Crystal Structure of the Marasmius Oreades Mushroom Lectin in Complex with a Xenotransplantation Epitope

• Published in: Journal of molecular biology 2007-06, Vol.369 (3), p.710-721
• Main Authors: Grahn, Elin, Askarieh, Glareh, Holmner, Åsa, Tateno, Hiroaki, Winter, Harry C., Goldstein, Irwin J., Krengel, Ute
• Format: Article
• Language: English
• Subjects: Agaricales - metabolism; Amino Acid Sequence; carbohydrate recognition; Carbohydrates - chemistry; Crystallography, X-Ray; Dimerization; Epitopes - chemistry; fungal lectin; Lectins - chemistry; Models, Molecular; Molecular Conformation; Molecular Sequence Data; mushroom agglutinin; Protein Conformation; Protein Structure, Tertiary; Proteins - chemistry; protein–carbohydrate interactions; Ricin - chemistry; Transplantation, Heterologous; X-ray crystal structure
• ISSN: 0022-2836; 1089-8638
• DOI: 10.1016/j.jmb.2007.03.016

MOA, a lectin from the mushroom Marasmius oreades, is one of the few reagents that specifically agglutinate blood group B erythrocytes. Further, it is the only lectin known to have exclusive specificity for Galα(1,3)Gal-containing sugar epitopes, which are antigens that pose a severe barrier to animal-to-human organ transplantation. We describe here the structure of MOA at 2.4 Å resolution, in complex with the linear trisaccharide Galα(1,3)Galβ(1,4)GlcNAc. The structure is dimeric, with two distinct domains per protomer: the N-terminal lectin module adopts a ricinB/β-trefoil fold and contains three putative carbohydrate-binding sites, while the C-terminal domain serves as a dimerization interface. This latter domain, which has an unknown function, reveals a novel fold with intriguing conservation of an active site cleft. A number of indications suggest that MOA may have an enzymatic function in addition to the sugar-binding properties.