Characterizing ligand-induced conformational changes in clinically relevant galectin-1 by H^N/H₂O (D₂O) exchange

Area of Science:

• Biochemistry
• Structural Biology
• Glycobiology

Background:

• Cellular glycans act as signals in physiological processes.
• Human galectin-1 (Gal-1) is involved in cell adhesion and growth regulation.
• Ligand binding to Gal-1 induces conformational changes, affecting its function.

Purpose of the Study:

• To investigate the structural alterations in Gal-1 upon lactose binding.
• To identify the specific regions of Gal-1 affected by ligand interaction.
• To correlate structural changes with Gal-1's biological roles.

Main Methods:

• Proton nuclear magnetic resonance (¹H NMR) spectroscopy for diffusion measurements.
• Hydrogen-deuterium exchange mass spectrometry (HDX-MS) to probe protein structure.
• Phase-modulated NMR clean chemical exchange (CLEANEX) NMR for high-resolution mapping.

Main Results:

• ¹H NMR detected ligand-induced changes in Gal-1's diffusion.
• HDX-MS revealed reduced proton exchange kinetics beyond the lactose-binding site.
• CLEANEX NMR mapped specific amino acid regions with increased protection from solvent exchange, indicating protein compaction.

Conclusions:

• Ligand binding induces significant structural changes in Gal-1, extending beyond the active site.
• These conformational alterations, particularly protein compaction, are crucial for Gal-1's cellular functions.
• The study provides a high-resolution map of Gal-1 structural changes upon ligand interaction.