Designer membraneless organelles enable codon reassignment of selected mRNAs in eukaryotes

Abstract

Nature regulates interference between cellular processes—allowing more complexity of life—by confining specific functions to organelles. Inspired by this concept, we designed an artificial organelle dedicated to protein engineering. We generated a membraneless organelle to translate only one type of messenger RNA—by recruiting an RNA-targeting system, stop codon–suppression machinery, and ribosomes—by means of phase separation and spatial targeting. This enables site-specific protein engineering with a tailored noncanonical function in response to one specific codon in the entire genome only in the protein of choice. Our results demonstrate a simple yet effective approach to the generation of artificial organelles that provides a route toward customized orthogonal translation and protein engineering in semisynthetic eukaryotic cells.