show Abstracthide AbstractRNA is emerging as a valuable target for the development of novel therapeutic agents. The rational design of RNA-targeting small molecules, however, has been hampered by the relative lack of methods for the analysis of small molecule-RNA interactions. Here we present our efforts to develop such a platform using photoaffinity labeling. This technique, termed Photoaffinity Evaluation of RNA Ligation-Sequencing (PEARL-seq), enables the rapid identification of small molecule binding locations within their RNA targets and can provide information on ligand selectivity across multiple different RNAs. These data, when supplemented with small molecule SAR data and RNA probing data enables the construction of a computational model of the RNA-ligand structure, thereby enabling the rational design of novel RNA-targeted ligands. Overall design: PEARL-seq, SHAPE-MaP and DMS-MaP analysis of the model RNA Aptamer21