Atomistic model of DNA: phonons and base-pair opening

Area of Science:

• Molecular Biophysics
• Computational Biology
• Structural Biology

Background:

• Understanding DNA's mechanical properties is crucial for molecular biology.
• Previous models have limitations in capturing low-frequency vibrational dynamics.

Purpose of the Study:

• To develop and validate a fully atomistic model of B-DNA.
• To investigate the low-frequency vibrational modes of DNA and their relation to base-pair opening.

Main Methods:

• Utilizing the CHARMM (Chemistry at Harvard Molecular Mechanics) force field for an atomistic B-DNA model.
• Employing molecular dynamics simulations to achieve an equilibrium structure.
• Performing large-scale phonon calculations using interatomic force constants from CHARMM.

Main Results:

• The atomistic B-DNA model demonstrates high accuracy in low-frequency vibrational modes compared to experimental data.
• Identified widely reported modes below 12.5 meV.
• Discovered a continuous band of modes with significant base-pair opening character extending up to 40 meV.

Conclusions:

• The CHARMM-based atomistic model accurately captures DNA's low-frequency vibrational dynamics.
• These vibrational modes, particularly those up to 40 meV, are strongly associated with base-pair opening.
• The findings provide insights into DNA denaturation mechanisms at a molecular level.