Intermolecular Interactions and Protein Dynamics by Solid-State NMR Spectroscopy

Abstract

Understanding the dynamics of interacting proteins is a crucial step toward describing many biophysical processes. Here we investigate the backbone dynamics for protein GB1 in two different assemblies: crystalline GB1 and the precipitated GB1-antibody complex with a molecular weight of more than 300 kDa. We perform these measurements on samples containing as little as eight nanomoles of GB1. From measurements of site-specific 15N relaxation rates including relaxation dispersion we obtain snapshots of dynamics spanning nine orders of magnitude in terms of the time scale. A comparison of measurements for GB1 in either environment reveals that while many of the dynamic features of the protein are conserved between them (in particular for the fast picosecond-nanosecond motions), much greater differences occur for slow motions with motions in the >500 ns range being more prevalent in the complex. The data suggest that GB1 can potentially undergo a small-amplitude overall anisotropic motion sampling the interaction interface in the complex. Protein dynamics: To investigate the influence of different intermolecular interactions on the protein dynamics extensive widespread site-specific 15N relaxation measurements were compared for a protein GB1 in a crystal and in an antibody complex with a molecular weight of more than 300 kDa (see picture). The proposed approach allows to directly access dynamics of a protein in large protein complexes.