Identifying and overcoming the sampling challenges in relative binding free energy calculations of a model protein:protein complex Journal Article


Authors: Zhang, I.; Rufa, D. A.; Pulido, I.; Henry, M. M.; Rosen, L. E.; Hauser, K.; Singh, S.; Chodera, J. D.
Article Title: Identifying and overcoming the sampling challenges in relative binding free energy calculations of a model protein:protein complex
Abstract: Relative alchemical binding free energy calculations are routinely used in drug discovery projects to optimize the affinity of small molecules for their drug targets. Alchemical methods can also be used to estimate the impact of amino acid mutations on protein:protein binding affinities, but these calculations can involve sampling challenges due to the complex networks of protein and water interactions frequently present in protein:protein interfaces. We investigate these challenges by extending a graphics processing unit (GPU)-accelerated open-source relative free energy calculation package (Perses) to predict the impact of amino acid mutations on protein:protein binding. Using the well-characterized model system barnase:barstar, we describe analyses for identifying and characterizing sampling problems in protein:protein relative free energy calculations. We find that mutations with sampling problems often involve charge-changes, and inadequate sampling can be attributed to slow degrees of freedom that are mutation-specific. We also explore the accuracy and efficiency of current state-of-the-art approaches─alchemical replica exchange and alchemical replica exchange with solute tempering─for overcoming relevant sampling problems. By employing sufficiently long simulations, we achieve accurate predictions (RMSE 1.61, 95% CI: [1.12, 2.11] kcal/mol), with 86% of estimates within 1 kcal/mol of the experimentally determined relative binding free energies and 100% of predictions correctly classifying the sign of the changes in binding free energies. Ultimately, we provide a model workflow for applying protein mutation free energy calculations to protein:protein complexes, and importantly, catalog the sampling challenges associated with these types of alchemical transformations. Our free open-source package (Perses) is based on OpenMM and is available at https://github.com/choderalab/perses. © 2023 American Chemical Society
Keywords: molecular dynamics; protein binding; amino acid; thermodynamics; amino acids; molecular dynamics simulation; entropy
Journal Title: Journal of Chemical Theory and Computation
Volume: 19
Issue: 15
ISSN: 1549-9618
Publisher: American Chemical Society  
Date Published: 2023-08-08
Start Page: 4863
End Page: 4882
Language: English
DOI: 10.1021/acs.jctc.3c00333
PUBMED: 37450482
PROVIDER: scopus
PMCID: PMC11219094
DOI/URL:
Notes: Article -- Erratum issued, see DOI: 10.1021/acs.jctc.3c01298 -- MSK Cancer Center Support Grant (P30 CA008748) acknowledged in PDF -- MSK corresponding author are Sukrit Singh and John Chodera --Source: Scopus
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MSK Authors
  1. John Damon Chodera
    120 Chodera
  2. Ivy Zhang
    7 Zhang
  3. Dominic Antonio Rufa
    4 Rufa
  4. Mike Henry
    7 Henry
  5. Sukrit Singh
    10 Singh