Probing the surface charge of condensates using microelectrophoresis

Area of Science:

• Cellular Biology
• Biophysics
• Biochemistry

Background:

• Biomolecular condensates are crucial for cellular organization.
• Coacervates serve as models for these condensates.
• Condensate surface properties, like charge, are vital but poorly understood.

Purpose of the Study:

• To develop a method for accurately measuring coacervate surface charge and zeta potential.
• To investigate the influence of surface charge on protein adsorption and aggregation.
• To explore methods for altering condensate surface properties.

Main Methods:

• Microelectrophoresis and single-particle tracking were employed.
• This approach overcomes limitations of laser Doppler electrophoresis for fluid condensates.
• Electrophoretic mobility and zeta potential were calculated for coacervates.

Main Results:

• Coacervates exhibit size-dependent electrophoretic mobility due to their fluid nature.
• Polylysine enrichment at the coacervate surface drives alpha-synuclein adsorption.
• ATP addition reverses surface charge and displaces alpha-synuclein, potentially inhibiting aggregation.

Conclusions:

• A novel microelectrophoresis platform accurately characterizes coacervate surface charge.
• Surface charge modulation can control protein interactions at condensate interfaces.
• This technique is valuable for studying biomolecular condensates and protocells.