title: Crystal structure of a β-prism II lectin from Remusatia vivipara.
abstract: The crystal structure of a β-prism II (BP2) fold lectin from Remusatia vivipara, a plant of traditional medicinal value, has been determined at a resolution of 2.4 Å. This lectin (RVL, Remusatia vivipara lectin) is a dimer with each protomer having two distinct BP2 domains without a linker between them. It belongs to the "monocot mannose-binding" lectin family, which consists of proteins of high sequence and structural similarity. Though the overall tertiary structure is similar to that of lectins from snowdrop bulbs and garlic, crucial differences in the mannose-binding regions and oligomerization were observed. Unlike most of the other structurally known proteins in this family, only one of the three carbohydrate recognition sites (CRSs) per BP2 domain is found to be conserved. RVL does not recognize simple mannose moieties. RVL binds to only N-linked complex glycans like those present on the gp120 envelope glycoprotein of HIV and mannosylated blood proteins like fetuin, but not to simple mannose moieties. The molecular basis for these features and their possible functional implications to understand the different levels of carbohydrate affinities in this structural family have been investigated through structure analysis, modeling and binding studies. Apart from being the first structure of a lectin to be reported from the Araceae/Arum family, this protein also displays a novel mode of oligomerization among BP2 lectins.
authors.affiliation: Molecular Biophysics Unit,  Indian Institute of Science, Bangalore 560 012,  India.
authors.forename: Kartika N
authors.initials: KN
authors.lastname: Shetty
authors.forename: Ganapati G
authors.initials: GG
authors.lastname: Bhat
authors.forename: Shashikala R
authors.initials: SR
authors.lastname: Inamdar
authors.forename: Bale M
authors.initials: BM
authors.lastname: Swamy
authors.forename: K
authors.initials: K
authors.lastname: Suguna
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D031060:Colocasia; D018360:Crystallography, X-Ray; D015699:HIV Envelope Protein gp120 / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D037121:Plant Lectins / Q000737:chemistry* / Q000235:genetics; D011134:Polysaccharides / Q000737:chemistry; D011485:Protein Binding; D021382:Protein Sorting Signals; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein
chemical_list: D015699:HIV Envelope Protein gp120; D037121:Plant Lectins; D011134:Polysaccharides; D021382:Protein Sorting Signals; C514793:gp120 protein, Human immunodeficiency virus 1