The crystal structure of the Calystegia sepium agglutinin reveals a novel quaternary arrangement of lectin subunits with a beta-prism fold.
The high number of quaternary structures observed for lectins highlights the important role of these oligomeric assemblies during carbohydrate recognition events. Although a large diversity in the mode of association of lectin subunits is frequently observed, the oligomeric assemblies of plant lectins display small variations within a single family. The crystal structure of the mannose-binding jacalin-related lectin from Calystegia sepium (Calsepa) has been determined at 1.37-A resolution. Calsepa exhibits the same beta-prism fold as identified previously for other members of the family, but the shape and the hydrophobic character of its carbohydrate-binding site is unlike that of other members, consistent with surface plasmon resonance analysis showing a preference for methylated sugars. Calsepa reveals a novel dimeric assembly markedly dissimilar to those described earlier for Heltuba and jacalin but mimics the canonical 12-stranded beta-sandwich dimer found in legume lectins. The present structure exemplifies the adaptability of the beta-prism building block in the evolution of plant lectins and highlights the biological role of these quaternary structures for carbohydrate recognition.
Bourne
Yves
Y
AFMB-CNRS, CNRS UMR6098, F13402 Marseille Cedex 20, France. yves@afmb.cnrs-mrs.fr
Roig-Zamboni
Véronique
V
Barre
Annick
A
Peumans
Willy J
WJ
Astoul
Corinne Houlès
CH
Van Damme
Els J M
EJ
Rougé
Pierre
P
D000595:Amino Acid Sequence; D031253:Calystegia / Q000737:chemistry*; D018360:Crystallography, X-Ray; D007700:Kinetics; D037102:Lectins / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009005:Monosaccharides / Q000737:chemistry; D037121:Plant Lectins / Q000737:chemistry* / Q000302:isolation & purification; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D021122:Protein Subunits / Q000737:chemistry; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D037102:Lectins; D009005:Monosaccharides; D037121:Plant Lectins; D021122:Protein Subunits