Co-transcriptional production of programmable RNA condensates and synthetic organelles

Condensation of RNA and proteins is central to cellular functions, and the ability to program it would be valuable in synthetic biology and synthetic cell science. Here we introduce a modular platform for engineering synthetic RNA condensates from tailor-made, branched RNA nanostructures that fold and assemble co-transcriptionally. Up to three orthogonal condensates can form simultaneously and selectively accumulate guest molecules. The RNA condensates can be expressed within synthetic cells to produce membrane-less organelles with controlled number, size, morphology and compositions, and that display the ability to selectively capture proteins. The in situ expression of programmable RNA condensates could underpin spatial organisation of functionalities in both biological and synthetic cells. ### 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