title: The crystal structure of a plant lectin in complex with the Tn antigen.
abstract: The structure of the tetrameric Vicia villosa isolectin B4 (VVLB4) in complex with a cancer antigen, the Tn glycopeptide (GalNAc-O-Ser), was determined at 2.7 A resolution. The N-acetylgalactoside moiety of the ligand binds to the primary combining site of VVLB4 in a similar way as observed for other Gal/GalNAc-specific plant lectins. The amino acid moiety of the Tn antigen is largely exposed to the solvent and makes few contacts with the protein. The structure of the complex provides a framework to understand the differences in the strength of VVLB4 binding to different sugars and emphasizes the role of a single protein residue, Tyr127, as a structural determinant of Tn-binding specificity.
authors.affiliation: Departamento de Bioquimica, Facultad de Medicina, Av. Gral Flores 2125, Montevideo, Uruguay.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Babino
authors.forename: Diana
authors.initials: D
authors.lastname: Tello
authors.forename: Adriana
authors.initials: A
authors.lastname: Rojas
authors.forename: Sylvie
authors.initials: S
authors.lastname: Bay
authors.forename: Eduardo
authors.initials: E
authors.lastname: Osinaga
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Alzari
mesh_terms: D015295:Antigens, Tumor-Associated, Carbohydrate / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D018360:Crystallography, X-Ray; D046911:Macromolecular Substances; D008958:Models, Molecular; D037121:Plant Lectins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D015295:Antigens, Tumor-Associated, Carbohydrate; D046911:Macromolecular Substances; D037121:Plant Lectins; C040286:Tn antigen; C042242:Vicia lectins