Epistructural tension promotes protein associations

Area of Science:

• Protein biophysics and structural biology.
• Thermodynamics of molecular interactions.
• Hydration dynamics at protein interfaces.

Background:

• Soluble protein structures possess an aqueous interface with associated energetic costs.
• Understanding hydration's role in protein interactions is crucial for molecular recognition.
• Existing models may not fully capture the energetic contributions of interfacial water.

Purpose of the Study:

• To define and quantify epistructural tension as a measure of protein hydration energetics.
• To identify protein residues that significantly contribute to epistructural tension.
• To elucidate the role of interfacial water in protein-protein binding hot spots.

Main Methods:

• Theoretical definition of epistructural tension based on reversible work per unit area.
• Analysis of free-energy costs associated with imperfect hydration at protein interfaces.
• Identification of binding hot spots by correlating residue contributions to epistructural tension.

Main Results:

• Epistructural tension is introduced as a parameter reflecting hydration free-energy costs.
• Residues contributing significantly to epistructural tension are identified as potential binding hot spots.
• Upon protein association, these key residues interact with or displace low-coordination water molecules.

Conclusions:

• Epistructural tension provides a valuable metric for assessing protein surface hydration.
• The concept highlights the energetic importance of specific water molecules at protein interfaces.
• This framework aids in understanding and predicting the energetics of protein-protein interactions and binding sites.