Toroidal structures due to anisotropy of DNA-like molecules

Area of Science:

• Biophysics
• Materials Science

Background:

• DNA molecules exhibit complex conformations influenced by elasticity and charge neutralization.
• Mesoscale anisotropy plays a role in the organization of DNA structures.

Purpose of the Study:

• To investigate the formation of toroidal structures in DNA psi-condensation.
• To model the influence of anisotropy and molecular properties on DNA conformation.

Main Methods:

• Modeling a B-DNA molecule as an anisotropic elastic rod subjected to torque.
• Numerical simulation of the DNA model under varying conditions.
• Analysis of structural changes (toroidal to spherical) based on elastic moduli and counterion layer properties.

Main Results:

• Toroidal structures of a few persistence lengths form under specific conditions, aligning with experimental data.
• Simulations demonstrate that changes in elastic moduli or counterion layer characteristics can transform toroidal structures into spherical ones.
• Mesoscale anisotropy is identified as a potential cause for toroidal structures in DNA psi-condensation.

Conclusions:

• Anisotropic properties on the mesoscale are crucial for the formation of toroidal DNA structures.
• The elasticity and counterion layer of DNA molecules significantly influence their conformational states.
• Further investigation into Z-DNA's psi-condensation could elucidate the role of anisotropy.