Binding Thermodynamics to Intrinsically Disordered Protein Domains

Area of Science:

• Biochemistry
• Structural Biology
• Molecular Interactions

Background:

• Many proteins contain intrinsically disordered regions (IDRs) that participate in crucial binding interactions.
• Binding to IDRs often necessitates a transition from disordered to ordered states, coupling binding with folding.
• The thermodynamics of these coupled events are critical for understanding protein function.

Purpose of the Study:

• To differentiate the thermodynamic profiles of binding coupled to folding versus binding independent of folding in the same protein.
• To provide a protocol for analyzing these distinct binding mechanisms.
• To use the HIV-1 envelope glycoprotein gp120 as a model system.

Main Methods:

• Investigating the binding thermodynamics of intrinsically disordered protein domains.
• Comparing binding events that induce protein structuring with those that do not.
• Utilizing the HIV-1 envelope glycoprotein gp120 and its binding partners (CD4, MAb 17b, MAb b12).

Main Results:

• Demonstrated distinct thermodynamic signatures for binding coupled to folding versus binding independent of folding.
• Showcased how different ligands binding to gp120 elicit varied structural responses and thermodynamic outcomes.
• Highlighted the role of protein structure dynamics in molecular recognition.

Conclusions:

• The thermodynamic analysis of protein-ligand interactions must account for whether binding is coupled to folding.
• Understanding these differences is crucial for characterizing the function of intrinsically disordered proteins.
• This approach provides insights into the mechanisms of viral glycoproteins like gp120.