Biomolecular condensates - extant relics or evolving microcompartments?

Unprecedented discoveries during the past decade have unearthed the ubiquitous presence of biomolecular condensates (BCs) in diverse organisms and their involvement in a plethora of biological functions. A predominant number of BCs involve coacervation of RNA and proteins that demix from homogenous solutions by a process of phase separation well described by liquid-liquid phase separation (LLPS), which results in a phase with higher concentration and density from the bulk solution. BCs provide a simple and effective means to achieve reversible spatiotemporal control of cellular processes and adaptation to environmental stimuli in an energy-independent manner. The journey into the past of this phenomenon provides clues to the evolutionary origins of life itself. Here I assemble some current and historic discoveries on LLPS to contemplate whether BCs are extant biological hubs or evolving microcompartments. I conclude that BCs in biology could be extant as a phenomenon but are co-evolving as functionally and compositionally complex microcompartments in cells alongside the membrane-bound organelles. This Perspective discusses how biomolecular condensates are co-evolving as complex microcompartments alongside membrane-bound organelles in cells.

Automated summary

Unprecedented discoveries have revealed the presence of biomolecular condensates (BCs) in diverse organisms and their involvement in biological functions. Most BCs involve the coacervation of RNA and proteins through liquid-liquid phase separation (LLPS), providing a means for reversible spatiotemporal control of cellular processes. This Perspective discusses the co-evolution of BCs as complex microcompartments alongside membrane-bound organelles in cells.