Concordance of X‑ray and AlphaFold2 Models of SARS-CoV‑2 Main Protease with Residual Dipolar Couplings Measured in Solution

• Published in: Journal of the American Chemical Society Vol. 143; no. 46; pp. 19306 - 19310
• Main Authors: Robertson, Angus J, Courtney, Joseph M, Shen, Yang, Ying, Jinfa, Bax, Ad
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 24.11.2021
• Subjects: Catalytic Domain; Communication; Coronavirus 3C Proteases - chemistry; COVID-19; Crystallography, X-Ray - methods; Magnetic Resonance Spectroscopy; Molecular Conformation; Molecular Dynamics Simulation; Protein Conformation; Protein Folding; SARS-CoV-2; Software; X-Rays
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.1c10588

The 68-kDa homodimeric 3C-like protease of SARS-CoV-2, Mpro (3CLpro/Nsp5), is a promising antiviral drug target. We evaluate the concordance of models generated by the newly introduced AlphaFold2 structure prediction program with residual dipolar couplings (RDCs) measured in solution for 15N–1HN and 13C′–1HN atom pairs. The latter were measured using a new, highly precise TROSY-AntiTROSY Encoded RDC (TATER) experiment. Three sets of AlphaFold2 models were evaluated: (1) Mpro AF, generated using the standard AlphaFold2 input structural database; (2) Mpro AFD, where the AlphaFold2 implementation was modified to exclude all candidate template X-ray structures deposited after Jan 1, 2020; and (3) Mpro AFS, which excluded all structures homologous to coronaviral Mpro. Close agreement between all three sets of AlphaFold models and experimental RDC data is found for most of the protein. For residues in well-defined secondary structure, the agreement decreases somewhat upon Amber relaxation. For these regions, Mpro AF agreement exceeds that of most high-resolution X-ray structures. Residues from domain 2 that comprise elements of both the active site and the homo-dimerization interface fit less well across all structures. These results indicate novel opportunities for combining experimentation with molecular dynamics simulations, where solution RDCs provide highly precise input for QM/MM simulations of substrate binding/reaction trajectories.