Mechanistic insight into ligand binding to G-quadruplex DNA

Area of Science:

• Genomics and molecular biology
• Medicinal chemistry
• Computational biophysics

Background:

• Guanine-rich sequences in the human genome form G-quadruplex structures, influencing biological processes like apoptosis.
• Telomeric G-quadruplexes are targets for antitumor therapy, with small molecules stabilizing them offering therapeutic potential.
• Compound 1, a novel ligand, exhibits in vitro antitumor activity by interacting with the [d(TGGGGT)]4 G-quadruplex, but its binding mechanism is complex.

Purpose of the Study:

• To elucidate the detailed binding mechanism of Compound 1 to the [d(TGGGGT)]4 G-quadruplex using computational simulations.
• To understand the free-energy landscape governing the ligand-DNA interaction.
• To provide a comprehensive explanation for Compound 1's observed experimental activity.

Main Methods:

• Metadynamics simulations were employed to investigate the binding process.
• The ligand's exploration of all potential binding sites on the G-quadruplex was analyzed.
• The free-energy landscape of the binding event was computed.

Main Results:

• A novel "hopping" binding mechanism was discovered, where Compound 1 binds to both the groove and the 3' end of the G-quadruplex.
• The simulations mapped the ligand's interactions and conformational changes during binding.
• The computed free-energy landscape provided insights into the stability of different binding modes.

Conclusions:

• The study provides a comprehensive understanding of Compound 1's complex binding mechanism to telomeric G-quadruplexes.
• The findings fully rationalize existing experimental data on Compound 1's activity.
• The computational approach is valuable for future development of ligand-DNA therapeutics.