Visualizing RNA Conformational Changes via Pattern Recognition of RNA by Small Molecules.

Conformational changes in RNA play vital roles in the regulation of many biological systems, yet these changes can be challenging to visualize. Previously, we demonstrated that Pattern Recognition of RNA by Small Molecules (PRRSM) can unbiasedly cluster defined RNA secondary structure motifs utilizing an aminoglycoside receptor library. In this work, we demonstrate the power of this method to visualize changes in folding at the secondary structure level within two distinct riboswitch structures. After labeling at three independent positions on each riboswitch, PRRSM accurately classified all apo and ligand-bound riboswitch structures, including changes in the size of a structural motif, and revealed modification sites that prevented folding and/or led to a mixture of states. These data underscore the utility and robustness of the PRRSM assay for rapid assessment of RNA structural changes and for gaining ready insight into nucleotide positions critical to RNA folding.