Expression of nano-engineered RNA organelles in bacteria
Designing synthetic biomolecular condensates, or membrane-less organelles, offers insights on the functions of their natural counterparts, and is equally valuable for cellular and metabolic engineering. Choosing E. coli for its biotechnological relevance, we deploy RNA nanotechnology to design and express non-natural membrane-less organelles in vivo. The designer condensates assemble co-transcriptionally from branched RNA motifs interacting via base-pairing. Exploiting binding selectivity we express orthogonal, non-mixing condensates, and by embedding a protein-binding aptamer we achieve selective protein recruitment. Condensates can be made to dissolve and re-assemble upon thermal cycling, thereby reversibly releasing and re-capturing protein clients. The synthetic organelles are expressed robustly across the cell population and remain stable despite enzymatic RNA processing. Compared with existing solutions based on peptide building blocks or repetitive RNA sequences, these nanostructured RNA motifs enable algorithmic control over interactions, affinity for clients, and condensate microstructure, opening new directions in synthetic biology and biotechnology.