Binding free energy analysis of protein-protein docking model structures by evERdock

Area of Science:

• Computational Biology
• Structural Biology
• Biophysics

Background:

• Protein-protein interactions are crucial for cellular functions.
• Accurate modeling of protein complex structures is essential for understanding biological mechanisms.
• Evaluating the quality of predicted protein complex models (decoys) remains a challenge.

Purpose of the Study:

• To assess the efficacy of the evERdock method for evaluating protein-protein complex decoys.
• To identify potential areas for improvement in protein-protein interface modeling.
• To investigate the role of interfacial water and solute entropy in binding free energy calculations.

Main Methods:

• Application of the evERdock method, combining molecular dynamics simulations with energy representation (ER) theory.
• Analysis of 100-300 model structures for four protein-protein complexes.
• Evaluation of interface properties including native contacts, hydrogen bonds, and salt bridges.
• Optimization of interfacial interactions by including water molecules.

Main Results:

• evERdock successfully identified near-native decoys and crystal structures as having the lowest binding free energies.
• Decoys with low interface root-mean-square distance but high binding free energy were found to have insufficiently optimized interfaces.
• Optimizing interfacial interactions, including water molecules, improved the binding free energies of these decoys.
• Inclusion of solute entropy did not consistently improve decoy evaluation.

Conclusions:

• The evERdock method is effective for evaluating protein-protein complex decoys.
• Interface optimization, particularly involving water molecules, is critical for accurate binding free energy prediction.
• Further refinement of computational methods is needed to fully capture the complexities of protein-protein binding.