Poster abstracts

Poster number 23 submitted by Qi Zhang

Elongated RNA (E-RNA): A New Approach to Study RNA Structural Dynamics

Qi Zhang (Department of Chemistry and Biophysics Research Division, University of Michigan), Hashim M. Al-Hashimi (Department of Chemistry and Biophysics Research Division, University of Michigan)

Abstract:
Resolving and characterizing internal motions based on NMR spin relaxation and residual dipolar couplings (RDCs) methods requires that internal motions are not correlated to overall reorientation. Here, we describe implementation of an elongation strategy which allowed us to decouple internal motions in ribonucleic acids (RNA) from overall reorientation. Application of spin relaxation and RDC methods revealed hierarchical motional modes spanning picosecond librations, nanosecond collective motions of A-form helical domains, and micro-to-millisecond structural transitions. Our results uncover a universe of internal motions occurring at nanosecond timescales that evade detection by conventional NMR spin relaxation methods because they occur at timescales approaching overall rotational diffusion. We present direct evidence that this uncovered network of motional modes code for functionally important changes in RNA conformation that allow adaptive recognition of chemically diverse targets.

The domain-elongation strategy provides a new approach for resolving motional modes in RNA spanning picosecond to millisecond timescales. Our results suggest that the adaptive changes in RNA conformation that take place upon ligand binding actually occur dynamically in the free RNA. Thus a manifold of internal motional modes codes for RNA adaptation.

Keywords: RNA dynamics, adaptive recognition, NMR