Saccharide binding by intelectins

Area of Science:

• Biochemistry
• Glycobiology
• Molecular Biology

Background:

• Human Intelectin-1 (hITLN1) previously showed affinity for microbial glycans with ribofuranoside or galactofuranoside residues.
• Crystal structures suggested hITLN1 distinguishes glycans via a terminal, acyclic 1,2-diol motif, present on galactofuranose.
• Discrepancies exist regarding hITLN1 saccharide ligand affinity across different assay formats.

Purpose of the Study:

• To investigate the ligand-binding properties of human Intelectin-1 (hITLN1) with a broader range of saccharides.
• To clarify the structural basis for hITLN1 saccharide recognition and reconcile conflicting binding data.
• To compare the saccharide binding profiles of hITLN1 homologues and assess cross-talk with protein ligands.

Main Methods:

• Affinity chromatography using Sepharose CL-6B to elute hITLN1 with various saccharide ligands.
• Analysis of saccharide structures, focusing on the presence or absence of a terminal, acyclic 1,2-diol.
• Comparative analysis of saccharide binding by hITLN1 homologues (HaloITLN, XL35ITLN) and assessment of mutual binding modulation with lactoferrin.

Main Results:

• hITLN1 was eluted by glycerol, glycerol derivatives, 2-deoxy-d-galactose, d-ribose, 2-deoxy-d-ribose, 2-C-hydroxymethyl-d-ribose, d-talose, d-idose, d-altrose, and sorbitol.
• Several identified ligands, including Sepharose and d-ribose, lack the previously proposed terminal, acyclic 1,2-diol motif.
• Distinct saccharide binding profiles were observed for HaloITLN and XL35ITLN, and hITLN1-saccharide binding modulated lactoferrin interaction.

Conclusions:

• hITLN1 exhibits broader saccharide binding specificity than previously suggested, extending beyond the 1,2-diol motif.
• Assay format significantly influences the observed affinity of saccharide ligands for hITLN1.
• hITLN1 homologues display unique binding characteristics, and ligand binding can involve complex cross-regulation with protein partners like lactoferrin.