title: Structure of S-lectin, a developmentally regulated vertebrate beta-galactoside-binding protein.
abstract: The crystal structure of a 14-kDa bovine spleen S-lectin complexed with the disaccharide N-acetyllactosamine at 1.9-A resolution reveals a surprising structural relationship to legume lectins, despite the lack of sequence homology. Two monomers associate to form an extended beta-sandwich, each with the same jelly roll topology typical of legume lectins but with dramatically trimmed loops and with different dimer association. Each monomer binds one N-acetyllactosamine molecule in a topologically and spatially different site than that of legume lectins. The carbohydrate-binding site provides an unprecedented paradigm for carbohydrate binding, with a unique network of salt bridges. The specificity for beta-galactose arises from intricate interactions that constrain the position of the O4 atom.
authors.affiliation: Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville 20850.
authors.forename: D I
authors.initials: DI
authors.lastname: Liao
authors.forename: G
authors.initials: G
authors.lastname: Kapadia
authors.forename: H
authors.initials: H
authors.lastname: Ahmed
authors.forename: G R
authors.initials: GR
authors.lastname: Vasta
authors.forename: O
authors.initials: O
authors.lastname: Herzberg
mesh_terms: D000606:Amino Sugars / Q000737:chemistry*; D000818:Animals; D002240:Carbohydrate Sequence; D002417:Cattle; D018360:Crystallography, X-Ray; D005697:Galactosides / Q000737:chemistry*; D037102:Lectins / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D037121:Plant Lectins; D011487:Protein Conformation; D013154:Spleen / Q000737:chemistry
chemical_list: D000606:Amino Sugars; D005697:Galactosides; D037102:Lectins; D037121:Plant Lectins; C036292:pea lectin; C000458:N-acetyllactosamine