Chemically accurate coarse graining of double-stranded DNA

Area of Science:

• Computational Biology
• Biophysics
• Molecular Dynamics

Background:

• Coarse-grained (CG) models are essential for simulating DNA's role in chromatin folding and genomic packaging.
• Accurate simulation of local DNA chain motions is critical for predicting DNA persistence length, especially with changing ionic strength.
• Existing CG models lack sufficient fidelity in capturing these local motions.

Purpose of the Study:

• To develop an accurate coarse-grained (CG) model for double-stranded DNA.
• To explicitly incorporate mobile ions into the CG model.
• To ensure the model accurately reproduces DNA local dynamics and persistence length across various ionic strengths.

Main Methods:

• Systematic derivation of the CG model from all-atom molecular dynamics simulations.
• Explicit treatment of mobile ions within the simulation framework.
• Validation against experimental data for DNA persistence length dependence on ionic strength.

Main Results:

• The developed CG model captures complex local DNA chain motions comparable to all-atom simulations.
• Simulation results show quantitative agreement with experimental data on DNA persistence length versus ionic strength.
• A predicted structural transition in DNA nanocircles at elevated ionic strengths was observed.

Conclusions:

• The new CG DNA model offers improved accuracy for simulating biological processes like chromatin folding.
• The model's fidelity in representing local motions and ionic strength effects is a significant advancement.
• This model provides a valuable tool for studying DNA behavior in diverse solution conditions.