzymes in the catabolism of dietary fibre and host glycans.
authors.affiliation: Université de Toulouse; INSA, UPS, INP; LISBP, 135 Avenue de Rangueil, 31077 Toulouse, France.
authors.forename: Simon
authors.initials: S
authors.lastname: Ladevèze
authors.affiliation: Université de Toulouse; INSA, UPS, INP; LISBP, 135 Avenue de Rangueil, 31077 Toulouse, France.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Cioci
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, BP 48, Saint Aubin, 91192 Gif-sur-Yvette CEDEX, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Roblin
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale (IPBS), Centre National de la Recherche Scientifique (CNRS), 205 Route de Narbonne, BP 64182, 31077 Toulouse, France.
authors.forename: Lionel
authors.initials: L
authors.lastname: Mourey
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale (IPBS), Centre National de la Recherche Scientifique (CNRS), 205 Route de Narbonne, BP 64182, 31077 Toulouse, France.
authors.forename: Samuel
authors.initials: S
authors.lastname: Tranier
authors.affiliation: Université de Toulouse; INSA, UPS, INP; LISBP, 135 Avenue de Rangueil, 31077 Toulouse, France.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Potocki-Véronèse
mesh_terms: D000595:Amino Acid Sequence; D008958:Models, Molecular; D008969:Molecular Sequence Data; D006005:Phosphorylases / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry*; D011487:Protein Conformation; D053838:Scattering, Small Angle; D017386:Sequence Homology, Amino Acid; D014961:X-Ray Diffraction
chemical_list: D011134:Polysaccharides; D006005:Phosphorylases
keywords: GH130 enzymes; N-glycans; glycoside phosphorylases; human gut microbiota