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Disentangling Glycan-Protein Interactions: Nuclear Magnetic Resonance (NMR) to the Rescue
Published on: May 17, 2024
Structure determination of a Galectin-3-carbohydrate complex using paramagnetism-based NMR constraints
Tiandi Zhuang1, Han-Seung Lee, Barbara Imperiali
1Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602, USA.
Protein Science : a Publication of the Protein Society
|April 17, 2008
Summary
This study introduces paramagnetism-based Nuclear Magnetic Resonance (NMR) constraints, including pseudo-contact shifts (PCS) and residual dipolar couplings (RDCs), to determine carbohydrate-protein complex structures. These methods overcome limitations of traditional NOEs for hydrogen-bonding ligands like lactose bound to Galectin-3.
Area of Science:
- Structural Biology
- Biophysics
- Nuclear Magnetic Resonance (NMR) Spectroscopy
Background:
- Determining ligand-protein complex structures is crucial for rational drug design.
- Traditional NMR methods like NOEs are often ineffective for carbohydrate ligands due to extensive hydrogen bonding.
- Alternative NMR observables are needed to accurately model carbohydrate-protein interactions.
Purpose of the Study:
- To demonstrate the utility of paramagnetism-based NMR constraints for structural determination of carbohydrate-protein complexes.
- To overcome the limitations of NOEs in studying systems with extensive hydrogen bonding.
- To accurately map the binding interface of Galectin-3 and lactose.
Main Methods:
- Integration of a lanthanide-binding peptide into the Galectin-3 C-terminus.
- Complexation with a dysprosium ion to introduce a paramagnetic center.
- Measurement of paramagnetism-based NMR observables: pseudo-contact shifts (PCS) and field-induced residual dipolar couplings (RDCs) for both protein and ligand.
Main Results:
- Successfully observed PCS and RDCs for the Galectin-3-lactose complex.
- These paramagnetic NMR constraints provided long-range and orientation-dependent information.
- The determined structure showed good agreement with existing crystal structures.
Conclusions:
- Paramagnetism-based NMR constraints are effective for characterizing carbohydrate-protein complexes, even with weak NOE signals.
- This approach enables accurate structural determination by leveraging PCS and RDCs.
- The method offers a valuable alternative for studying challenging ligand-protein interactions in structural biology.
