Coarse-Grained Simulation of Rodlike Higher-Order Quadruplex Structures at Different Salt Concentrations.

Area of Science:

• Biophysics
• Computational Biology
• Molecular Modeling

Background:

• Higher-order quadruplexes are complex DNA/RNA structures with significant biological roles.
• Previous coarse-grained (CG) models were limited to minimal salt conditions.
• Understanding quadruplex behavior at variable ionic strengths is crucial for biological applications.

Purpose of the Study:

• To develop and validate an improved CG model for rodlike higher-order quadruplexes.
• To investigate the effects of salt concentration and stacking on quadruplex elasticity.
• To extend the applicability of CG models to physiological salt conditions.

Main Methods:

• Developed a CG model using inverse Monte Carlo from atomistic simulations.
• Incorporated explicit monovalent salts to account for ionic strength.
• Analyzed quadruplex elasticity and structural parameters (rise, twist) via simulations.

Main Results:

• The CG model accurately reproduces experimental observations of terminal deformations.
• Elasticity and structural parameters show dependence on salt concentration and quadruplex stacking.
• The model functions effectively across a range of ionic strengths.

Conclusions:

• The improved CG model provides a reliable tool for studying quadruplexes under various salt conditions.
• Findings offer insights into the mechanical properties of G-quartet-based biopolymers.
• The model's generalizability aids in understanding diverse G-quadruplex structures.