A Thermodynamic Model for Multivalency in 14-3-3 Protein-Protein Interactions

Area of Science:

• Biochemistry
• Molecular Biology
• Chemical Thermodynamics

Background:

• Protein-protein interactions (PPIs) are crucial for cellular functions.
• Multivalency in PPIs, involving multiple binding sites, presents complex challenges in understanding cellular control and developing therapeutics.
• Existing thermodynamic models often lack the capacity to fully describe multivalent interactions.

Purpose of the Study:

• To establish a thermodynamic binding model for multivalent PPIs using effective molarity as a key parameter.
• To investigate the binding thermodynamics of the bivalent 14-3-3 protein scaffold with nonavalent CFTR and hexavalent LRRK2 proteins.
• To analyze the contribution of individual binding sites to overall affinity and predict the impact of site modulation.

Main Methods:

• Development of a thermodynamic model based on ditopic host-guest systems.
• Characterization of effective molarity as a parameter for intramolecular binding in divalent interactions.
• Experimental determination of binding thermodynamics for 14-3-3 with CFTR and LRRK2.
• Computational simulations of protein-protein binding speciations.

Main Results:

• The model successfully describes multivalent PPIs, highlighting the role of effective molarity.
• Enthalpy-entropy correlation was observed in both the CFTR-14-3-3 and LRRK2-14-3-3 systems.
• Simulations showed that CFTR binding to 14-3-3 involves multiple sites, with adaptability upon removal of the strongest site.
• LRRK2 binding is dominated by two sites, but a third site also contributes to complex formation.

Conclusions:

• Thermodynamic modeling provides a framework for analyzing and predicting the behavior of multivalent PPIs.
• Understanding the contribution of individual sites in multivalent interactions is key for modulating PPIs.
• PPI stabilization emerges as a promising strategy for drug discovery targeting multivalent interactions in diseases.