Decoding Galectin-Glycan Recognition with ¹⁹F-Tagged Lectins: from Simple Glycans to the Cellular Glycocalyx

Area of Science:

• Cell biology
• Biochemistry
• Molecular interactions

Background:

• Glycan-lectin interactions are vital for cell surface processes but difficult to study at the molecular level.
• Heterogeneous glycosylation and overlapping lectin specificities complicate understanding of competitive binding and selective recognition.

Purpose of the Study:

• To develop and apply a novel NMR-based method, 19F lectin tagging, for characterizing complex glycan-lectin binding events.
• To investigate the competitive binding behavior of galectins with varying target complexities, from carbohydrates to the cell surface glycocalyx.

Main Methods:

• Introduction of 19F probes into lectins to generate simple, background-free NMR spectra.
• Application of 19F lectin tagging to study binding in complex biological environments, including cell surfaces.
• Analysis of lectin mixtures with overlapping specificities to resolve individual binding behaviors.

Main Results:

• 19F lectin tagging enables facile binding studies in complex biological systems.
• The method successfully resolved competitive binding among galectins with overlapping specificities.
• Galectin specificity is influenced by glycan presentation, multivalency, and competition, not just LacNAc recognition.

Conclusions:

• 19F lectin tagging is a powerful tool for investigating glycan-mediated binding events in biologically relevant systems.
• Galectin recognition of targets like TIM-3 is context-dependent, involving competitive interactions at the cell surface.
• This approach offers new insights into the molecular mechanisms of cell surface recognition and immune regulation.