Dynamical Cooperativity of Ligand-Residue Interactions Evaluated with the Fragment Molecular Orbital Method

By the splendid advance in computation power realized with Fugaku supercomputer, it has become possible to perform ab initio fragment molecular orbital (FMO) calculations for thousands of dynamical structures of a protein-ligand complex in a parallelized way. We have thus carried out the electron-correlated FMO calculations for a complex of the 3C-like (3CL) main protease (Mpro) of the new coronavirus (SARS-CoV-2) and its inhibitor N3 incorporating the structural fluctuations sampled by classical molecular dynamics (MD) simulation in hydrated condition. Along with a statistical evaluation of inter-fragment interaction energies (IFIEs) between the N3 ligand and surrounding amino-acid residues for a thousand of dynamical structure samples, we have applied in this study a novel approach based on the principal component analysis (PCA) and the singular value decomposition (SVD) to the analysis of IFIE data in order to extract the dynamically cooperative interactions between the ligand and residues. We have found that the relative importance of each residue is modified via the structural fluctuations and that the ligand is bound in the pharmacophore in a dynamical manner through collective interactions formed by multiple residues, thus providing a new insight into structure-based drug discovery