Elastic stability of DNA configurations. I. General theory

Area of Science:

• Biophysics
• Molecular Biology
• Computational Biology

Background:

• The elastic rod model is crucial for understanding DNA mechanics.
• DNA supercoiling and loop formation are fundamental to genome organization and function.
• Previous models often simplified DNA interactions and excluded volume effects.

Purpose of the Study:

• To develop and present stability criteria for DNA configurations based on the elastic rod model.
• To analyze the stability of DNA segments, including plasmids and linear DNA with end constraints.
• To investigate the impact of DNA modifications (nicking, ligation) and elastic properties on loop stability.

Main Methods:

• Application of the elastic rod model to DNA segments.
• Derivation of mathematical criteria for local energy minima, indicating stable configurations.
• Extension of explicit solution methods to include excluded volume effects and self-contact forces.
• Analysis of extranucleosomal DNA loop configurations in a DNA miniplasmid.

Main Results:

• Established criteria to assess the stability of calculated DNA equilibrium configurations.
• Demonstrated the applicability of these criteria to plasmids and anchored linear DNA.
• Quantified the influence of nicking, ligation, and elastic coefficient ratios on DNA loop stability.
• Incorporated excluded volume effects and self-contact into the elastic rod model for more realistic simulations.

Conclusions:

• The developed stability criteria provide a robust tool for analyzing DNA structural dynamics.
• Understanding DNA stability is critical for processes like replication, transcription, and packaging.
• The model's extension to include excluded volume effects enhances its predictive power for complex DNA structures.