Structures and Dynamics of DNA Mini-Dumbbells Are Force Field Dependent

Area of Science:

• Biophysics
• Computational Biology
• Structural Biology

Background:

• Flexible nucleic acid structures are difficult to resolve experimentally.
• Molecular dynamics (MD) simulations offer an alternative for studying biomolecule dynamics.
• Accurate modeling of noncanonical nucleic acids using MD has been challenging.

Purpose of the Study:

• Evaluate current nucleic acid force fields for modeling flexible DNA structures.
• Assess the ability of MD simulations to capture DNA mini-dumbbell dynamics.
• Compare simulation results with experimental nuclear magnetic resonance (NMR) data.

Main Methods:

• Re-refinement of DNA mini-dumbbell structures using NMR data in explicit solvent.
• Collection of over 800 microseconds of MD simulation data for two DNA sequences across eight force fields.
• Evaluation of Amber (bsc0, bsc1, OL15, OL21), Charmm (Charmm36, Drude), and independent (Tumuc1, CuFix/NBFix) force fields.

Main Results:

• Recently developed nucleic acid force fields show good agreement with experimental NMR data for DNA mini-dumbbell structures.
• Slight variations in structural modeling were observed between different force fields and DNA sequences.
• Each tested force field produced a unique distribution of potentially anomalous structures.

Conclusions:

• Improved nucleic acid force fields enhance the accuracy of MD simulations for flexible DNA.
• MD simulations, coupled with advanced force fields, are valuable tools for understanding DNA dynamics.
• Further investigation is needed to address the force field-dependent variations in anomalous structure populations.