In Silico Drug Design Targeting RNA Repeat Expansions - Project Summary. RNA orchestrates how critical biological functions are controlled, including catalysis, gene expression, enzymatic activities, and protein folding. Misregulation of gene expression cause dysregulation of RNA, which cause many heritable diseases such as Myotonic Dystrophy, Huntington’s disease, and Fragile X Syndrome caused by RNA transcripts that contain expanded repeats. The proposal seeks to create unique computational tools to investigate interaction of small molecules and ligands with dynamic RNA loops and to optimize lead compounds targeting RNA repeat expansions via inclusion of functional groups. Results will be used to facilitate drug design targeting RNA. Through a series of pilot studies, I have demonstrated how a more precise RNA force field improves the predictions. The objective of this proposal is to utilize this state-of-art RNA force field jointly with ever- increasing computational power to provide unique solutions in RNA-targeting pharmacotherapies. In Aim 1, a physics-based novel method will be created to predict the binding properties of small molecules targeting dynamic RNA loops. In Aim 2, I propose to develop a computational tool to optimize the binding properties of small molecules targeting RNA repeats via inclusion of functional groups. In Aim 3, design principles of artificial ligands targeting RNA repeats will be discovered using computational methods. This project will dramatically expand our understanding on how RNA loops fold and interact with small molecules and ligands. It will also have broader and potentially therapeutic implications for understanding RNA molecule interaction with other types of proteins such as the RNA-induced silencing complex, nucleic acid chaperones, and RNP complexes. This proposal takes advantage of a collaboration with Scripps Research Institute (Jupiter, FL). Furthermore, the research environment will provide numerous opportunities for career development of undergraduate and graduate students through national research presentations, collaborations, and training in the responsible conduct of research.