New insights into the structures of ligand-quadruplex complexes from molecular dynamics simulations

Area of Science:

• Biochemistry
• Structural Biology
• Computational Chemistry

Background:

• G-quadruplexes are higher-order DNA/RNA structures formed from guanine-rich sequences.
• These structures are attractive targets for anticancer drug development.
• Understanding ligand-G-quadruplex interactions is crucial for drug lead discovery.

Purpose of the Study:

• To investigate the three-dimensional interactions between G-quadruplex structures and six different ligands using molecular dynamics simulations.
• To elucidate the binding mechanisms and stability effects of ligand-G-quadruplex complexes in aqueous solution.

Main Methods:

• Molecular dynamics simulations were performed on six G-quadruplex-ligand complexes.
• Computational analyses were used to study ion movement, hydrogen bonding, and binding site interactions.
• Structures were based on crystallographic or NMR data.

Main Results:

• Ligand binding causes ions to move away from the G-quartet, facilitating binding in aqueous solution.
• Ligand interactions can enhance the stability of Hoogsteen hydrogen bonds within the G-quartet.
• The G-quadruplex binding site accommodates only one ligand molecule, and loop/flank interactions may not always stabilize the complex.

Conclusions:

• Ligand binding to G-quadruplexes involves ion displacement and stabilization of internal hydrogen bonds.
• The binding site's limited capacity and variable interaction stability are key considerations.
• Findings can guide the design of more selective and potent G-quadruplex-targeting anticancer drugs.