The crystal structure of a plant lectin in complex with the Tn antigen.
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.
Babino
Alvaro
A
Departamento de Bioquimica, Facultad de Medicina, Av. Gral Flores 2125, Montevideo, Uruguay.
Tello
Diana
D
Rojas
Adriana
A
Bay
Sylvie
S
Osinaga
Eduardo
E
Alzari
Pedro M
PM
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
D015295:Antigens, Tumor-Associated, Carbohydrate; D046911:Macromolecular Substances; D037121:Plant Lectins; C040286:Tn antigen; C042242:Vicia lectins