Electrostatic contribution to the binding stability of protein-protein complexes

Area of Science:

• Biophysics
• Computational Biology
• Protein Science

Background:

• Protein-protein interactions are crucial for biological processes.
• Understanding the forces governing protein binding stability is essential for drug design and protein engineering.
• Electrostatic interactions are hypothesized to play a significant role in protein binding stability.

Purpose of the Study:

• To investigate the role of electrostatic interactions in protein binding stability.
• To compare the accuracy of different Poisson-Boltzmann model protocols for predicting binding stability changes due to mutations.
• To evaluate the contribution of electrostatic forces versus other factors like van der Waals and hydrophobic interactions.

Main Methods:

• Performed electrostatic calculations on 64 mutations across six protein-protein complexes.
• Tested three Poisson-Boltzmann model protocols: vdW4, SE4, and SE20, varying dielectric boundary definitions and protein dielectric constants.
• Compared computational predictions with experimental data for binding stability.

Main Results:

• The vdW4 protocol, defining the dielectric boundary at the van der Waals surface with a dielectric constant of 4, showed the closest agreement with experimental data.
• Results align with previous findings on the barnase-barstar complex.
• While electrostatic contributions appear dominant, discrepancies highlight the importance of van der Waals and hydrophobic interactions.

Conclusions:

• The vdW4 model is a reliable approach for estimating electrostatic contributions to protein binding stability.
• Electrostatic interactions are significant drivers of binding stability for the studied mutations.
• Future refinements should incorporate nonelectrostatic effects for more comprehensive predictions.