A coarse-grain three-site-per-nucleotide model for DNA with explicit ions

Area of Science:

• Computational biology
• Biophysics
• Molecular modeling

Background:

• The three sites per nucleotide (3SPN) model is a coarse-grained approach for simulating nucleic acids.
• Previous versions used implicit ions based on Debye-Hückel theory, limiting accuracy.
• Accurate modeling of ionic environments is crucial for understanding DNA behavior.

Purpose of the Study:

• To develop an improved coarse-grained model for nucleic acids with explicit ions.
• To represent both monovalent and divalent ions in the simulation environment.
• To validate the model against atomistic simulations and experimental data.

Main Methods:

• Developed coarse-grain ion-ion and ion-phosphate potentials from all-atom simulations.
• Parameterized the model to capture local ion structure and organization near DNA.
• Introduced the 3SPN.1-I model incorporating explicit ions.

Main Results:

• The 3SPN.1-I model successfully reproduces local ion structures seen in atomistic simulations.
• The model accurately predicts experimental DNA melting temperatures.
• Performance was validated across varying DNA lengths, CG-content, and ion concentrations (Na+, Mg2+).

Conclusions:

• The 3SPN.1-I model offers a significant advancement in coarse-grained nucleic acid simulations.
• Explicit ion representation enhances the predictive power for DNA physical properties.
• This model facilitates more accurate simulations of DNA in diverse ionic conditions.