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Thermodynamics and kinetics of phase separation of protein-RNA mixtures by a minimal model.

Accepted version
Peer-reviewed

Type

Article

Change log

Authors

Joseph, Jerelle A 
Espinosa, Jorge R 
Sanchez-Burgos, Ignacio 
Garaizar, Adiran 

Abstract

Intracellular liquid-liquid phase separation enables the formation of biomolecular condensates, such as ribonucleoprotein granules, which play a crucial role in the spatiotemporal organization of biomolecules (e.g., proteins and RNAs). Here, we introduce a patchy-particle polymer model to investigate liquid-liquid phase separation of protein-RNA mixtures. We demonstrate that at low to moderate concentrations, RNA enhances the stability of RNA-binding protein condensates because it increases the molecular connectivity of the condensed-liquid phase. Importantly, we find that RNA can also accelerate the nucleation stage of phase separation. Additionally, we assess how the capacity of RNA to increase the stability of condensates is modulated by the relative protein-protein/protein-RNA binding strengths. We find that phase separation and multiphase organization of multicomponent condensates is favored when the RNA binds with higher affinity to the lower-valency proteins in the mixture than to the cognate higher-valency proteins. Collectively, our results shed light on the roles of RNA in ribonucleoprotein granule formation and the internal structuring of stress granules.

Description

Keywords

Kinetics, Organelles, RNA, RNA-Binding Proteins, Thermodynamics

Journal Title

Biophys J

Conference Name

Journal ISSN

0006-3495
1542-0086

Volume Title

120

Publisher

Elsevier BV
Sponsorship
Engineering and Physical Sciences Research Council (EP/N509620/1)
Engineering and Physical Sciences Research Council (EP/P020259/1)
European Research Council (803326)
EPSRC (EP/T517847/1)
Engineering and Physical Sciences Research Council (EPSRC) scholarship to Ignacio Sanchez-Burgos