Ortsaufgelöste Festkörper-NMR-Studien am “Trigger-Faktor” im Komplex mit der großen ribosomalen 50S-Untereinheit

Site-Specific Studies of Nucleosome Interactions by Solid-State NMR Spectroscopy

Chromatin function depends on a dense network of interactions between nucleosomes and a wide range of proteins. A detailed description of these protein-nucleosome interactions is required to reach a full molecular understanding of chromatin function in both genetics and epigenetics. Herein, we show that the structure, dynamics, and interactions of nucleosomes can be interrogated in a residue-specific manner by using state-of-the-art solid-state NMR spectroscopy. Using sedimented nucleosomes, high-resolution spectra were obtained for both flexible histone tails and the non-mobile histone core. Through co-sedimentation of a nucleosome-binding peptide, we demonstrate that protein-binding sites on the nucleosome surface can be determined. We believe that this approach holds great promise as it is generally applicable, extendable to include the structure and dynamics of the bound proteins, and scalable to interactions of proteins with higher-order chromatin structures, including isolated and cellular chromatin.

Microsecond Timescale Protein Dynamics: a Combined Solid-State NMR Approach

Conformational exchange in proteins is a major determinant in protein functionality. In particular, the μs-ms timescale is associated with enzymatic activity and interactions between biological molecules. We show here that a comprehensive data set of R1ρ relaxation dispersion profiles employing multiple effective fields and tilt angles can be easily obtained in perdeuterated, partly back-exchanged proteins at fast magic-angle spinning and further complemented with chemical-exchange saturation transfer NMR experiments. The approach exploits complementary sources of information and enables the extraction of multiple exchange parameters for μs-ms timescale conformational exchange, most notably including the sign of the chemical shift differences between the ground and excited states.

Intermolecular Interactions and Protein Dynamics by Solid-State NMR Spectroscopy

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.

Intermolecular Interactions and Protein Dynamics by Solid-State NMR Spectroscopy

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 (15) N 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.