Ponceau S as a Targeted Modulator for Protein Liquid-Liquid Phase Separation

Area of Science:

• Biochemistry
• Cell Biology
• Biophysics

Background:

• Liquid-liquid phase separation (LLPS) is crucial for cellular organization and forming biomolecular condensates.
• Existing methods for inducing protein LLPS often lack precise control over time and space.

Purpose of the Study:

• To introduce Ponceau S as a novel, selective modulator for inducing and monitoring protein LLPS.
• To investigate the mechanism by which Ponceau S influences protein phase separation.
• To explore the tunability of Ponceau S-induced LLPS.

Main Methods:

• Utilized Ponceau S to induce and observe LLPS in bovine serum albumin and lysozyme.
• Analyzed Ponceau S fluorescence changes within protein-rich phases to infer molecular motion.
• Adjusted salt concentrations and 1,6-hexanediol levels to modulate droplet dynamics.

Main Results:

• Ponceau S effectively promoted protein complex formation into liquid droplets by interacting with hydrophobic regions.
• Increased Ponceau S fluorescence within droplets indicated restricted molecular motion, confirming phase separation.
• Phase separation dynamics, including droplet fusion and dissolution, were finely tunable via salt and 1,6-hexanediol concentrations.

Conclusions:

• Ponceau S acts as a selective small-molecule modulator for protein LLPS.
• Ponceau S enables precise regulation and monitoring of protein phase separation.
• This approach offers potential for advancements in biomolecular engineering, drug delivery, and synthetic biology.