Modular RNA motifs for orthogonal phase separated compartments

Recent discoveries in biology have highlighted the importance of protein and RNA-based condensates as an alternative to classical membrane-bound organelles for the task of compartmentalizing molecules and biochemical reactions. Here, we demonstrate the rational design of pure RNA condensates from star-shaped RNA motifs. We generate condensates using two different RNA nanostar architectures: multi-stranded nanostars whose binding interactions are programmed via single-stranded overhangs, and single-stranded nanostars whose interactions are programmed via kissing loops. Through rational design of the nanostar interaction sequences, we demonstrate that both architectures can produce orthogonal (distinct and immiscible) condensates, which can be individually tracked via fluorogenic aptamers. We also show that aptamers make it possible to recruit peptides and proteins to the condensates with high specificity. Successful cotranscriptional formation of condensates from single-stranded nanostars suggests that they may be genetically encoded and produced in living cells. We provide a library of orthogonal RNA condensates that can be modularly customized and offer a route toward creating systems of functional artificial organelles. ### Competing Interest Statement The Regents of University of California has filed a patent application in the U.S. Patent and Trademark Office which includes disclosure of inventions described in this manuscript, Provisional Application Serial No. 63/588,142, filed on October 5, 2023, and entitled: SINGLE STRANDED RNA MOTIFS FOR IN VITRO COTRANSCRIPTIONAL PRODUCTION OF ORTHOGONAL PHASE SEPARATED CONDENSATES.