Spontaneous driving forces give rise to protein−RNA condensates with coexisting phases and complex material properties

Abstract

Phase separation of multivalent protein and RNA molecules underlies the biogenesis of biomolecular condensates such as membraneless organelles. In vivo, these condensates encompass hundreds of distinct types of molecules that typically organize into multilayered structures supporting the differential partitioning of molecules into distinct regions with distinct material properties. The interplay between driven (active) versus spontaneous (passive) processes that are required for enabling the formation of condensates with coexisting layers of distinct material properties remains unclear. Here, we deploy systematic experiments and simulations based on coarse-grained models to show that the collective interactions among the simplest, biologically relevant proteins and archetypal RNA molecules are sufficient for driving the spontaneous emergence of multilayered condensates with distinct material properties. These studies yield a set of rules regarding homotypic and heterotypic interactions that are likely to be relevant for understanding the interplay between active and passive processes that control the formation of functional biomolecular condensates.

Cell‐Inspired All‐Aqueous Microfluidics: From Intracellular Liquid–Liquid Phase Separation toward Advanced Biomaterials

“…Therefore, to further reduce the dimension of the all‐aqueous droplets to sub‐micrometer size range and increase the generation frequency to orders of magnitude, new strategies have been proposed and investigated, such as nanofluidics and electric‐driven or light‐driven microfluidics . Moreover, the investigation of all‐aqueous emulsions in sub‐micrometer and nanometer size will bring new opportunities for fundamental studies at cellular or even subcellular level, such as the development of the protein/RNA‐based biological liquid coacervates for investigating organelle physics and physiology …”

Prebiotically-relevant low polyion multivalency can improve functionality of membraneless compartments

“…Coacervation with AMP held out even to (Arg)100, which can be understood in terms of strong cation-pi interactions possible for Arg-adenosine. 10,25,26 We then examined coacervate formation between cationic peptides, (Lys)n or (Arg)n , and anionic peptides, (Asp)n or (Glu)n , as a function of multivalency ( Fig. 2).…”

“…We attribute the surprisingly high salt stability of (Arg)10/nucleotide coacervates to cation-pi binding, which is known to be strong for Arg residues and adenosine nucleobases. 25,26,28 Early Earth conditions are thought to have encompassed a wide range of salt concentrations, from ponds to ocean water. 29,30 Our results indicate that even at just n=10, certain oligopeptidebased coacervates persist even above 1 M ionic strength, supporting the relevance of coacervatebased prebiotic compartments to diverse prebiotic scenarios extending beyond freshwater to brackish waters, oceans or submarine hydrothermal vent systems alike.…”

Dynamic Synthetic Cells Based on Liquid–Liquid Phase Separation

“…Dynamic substructures (vacuoles) have been observed within PLys/oligonucleotide coacervate microdroplets subjected to ac ontinuous electric field. [164] Although much work remains to be done in order to approach the structural complexity observed in biomolecular condensates,i ti sa nticipated that future experimental studies, together with theoretical modelling, will help understandinga nd dynamic control of multiphase organisation in synthetic LLPS, paving the way to the regulation of biochemical reactions through spatiotemporal control over the localisation of biomolecules. [126,127] Studies on ternary (or more) mixtures of phase-separating components are still relatively scarce.…”

“…[163] In anothere xample, spatially organised droplets with subcompartments were reportedi nR NA-protein systems via the rational design of RNA sequences and modulation of the interactions involved between components. [164] Although much work remains to be done in order to approach the structural complexity observed in biomolecular condensates,i ti sa nticipated that future experimental studies, together with theoretical modelling, will help understandinga nd dynamic control of multiphase organisation in synthetic LLPS, paving the way to the regulation of biochemical reactions through spatiotemporal control over the localisation of biomolecules.…”