Hydrodynamic Models of G-Quadruplex Structures.

Area of Science:

• Structural Biology
• Biophysics
• Computational Biology

Background:

• G-quadruplexes are noncanonical four-stranded DNA/RNA structures formed by guanine-rich sequences.
• G-quadruplexes exhibit diverse topologies due to tetrad stacking and loop variations.
• High-resolution structures of short G-quadruplexes are known, but higher-order structures in longer sequences remain challenging to characterize.

Purpose of the Study:

• To develop and describe an integrated computational and experimental approach for modeling higher-order G-quadruplex structures.
• To obtain structural models for G-quadruplexes potentially forming in longer telomeric or promoter sequences.
• To validate these models using experimentally testable hydrodynamic properties.

Main Methods:

• Atomic-level model building based on folding principles from known high-resolution structures.
• Molecular dynamics optimization of atomic-level models.
• Construction of bead models using HYDROPRO to predict hydrodynamic properties.
• Validation of models by comparing predicted hydrodynamic properties with experimental measurements (e.g., analytical ultracentrifugation).

Main Results:

• An integrated approach combining computational modeling and experimental validation was successfully implemented.
• Structural models for higher-order G-quadruplexes were generated.
• Predicted hydrodynamic properties from the models showed good agreement with experimental data.

Conclusions:

• The described integrated approach provides a viable strategy for characterizing higher-order G-quadruplex structures in longer nucleic acid sequences.
• This method enables the prediction and validation of G-quadruplex structures using biophysical properties.
• The approach facilitates a deeper understanding of G-quadruplex formation in biologically relevant contexts like telomeres and promoters.