Structural basis of carbohydrate recognition by a Man(alpha1-2)Man-specific lectin from Bowringia milbraedii.
The crystal structure of the seed lectin from the tropical legume Bowringia milbraedii was determined in complex with the disaccharide ligand Man(alpha1-2)Man. In solution, the protein exhibits a dynamic dimer-tetramer equilibrium, consistent with the concanavalin A-type tetramer observed in the crystal. Contacts between the tetramers are mediated almost exclusively through the carbohydrate ligand, resulting in a crystal lattice virtually identical to that of the concanavalin-A:Man(alpha1-2)Man complex, even though both proteins have less than 50% sequence identity. The disaccharide binds exclusively in a "downstream" binding mode, with the non-reducing mannose occupying the monosaccharide-binding site. The reducing mannose is bound in a predominantly polar subsite involving Tyr131, Gln218, and Tyr219.
Laboratorium voor Ultrastructuur, Vrije Universiteit Brussel and Department of Molecular and Cellular Interactions, Vlaams Interuniversitair Instituut voor Biotechnologie, Pleinlaan 2, B-1050 Brussels, Belgium. lievbuts@vub.ac.be
Lieven
L
Buts
Abel
A
Garcia-Pino
Lode
L
Wyns
Remy
R
Loris
D001665:Binding Sites; D002241:Carbohydrates / Q000737:chemistry; D018360:Crystallography, X-Ray; D019281:Dimerization; D004187:Disaccharides / Q000737:chemistry*; D007887:Fabaceae / Q000378:metabolism*; D037241:Mannose-Binding Lectins / Q000737:chemistry*; D008362:Mannosides / Q000737:chemistry*; D037121:Plant Lectins / Q000737:chemistry*; D020836:Protein Structure, Quaternary; D012639:Seeds / Q000378:metabolism; D012996:Solutions / Q000737:chemistry
D002241:Carbohydrates; D004187:Disaccharides; D037241:Mannose-Binding Lectins; D008362:Mannosides; D037121:Plant Lectins; D012996:Solutions; C475460:mannosyl alpha(1-6)-mannoside