Integrating Conformational Dynamics and Perturbation-Based Network Modeling for Mutational Profiling of Binding and Allostery in the SARS-CoV-2 Spike Variant Complexes with Antibodies: Balancing Local and Global Determinants of Mutational Escape Mechanisms

Abstract

In this study, we combined all-atom MD simulations, the ensemble-based mutational scanning of protein stability and binding, and perturbation-based network profiling of allosteric interactions in the SARS-Cov-2 Spike complexes with a panel of cross-reactive and ultra-potent single antibodies (B1-182.1 and A23-58.1) as well as antibody combinations (A19-61.1/B1-182.1 and A19-46.1/B1-182.1). Using this approach, we quantify local and global effects of mutations in the complexes, identify structural stability centers, characterize binding energy hotspots and predict the allosteric control points of long-range interactions and communications. Conformational dynamics and distance fluctuation analysis revealed the antibody-specific structural stability signatures of the spike complexes that can dictate the pattern of mutational escape. By employing an integrated analysis of conformational dynamics and binding energetics, we found that the potent antibodies that efficiently neutralize Omicron spike variant can form the dominant binding energy hotpots with the conserved stability centers in which mutations may be restricted by the requirements of the folding stability and binding to the host receptor. The results show that protein stability and binding energetics of the SARS-CoV-2 spike complexes with the panel of cross-reactive ultrapotent antibodies are tolerant to the constellation of Omicron mutations. A network-based perturbation approach for mutational profiling of allosteric residues potentials revealed how antibody binding can modulate allosteric interactions and identified allosteric control points that can form vulnerable sites for mutational escape. This study suggested a mechanism in which the pattern of specific escape mutants for ultrapotent antibodies may not be solely determined by the binding interaction changes but are driven by a complex balance and tradeoffs between different local and global factors including the impact of mutations on structural stability, binding strength, long-range interactions and fidelity of allosteric signaling.