title: The first crystal structure of a Mimosoideae lectin reveals a novel quaternary arrangement of a widespread domain.
abstract: The crystal structures of the apo and mannose-bound Parkia platycephala seed lectin represent the first structure of a Mimosoideae lectin and a novel circular arrangement of beta-prism domains, and highlight the adaptability of the beta-prism fold as a building block in the evolution of plant lectins. The P.platycephala lectin is a dimer both in solution and in the crystals. Mannose binding to each of the three homologous carbohydrate-recognition domains of the lectin occurs through different modes, and restrains the flexibility of surface-exposed loops and residues involved in carbohydrate recognition. The planar array of carbohydrate-binding sites on the rim of the toroid-shaped structure of the P.platycephala lectin dimer immediately suggests a mechanism to promote multivalent interactions leading to cross-linking of carbohydrate ligands as part of the host strategy against phytopredators and pathogens. The cyclic structure of the P.platycephala lectin points to the convergent evolution of a structural principle for the construction of lectins involved in host defense or in attacking other organisms.
authors.affiliation: Instituto de Biomedicina de Valencia, CSIC, E-46010 Valencia, Spain.
authors.forename: Francisca
authors.initials: F
authors.lastname: Gallego del Sol
authors.forename: Celso
authors.initials: C
authors.lastname: Nagano
authors.forename: Benildo S
authors.initials: BS
authors.lastname: Cavada
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Calvete
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D037102:Lectins / Q000737:chemistry* / Q000378:metabolism; D008358:Mannose / Q000378:metabolism; D031298:Mimosa / Q000737:chemistry*; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D017386:Sequence Homology, Amino Acid
chemical_list: D037102:Lectins; D008358:Mannose