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Updated: May 25, 2026
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Stable DNA Motifs, 1D and 2D Nanostructures Constructed from Small Circular DNA Molecules
Published on: April 12, 2019
Molecular dynamics of a DNA Holliday junction: the inverted repeat sequence d(CCGGTACCGG)₄
Elizabeth G Wheatley1, Susan N Pieniazek, Ishita Mukerji
1Department of Chemistry, Wesleyan University, Middletown, Connecticut, USA.
Biophysical Journal
|February 14, 2012
Summary
Molecular dynamics simulations validate the accuracy of modeling unusual DNA structures like the four-way junction (4WJ). Simulations show the stacked-X form is stable and provide insights into DNA junction conformational changes.
Area of Science:
- Structural Biology
- Computational Biology
- Biophysics
Background:
- All-atom molecular dynamics (MD) simulations are established for duplex DNA but require validation for unusual structures.
- The four-way junction (4WJ), or Holliday junction, is a critical DNA structure in cellular processes like replication and repair.
- Two main 4WJ conformations exist: planar open-X (OPN) and stacked-X (STX), with STX stabilized by high salt.
Purpose of the Study:
- To assess the accuracy of MD force fields for modeling the dynamic behavior of 4WJs.
- To investigate the conformational stability and dynamics of the d(CCGGTACCGG)(4) sequence in its STX and OPN forms.
- To provide insights into the conformational transition between OPN and STX forms and counterion distribution.
Main Methods:
- Performed explicit solvent all-atom molecular dynamics (MD) simulations of approximately 100 ns.
- Simulated the repeat sequence d(CCGGTACCGG)(4) starting from both crystal (STX) and built (OPN) structures.
- Analyzed simulation trajectories to determine structural convergence and conformational stability.
Main Results:
- All MD simulations converged to a stable stacked-X (STX) structure, consistent with experimental crystal structures.
- Simulations initiated from the open-X (OPN) form spontaneously transitioned to the STX form under both high and low salt conditions.
- The study provides a validated dynamical model for the STX form and new data on junction stability and counterion behavior.
Conclusions:
- MD simulations accurately capture the dynamics of the STX four-way DNA junction.
- The OPN to STX conformational transition is spontaneous, offering a model for this dynamic process.
- These findings validate MD approaches for unusual DNA structures and enhance understanding of 4WJ stability and ion interactions.
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