# Expression of nano-engineered RNA organelles in bacteria

## TL;DR

Scientists created synthetic RNA-based organelles in bacteria that can control protein interactions and respond to temperature changes.

## Contribution

The study introduces RNA nanotechnology to build functional, orthogonal membraneless organelles in E. coli with controllable protein recruitment.

## Key findings

- RNA-based condensates assemble co-transcriptionally and remain stable in E. coli.
- Condensates can dissolve and reassemble upon thermal cycling, enabling reversible protein capture.
- The design allows orthogonal, non-mixing organelles with selective protein binding.

## Abstract

Designing synthetic biomolecular condensates, or membraneless organelles, offers insights into 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 membraneless 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 reassemble 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 further directions in synthetic biology and biotechnology.

Designing synthetic biomolecular condensates offers biological insights and is valuable for cellular and metabolic engineering. Here, the authors express orthogonal, unnatural condensates with protein binding aptamers in E. coli, which can dissolve and reassemble upon thermal cycling.