title: Crystal structure of the GalNAc/Gal-specific agglutinin from the phytopathogenic ascomycete Sclerotinia sclerotiorum reveals novel adaptation of a beta-trefoil domain.
abstract: A lectin from the phytopathogenic ascomycete Sclerotinia sclerotiorum that shares only weak sequence similarity with characterized fungal lectins has recently been identified. S. sclerotiorum agglutinin (SSA) is a homodimeric protein consisting of two identical subunits of approximately 17 kDa and displays specificity primarily towards Gal/GalNAc. Glycan array screening indicates that SSA readily interacts with Gal/GalNAc-bearing glycan chains. The crystal structures of SSA in the ligand-free form and in complex with the Gal-beta1,3-GalNAc (T-antigen) disaccharide have been determined at 1.6 and 1.97 A resolution, respectively. SSA adopts a beta-trefoil domain as previously identified for other carbohydrate-binding proteins of the ricin B-like lectin superfamily and accommodates terminal non-reducing galactosyl and N-acetylgalactosaminyl glycans. Unlike other structurally related lectins, SSA contains a single carbohydrate-binding site at site alpha. SSA reveals a novel dimeric assembly markedly dissimilar to those described earlier for ricin-type lectins. The present structure exemplifies the adaptability of the beta-trefoil domain in the evolution of fungal lectins.
authors.affiliation: Architecture et Fonction des Macromolécules Biologiques UMR-6098 CNRS, Université Aix-Marseille, Campus Luminy, Case 932, F-13288 Marseille cedex 09, France.
authors.forename: Gerlind
authors.initials: G
authors.lastname: Sulzenbacher
authors.forename: Véronique
authors.initials: V
authors.lastname: Roig-Zamboni
authors.forename: Willy J
authors.initials: WJ
authors.lastname: Peumans
authors.forename: Pierre
authors.initials: P
authors.lastname: Rougé
authors.forename: Els J M
authors.initials: EJ
authors.lastname: Van Damme
authors.forename: Yves
authors.initials: Y
authors.lastname: Bourne
mesh_terms: D000373:Agglutinins / Q000737:chemistry*; D000595:Amino Acid Sequence; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000378:metabolism; D001203:Ascomycota / Q000737:chemistry*; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D005656:Fungal Proteins / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
chemical_list: D000373:Agglutinins; D015295:Antigens, Tumor-Associated, Carbohydrate; D005656:Fungal Proteins; C016467:Thomsen-Friedenreich antigen