On the truncation of long-range electrostatic interactions in DNA

Area of Science:

• Computational chemistry
• Biophysics
• Molecular modeling

Background:

• Long-range interactions are critical for accurate molecular dynamics simulations of polar biomolecules like DNA.
• Stable nanosecond trajectories for nucleic acids and proteins depend on precise handling of these interactions.

Purpose of the Study:

• To evaluate the structural and dynamic impacts of various long-range electrostatic truncation methods on a charged oligonucleotide in aqueous solution.
• To identify optimal methods for stable and accurate molecular dynamics simulations of nucleic acids.

Main Methods:

• Comparison of group-based truncation methods (switching function, force-switching, abrupt truncation) and particle mesh Ewald (PME).
• Evaluation of atom-based truncation methods with varying cutoff radii and force-shifting functions.
• Analysis of root mean square (rms) deviations and fluctuations to assess trajectory stability and structural integrity.

Main Results:

• Group-based methods with switching functions and short cutoffs resulted in unstable trajectories and significant structural distortions.
• Abrupt truncation at longer cutoffs (12.0 Å) and particle mesh Ewald (PME) yielded stable trajectories.
• Atom-based truncation methods also produced stable trajectories, comparable to PME, with rms deviations of 1.5-1.7 Å.
• Computational cost increased with cutoff radius for atom-based methods, while PME was more computationally intensive for direct space calculations.

Conclusions:

• Atom-based force-shift and PME methods are recommended for accurate and stable long-range electrostatic treatment in molecular dynamics of charged biomolecules.
• The B-DNA form is maintained regardless of the truncation method, suggesting dependence on energy function parameters.
• Terminal nucleotides, particularly cytidines, exhibit higher flexibility compared to internal ones.