Reversible stabilization of transition-metal-binding DNA G-quadruplexes

Area of Science:

• Biochemistry
• Supramolecular Chemistry
• Molecular Biophysics

Background:

• G-quadruplexes are four-stranded DNA structures with significant biological roles.
• Modifying G-quadruplexes can alter their stability and function.
• Terminal ligands offer sites for specific molecular interactions.

Purpose of the Study:

• To investigate the metal-triggered stabilization of tetramolecular G-quadruplexes.
• To explore the role of terminal pyridine ligands in this stabilization.
• To assess the reversibility of metal complexation.

Main Methods:

• Thermal denaturation studies to measure G-quadruplex stability.
• Circular dichroism spectroscopy to analyze structural changes.
• Nondenaturing gel electrophoresis to assess complex formation.
• Electron paramagnetic resonance (EPR) to confirm metal complex structure.

Main Results:

• Tetramolecular G-quadruplexes with terminal pyridine ligands are stabilized by copper(II) ions.
• Formation of a square-planar Cu(II)(pyridine)4 complex was confirmed.
• Stabilization was monitored effectively by thermal denaturation, CD, and gel electrophoresis.
• Metal complexation was fully reversible upon addition of ethylenediaminetetraacetic acid (EDTA).

Conclusions:

• Terminal pyridine ligands facilitate metal-triggered stabilization of tetramolecular G-quadruplexes.
• The CopperTop system demonstrates reversible control over G-quadruplex stability.
• This provides a foundation for developing dynamic G-quadruplex-based molecular systems.