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Surface Electrostatics Govern the Emulsion Stability of Biomolecular Condensates.

Accepted version
Peer-reviewed

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Authors

Welsh, Timothy J 
Espinosa, Jorge R 
Joseph, Jerelle A 
Sridhar, Akshay 

Abstract

Liquid-liquid phase separation underlies the formation of biological condensates. Physically, such systems are microemulsions that in general have a propensity to fuse and coalesce; however, many condensates persist as independent droplets in the test tube and inside cells. This stability is crucial for their function, but the physicochemical mechanisms that control the emulsion stability of condensates remain poorly understood. Here, by combining single-condensate zeta potential measurements, optical microscopy, tweezer experiments, and multiscale molecular modeling, we investigate how the nanoscale forces that sustain condensates impact their stability against fusion. By comparing peptide-RNA (PR25:PolyU) and proteinaceous (FUS) condensates, we show that a higher condensate surface charge correlates with a lower fusion propensity. Moreover, measurements of single condensate zeta potentials reveal that such systems can constitute classically stable emulsions. Taken together, these results highlight the role of passive stabilization mechanisms in protecting biomolecular condensates against coalescence.

Description

Keywords

FUS, Liquid−liquid phase separation, colloid stability, microfluidics, zeta potential

Journal Title

Nano Letters: a journal dedicated to nanoscience and nanotechnology

Conference Name

Journal ISSN

1530-6984
1530-6992

Volume Title

Publisher

American Chemical Society
Sponsorship
European Research Council (337969)
Engineering and Physical Sciences Research Council (EP/P020259/1)
European Commission Horizon 2020 (H2020) Future and Emerging Technologies (FET) (766972)
European Research Council (803326)
European Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (841466)