Allostery at a Protein-Protein Interface Harboring an Intermolecular Motional Network

Motional properties of proteins govern recognition, catalysis, and regulation. The dynamics of tightly interacting residues can form intramolecular dynamic networks, dependencies fine-tuned by evolution to optimize a plethora of functional aspects. The constructive interaction of residues from different proteins to assemble intermolecular dynamic networks is a similarly likely case but has escaped thorough experimental assessment due to interfering association/dissociation dynamics. Here, we use fast-MAS solid-state 15N R1 rho NMR relaxation dispersion aided by molecular-dynamics simulations to mechanistically assess the hierarchy of individual mu s timescale motions arising from a crystal-crystal contact, in the absence of translational motion. In contrast to the monomer, where particular mutations entail isolated perturbations, specific intermolecular interactions couple the motional properties between distant residues in the same protein. The mechanistic insights obtained from this conceptual work may improve our understanding on how intramolecular allostery can be tuned by intermolecular interactions via assembly of dynamic networks from previously isolated elements. Intramolecular dynamic networks allow for regulation of protein function by dynamic allostery, but it has been unclear whether such networks can be positively modulated through protein-protein association. It is now shown that the formation of a protein-protein interface can motionally couple distant sites, turning preexisting structures into functional networks. image