Structure of a lectin from Canavalia gladiata seeds: new structural insights for old molecules

Abstract

BackgroundLectins are mainly described as simple carbohydrate-binding proteins. Previous studies have tried to identify other binding sites, which possible recognize plant hormones, secondary metabolites, and isolated amino acid residues. We report the crystal structure of a lectin isolated from Canavalia gladiata seeds (CGL), describing a new binding pocket, which may be related to pathogen resistance activity in ConA-like lectins; a site where a non-protein amino-acid, α-aminobutyric acid (Abu), is bound.ResultsThe overall structure of native CGL and complexed with α-methyl-mannoside and Abu have been refined at 2.3 Å and 2.31 Å resolution, respectively. Analysis of the electron density maps of the CGL structure shows clearly the presence of Abu, which was confirmed by mass spectrometry.ConclusionThe presence of Abu in a plant lectin structure strongly indicates the ability of lectins on carrying secondary metabolites. Comparison of the amino acids composing the site with other legume lectins revealed that this site is conserved, providing an evidence of the biological relevance of this site. This new action of lectins strengthens their role in defense mechanisms in plants.

Crystallization and preliminary X-ray diffraction analysis of the lectin fromCanavalia bolivianaPiper seeds

“…1b) are non-religated products of this process and the chain is the mature protein. The Diocleinae lectins used for comparison, ConBr and CGL, have previously been characterized and their three-dimensional structures have been determined (PDB code 1azd, Sanz-Aparicio et al, 1997; PDB code 2d7f, Delatorre et al, 2007).…”

“…The preliminary crystal structure of Cbol was determined by standard molecular-replacement methods using the program MOLREP (Vagin & Teplyakov, 1997). Various monomers were tested for molecular replacement and the best result was obtained using CGL (PDB code 2d7f; Delatorre et al, 2007) as a structural model. The best solution had a final correlation coefficient of 0.705 and an R factor of 0.424.…”

Purification, Characterization, and Preliminary X-Ray Diffraction Analysis of a Lactose-Specific Lectin from Cymbosema roseum Seeds

“…2; Gallego del Sol, F., Chornet, J. J. C., & Cavada, B. S. PDBcode: 2GDF; to be published) [4,15,[32][33][34][35][36][37][38][39][40][41][42]. A sequence alignment of the sequenced peptides of CRLII against other legume lectin sequence displays a similarity of 53% and 44% with the galactose-specific lectins VML and Rob, respectively (Fig.…”

“…2 Phylogenetic analysis based on legume lectins sequence alignment. The protein sequence alignment made among partial CRLII sequence with legume seed lectins: CRLI [15], Dgran [35], Dioclea guianensis lectin (Dgui) [37], Dioclea violacea lectin (DVL; Gallego del Sol, F., Chornet, J. J. C., & Cavada, B. S. PDBcode: 2GDF; to be published), Dioclea lehmanii lectin (DLLI) [4], Canavalia gladiata lectin (CGL) [38], ConA [30], ConBr [34], Acacia farnesiana lectin-like protein (AFAL) [39], PHAL [40], PHA [36], Dolichos biflorus lectin (DBL) [41], VML [32], Rob [33], and Dolichos lablab lectin (Dlab) [42]. The alignment and phylogram was generated using CLUSTALW web program Protein Crystallization and X-ray Data Collection…”

A Lectin from Platypodium elegans with Unusual Specificity and Affinity for Asymmetric Complex N-Glycans

“…The direct interference with viruses and microorganisms is rather exceptional, but the deleterious effects of plant lectins on both predatory invertebrates and animals are well documented (5). The existence of hydrophobic sites within the structure of leguminous lectins, which bind phytohormones, suggests a possible role in certain aspects of hormonally regulated plant growth and development (7).…”