Molecular recognition of complex-type biantennary N-glycans by protein receptors: a three-dimensional view on epitope selection by NMR.
The current surge in defining glycobiomarkers by applying lectins rekindles interest in definition of the sugar-binding sites of lectins at high resolution. Natural complex-type N-glycans can present more than one potential binding motif, posing the question of the actual mode of interaction when interpreting, for example, lectin array data. By strategically combining N-glycan preparation with saturation-transfer difference NMR and modeling, we illustrate that epitope recognition depends on the structural context of both the sugar and the lectin (here, wheat germ agglutinin and a single hevein domain) and cannot always be predicted from simplified model systems studied in the solid state. We also monitor branch-end substitutions by this strategy and describe a three-dimensional structure that accounts for the accommodation of the α2,6-sialylated terminus of a biantennary N-glycan by viscumin. In addition, we provide a structural explanation for the role of terminal α2,6-sialylation in precluding the interaction of natural N-glycans with lectin from  Maackia amurensis . The approach described is thus capable of pinpointing lectin-binding motifs in natural N-glycans and providing detailed structural explanations for lectin selectivity.
Chemical and Physical Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain.
Ana
A
Ardá
Pilar
P
Blasco
Daniel
D
Varón Silva
Volker
V
Schubert
Sabine
S
André
Marta
M
Bruix
F Javier
FJ
Cañada
Hans-Joachim
HJ
Gabius
Carlo
C
Unverzagt
Jesús
J
Jiménez-Barbero
D023181:Antimicrobial Cationic Peptides / Q000737:chemistry; D001665:Binding Sites; D000939:Epitopes / Q000737:chemistry* / Q000378:metabolism; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D037121:Plant Lectins / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry* / Q000378:metabolism
D023181:Antimicrobial Cationic Peptides; D000939:Epitopes; D008024:Ligands; D037121:Plant Lectins; D011134:Polysaccharides; C045875:hevein