Supercoils Stabilize a "DNA Corset" Condensate with Torsion-Dependent Hysteretic Compaction

Area of Science:

• Cell Biology
• Biophysics
• Molecular Biology

Background:

• Biomolecular condensates are essential for cellular organization.
• Regulating condensate size is crucial for controlling biochemical reactions.
• The microscopic mechanisms for condensate size regulation are not well understood.

Purpose of the Study:

• To investigate the role of DNA supercoiling in regulating biomolecular condensate size and structure.
• To visualize the physical mechanisms of DNA-protein condensate formation and dynamics.

Main Methods:

• Developed a coarse-grained DNA-protein model incorporating DNA torsional flexibility.
• Simulated DNA-protein interactions and phase separation dynamics.
• Visualized the effects of DNA supercoiling on condensate morphology.

Main Results:

• DNA supercoiling induces a compact "DNA corset" structure in condensates.
• Increased supercoiling compacts the condensate, while relaxation expands it.
• DNA length influences the reversibility and hysteresis of supercoiling-induced transitions.

Conclusions:

• DNA supercoiling acts as a topological switch controlling condensate mechanics.
• This mechanism links DNA topology to the dynamic regulation of chromatin condensates.
• Provides a physical framework for designing topology-based condensates.