Details

Autor(en) / Beteiligte

• van Haren, Merlijn H. I.
• Visser, Brent S.
• Spruijt, Evan

Titel

Probing the surface charge of condensates using microelectrophoresis

Ist Teil von

• Nature communications, 2024-04, Vol.15 (1), p.3564-3564, Article 3564

Ort / Verlag

London: Nature Publishing Group UK

Erscheinungsjahr

2024

Quelle

MEDLINE

Beschreibungen/Notizen

• Biomolecular condensates play an important role in cellular organization. Coacervates are commonly used models that mimic the physicochemical properties of biomolecular condensates. The surface of condensates plays a key role in governing molecular exchange between condensates, accumulation of species at the interface, and the stability of condensates against coalescence. However, most important surface properties, including the surface charge and zeta potential, remain poorly characterized and understood. The zeta potential of coacervates is often measured using laser doppler electrophoresis, which assumes a size-independent electrophoretic mobility. Here, we show that this assumption is incorrect for liquid-like condensates and present an alternative method to study the electrophoretic mobility of coacervates and in vitro condensate models by microelectrophoresis and single-particle tracking. Coacervates have a size-dependent electrophoretic mobility, originating from their fluid nature, from which a well-defined zeta potential is calculated. Interestingly, microelectrophoresis measurements reveal that polylysine chains are enriched at the surface of polylysine/polyaspartic acid complex coacervates, which causes the negatively charged protein ɑ-synuclein to adsorb and accumulate at the interface. Addition of ATP inverts the surface charge, displaces ɑ-synuclein from the surface and may help to suppress its interface-catalyzed aggregation. Together, these findings show how condensate surface charge can be measured and altered, making this microelectrophoresis platform combined with automated single-particle tracking a promising characterization technique for both biomolecular condensates and coacervate protocells. The surface charge and ζ-potential of biomolecular condensates is key to their interactions with membranes and proteins. Here, the authors developed a method to determine the ζ-potential of condensates using microelectrophoresis and single-droplet tracking.