Multiplectoneme phase of double-stranded DNA under torsion

Area of Science:

• Biophysics
• Molecular Biology
• Polymer Physics

Background:

• DNA supercoiling is crucial for genome organization and function.
• Existing models struggle to reconcile experimental observations of DNA behavior under tension and torque.

Purpose of the Study:

• To investigate DNA supercoiling using the wormlike chain model.
• To accurately reproduce experimental data across various conditions.
• To identify and characterize novel phases of DNA under stress.

Main Methods:

• Utilized the wormlike chain model for theoretical analysis.
• Simulated DNA behavior under varying forces, salt concentrations, and contour lengths.
• Analyzed phase transitions and critical points.

Main Results:

• The model successfully reproduced experimental data for DNA supercoiling.
• Identified a plane of first-order phase transitions.
• Discovered the multiplectoneme phase, characterized by rapid twist-mediated plectoneme diffusion and a unique torque response.

Conclusions:

• The wormlike chain model provides an accurate framework for studying DNA supercoiling.
• The newly discovered multiplectoneme phase explains previously observed discrepancies.
• This work advances our understanding of DNA mechanics and organization.