Proteomic composition of eukaryotic and bacterial RNA decay condensates suggests convergent evolution.

Bacterial cells have a unique challenge to organize their cytoplasm without the use of membrane-bound organelles. Biomolecular condensates (henceforth BMCs) are a class of nonmembrane-bound organelles, which, through the physical process of phase separation, can form liquid-like droplets with proteins/nucleic acids. BMCs have been broadly characterized in eukaryotic cells, and BMCs have been recently identified in bacteria, with the first and best studied example being bacterial ribonucleoprotein bodies (BR-bodies). BR-bodies contain the RNA decay machinery and show functional parallels to eukaryotic P-bodies (PBs) and stress granules (SGs). Due to the finding that mRNA decay machinery is compartmentalized in BR-bodies and in eukaryotic PBs/SGs, we will explore the functional similarities in the proteins, which are known to enrich in these structures based on recent proteomic studies. Interestingly, despite the use of different mRNA decay and post-transcriptional regulatory machinery, this analysis has revealed evolutionary convergence in the classes of enriched enzymes in these structures.