Talk abstracts
Talk on Saturday 03:30-03:45pm submitted by Raghav Poudyal
Sequence and structure control assembly of RNA condensates
Raghav Poudyal (Chemistry, Pennsylvania State University), Jacob Sieg (Chemistry, Pennsylvania State University), Bede Portz (School of Medicine, University of Pennsylvania), Christine Keating (Chemistry, Pennsylvania State University), Philip Bevilacqua (Chemistry, Pennsylvania State University)
Abstract:
Intracellular condensates formed through liquid-liquid phase (LLPS) primarily contain proteins and RNA among other biomolecules. Recent evidences point to tremendous contributions of RNA self-assembly in formation of intracellular condensates. As a majority of previous studies on LLPS have focused on protein biochemistry, how biological RNAs affect LLPS remain unexplored. In this study, we explore the effects of crowding, metal ions, and RNA structure towards formation of condensates that are largely composed of RNAs. Using bacterial riboswitches as a model system, we first demonstrate that LLPS of RNA is promoted by molecular crowding, as evidenced by the formation of RNA droplets in the presence of polyethylene glycol. In the absence of crowders, elevated Mg2+ concentrations promoted assembly of specific riboswitches. In silico prediction identified key structural and sequence elements that potentiate the formation of condensates; these predictions were corroborated by experimental observations. We implement structure-guided designs to generate condensates with novel functions. Finally, we show that RNA condensates protect RNAs from nucleases, suggesting potential biological roles for such higher-order RNA assemblies. Overall, our work provides mechanistic insights on contributions of both intrinsic RNA properties and extrinsic environmental conditions that promote the formation and regulation of condensates composed of RNAs.
Keywords: RNA structure, phase separation, riboswitch