title: Structure and specificity of a binary tandem domain F-lectin from striped bass (Morone saxatilis).
abstract: The plasma of the striped bass Morone saxatilis contains a fucose-specific lectin (MsaFBP32) that consists of two F-type carbohydrate recognition domains (CRDs) in tandem. The crystal structure of the complex of MsaFBP32 with l-fucose reported here shows a cylindrical 81-A-long and 60-A-wide trimer divided into two globular halves: one containing N-terminal CRDs (N-CRDs) and the other containing C-terminal CRDs (C-CRDs). The resulting binding surfaces at the opposite ends of the cylindrical trimer have the potential to cross-link cell surface or humoral carbohydrate ligands. The N-CRDs and C-CRDs of MsaFBP32 exhibit significant structural differences, suggesting that they recognize different glycans. Analysis of the carbohydrate binding sites provides the structural basis for the observed specificity of MsaFBP32 for simple carbohydrates and suggests that the N-CRD recognizes more complex fucosylated oligosaccharides and with a relatively higher avidity than the C-CRD. Modeling of MsaFBP32 complexed with fucosylated glycans that are widely distributed in prokaryotes and eukaryotes rationalizes the observation that binary tandem CRD F-type lectins function as opsonins by cross-linking "non-self" carbohydrate ligands and "self" carbohydrate ligands, such as sugar structures displayed by microbial pathogens and glycans on the surface of phagocytic cells from the host.
authors.affiliation: Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA. bianchet@jhmi.edu
authors.forename: Mario A
authors.initials: MA
authors.lastname: Bianchet
authors.forename: Eric W
authors.initials: EW
authors.lastname: Odom
authors.forename: Gerardo R
authors.initials: GR
authors.lastname: Vasta
authors.forename: L Mario
authors.initials: LM
authors.lastname: Amzel
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001492:Bass / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D018360:Crystallography, X-Ray; D029941:Fish Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005643:Fucose / Q000378:metabolism; D037102:Lectins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity
chemical_list: D029941:Fish Proteins; D037102:Lectins; C027112:fucose-binding lectin; D005643:Fucose