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Bioinformatics Resources for the Study of Glycan-Mediated Protein Interactions
Published on: January 20, 2022
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Macromolecular assemblies of complex polysaccharides with galectin-3 and their synergistic effects on function
Tao Zhang1, Michelle C Miller2, Yi Zheng1
1Jilin Province Key Laboratory for Chemistry and Biology of Natural Drugs in Changbai Mountain, School of Life Sciences, Northeast Normal University, Changchun 130024, PR China.
The Biochemical Journal
|October 8, 2017
Summary
Pectin polysaccharides like rhamnogalacturonan (RG) and homogalacturonans (HGs) bind to galectin-3 (Gal-3). Their combined action enhances Gal-3 binding, offering insights into drug development and protein-polysaccharide interactions.
Area of Science:
- Carbohydrate chemistry
- Structural biology
- Immunology
Background:
- Pectin-derived polysaccharides can modulate galectin functions in diseases.
- Understanding these interactions is crucial for developing pectin-based therapeutics.
- Complex polysaccharides serve as models for studying protein-polysaccharide interactions.
Purpose of the Study:
- To investigate the binding interactions between galectin-3 (Gal-3) and specific pectin-derived polysaccharides: rhamnogalacturonan (RG) and two homogalacturonans (HGs).
- To elucidate the binding mechanism and the functional consequences of these interactions.
Main Methods:
- BioLayer Interferometry (BLI) to determine binding affinities (apparent KD).
- Fluorescence-linked immunosorbent assays (FLISA) to assess binding.
- Nuclear Magnetic Resonance (NMR) spectroscopy (15N-1H and 13C-1H HSQC) to identify interaction sites.
- Polysaccharide particle size measurements.
Main Results:
- RG, HG1, and HG2 bind Gal-3 with apparent KD values of 49 nM, 46 µM, and 138 µM, respectively.
- NMR studies indicate primary interaction with the F-face of the Gal-3 carbohydrate recognition domain.
- Individual polysaccharides showed limited inhibition of Gal-3-mediated T-cell apoptosis and hemagglutination.
- Combinations of RG and HG polysaccharides exhibited synergistic increases in activity and avidity for Gal-3.
- Evidence suggests HG interacts with RG, potentially exposing more binding sites on RG for Gal-3.
Conclusions:
- Pectin-derived RG and HG polysaccharides interact with Gal-3, primarily at its carbohydrate recognition domain.
- The synergistic activity of RG and HG mixtures suggests cooperative binding mechanisms.
- This study provides a model for HG-RG interaction, enhancing RG avidity for Gal-3.
- Findings contribute to understanding complex polysaccharide-protein interactions and inform potential therapeutic strategies targeting galectins.
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