Dataset Information

Glycan dependence of Galectin-3 self-association properties.

ABSTRACT: Human Galectin-3 is found in the nucleus, the cytoplasm and at the cell surface. This lectin is constituted of two domains: an unfolded N-terminal domain and a C-terminal Carbohydrate Recognition Domain (CRD). There are still uncertainties about the relationship between the quaternary structure of Galectin-3 and its carbohydrate binding properties. Two types of self-association have been described for this lectin: a C-type self-association and a N-type self-association. Herein, we have analyzed Galectin-3 oligomerization by Dynamic Light Scattering using both the recombinant CRD and the full length lectin. Our results proved that LNnT induces N-type self-association of full length Galectin-3. Moreover, from Nuclear Magnetic Resonance (NMR) and Surface Plasmon Resonance experiments, we observed no significant specificity or affinity variations for carbohydrates related to the presence of the N-terminal domain of Galectin-3. NMR mapping clearly established that the N-terminal domain interacts with the CRD. We propose that LNnT induces a release of the N-terminal domain resulting in the glycan-dependent self-association of Galectin-3 through N-terminal domain interactions.

SUBMITTER: Halimi H

PROVIDER: S-EPMC4219786 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Glycan dependence of Galectin-3 self-association properties.

Halimi Hubert H Rigato Annafrancesca A Byrne Deborah D Ferracci Géraldine G Sebban-Kreuzer Corinne C ElAntak Latifa L Guerlesquin Francoise F

PloS one 20141104 11

Human Galectin-3 is found in the nucleus, the cytoplasm and at the cell surface. This lectin is constituted of two domains: an unfolded N-terminal domain and a C-terminal Carbohydrate Recognition Domain (CRD). There are still uncertainties about the relationship between the quaternary structure of Galectin-3 and its carbohydrate binding properties. Two types of self-association have been described for this lectin: a C-type self-association and a N-type self-association. Herein, we have analyzed ...[more]

PMID: 25369125

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Project description:gal-1 (galectin-1) mediates cell-cell and cell-extracellular matrix adhesion, essentially by interacting with beta-galactoside-containing glycans of cell-surface glycoconjugates. Although most structural studies with gal-1 have investigated its binding to simple carbohydrates, in particular lactose and N-acetyl-lactosamine, this view is limited, because gal-1 functions at the cell surface by interacting with more complex glycans that are heterogeneous in size and composition. In the present study we used NMR spectroscopy to investigate the interaction of human gal-1 with a large (120 kDa) complex glycan, GRG (galactorhamnogalacturonate glycan), that contains non-randomly distributed mostly terminal beta(1-->4)-linked galactose side chains. We used 15N-1H-HSQC (heteronuclear single quantum coherence) NMR experiments with 15N-enriched gal-1 to identify the GRG-binding region on gal-1 and found that this region covers a large surface area on gal-1 that includes the quintessential lactose-binding site and runs from that site through a broad valley or cleft towards the dimer interface. HSQC and pulsed-field-gradient NMR diffusion experiments also show that gal-1 binds GRG with a gal-1:GRG stoichiometry of about 5:1 (or 6:1) and with average macroscopic and microscopic equilibrium dissociation constants (Kd) of 8 x 10(-6) M and 40 x 10(-6) M (or 48 x 10(-6) M) respectively, indicating stronger binding than to lactose (Kd=520 x 10(-6) M). Although gal-1 may bind GRG in various ways, the glycan can be competed for by lactose, suggesting that there is one major mode of interaction. Furthermore, even though terminal motifs on GRG are Gal-beta(1-->4)-Gal rather than the traditional Gal-beta(1-->4)-Glc/GlcNAc (where GlcNAc is N-acetylglucosamine), we show that the disaccharide Gal-beta(1-->4)-Gal can bind gal-1 at the lactose-binding domain. In addition, gal-1 binding to GRG disrupts inter-glycan interactions and decreases glycan-mediated solution viscosity, a glycan decongestion effect that may help explain why gal-1 promotes membrane fluidity and lateral diffusion of glycoconjugates within cell membranes. Overall, our results provide an insight into the function of galectin in situ and have potential significant biological consequences.

Dataset Information

Glycan dependence of Galectin-3 self-association properties.

Publications

Glycan dependence of Galectin-3 self-association properties.

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