Binding Cooperativity Matters: A GM1-Like Ganglioside-Cholera Toxin B Subunit Binding Study Using a Nanocube-Based...

Area of Science:

• Biochemistry
• Biophysics
• Materials Science

Background:

• Protein-glycan recognition is crucial in biology and often involves multivalent binding.
• Cooperative interactions between glycans and binding subunits can complicate these recognition events.
• Understanding these complex interactions is key to deciphering biological processes.

Purpose of the Study:

• To develop a high-throughput method for quantitatively analyzing multivalent protein-glycan interactions.
• To investigate the binding of cholera toxin B subunit (CTB) to GM1 and fucosyl-GM1 gangliosides.
• To elucidate the role of binding cooperativity in dictating binding capacity and avidity.

Main Methods:

• Development of a nanocube-based lipid bilayer array for quantitative binding studies.
• Utilizing cholera toxin B subunit (CTB) as a model system for studying binding cooperativity.
• Employing a theoretical stepwise binding model to analyze CTB-glycan interactions.

Main Results:

• Confirmed positive cooperativity between CTB and GM1.
• Discovered that fucosyl-GM1 exhibits ~7 times higher CTB binding capacity than GM1, despite lower avidity.
• Observed that fucosyl-GM1 can activate GM2 receptors in a mixed system, enhancing overall binding capacity.

Conclusions:

• Binding cooperativity significantly influences multivalent protein-glycan interactions.
• The developed nanocube array provides a robust platform for dissecting complex binding mechanisms.
• Quantitative analysis of heterogeneous glycan systems is critical for understanding biological recognition.