Structural insights into the ATP-dependent activation of NOD-like receptor with pyrin 3 (NLRP3) protein by molecular dynamics simulation.

The inflammasome-forming NOD-like receptor containing pyrin-3 (NLRP3) protein is a critical player in the innate immune responses to cellular danger signals. New structural data of NLRP3 provide a framework to probe the conformational impact of nucleotide binding. In this study, microsecond molecular dynamics (MD) simulations were used to detail information on the unique structural conformations adopted by NLRP3 with ATP or ADP binding. Sampling convergence reflected a high degree of confidence in the MD simulations as shown by RMSD and protein-nucleotide concordance, favourable overall MM-PBSA ligand binding energies for both nucleotides and low cosine coefficients of the principal eigenvectors obtained with essential dynamics (ED) analysis. NLRP3-ADP simulations provide relatively stable conformations with few global rearrangements as shown by decreased protein RMSD, Rg, SASA, and solvent accessibility for the ADP-bound structure. In contrast, ATP binding induced increased flexibility and resulted in substantive conformational changes to the NLRP3 structure. Binding of ATP was thermodynamically favourable as shown by the ΔG and MM-PBSA calculations of complex free energies, and these NLRP3-ATP simulations resulted in similar structural transitions as observed in the activated NLRC4 empirical structure. Lastly, the active conformation of NLRP3 critically depends on hinging between the HD2 and LRR domains, whereby ATP binding drives local conformational changes that are conveyed to the global structure.