G-Quadruplex Recognition by Tetraalkylammonium Ions: A New Paradigm for Discrimination between Parallel and...

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• G-quadruplexes are crucial noncanonical DNA structures regulating genomic events.
• Interconversion between G-quadruplex and duplex DNA states is key to their regulatory function.
• Developing agents to selectively target G-quadruplexes is an active area of research.

Purpose of the Study:

• To investigate the potential of tetraalkylammonium (TAA+) ions as G-quadruplex-recognizing agents.
• To determine if TAA+ ions can selectively stabilize specific G-quadruplex structures over duplex DNA.
• To explore the correlation between TAA+ ion structure and binding affinity.

Main Methods:

• Circular Dichroism (CD) spectroscopy was employed to study DNA structural changes and ion binding.
• Experiments were conducted using parallel c-MYC G-quadruplex, antiparallel human telomeric G-quadruplex, and duplex DNA.
• Varying lengths of aliphatic side chains in TAA+ ions were tested.

Main Results:

• Tetraalkylammonium ions strongly stabilize the parallel c-MYC G-quadruplex.
• TAA+ ions showed no binding to antiparallel human telomeric G-quadruplex or duplex DNA.
• Binding affinity correlated with the length of the aliphatic side chains of the TAA+ ions.
• CD spectral data indicated external binding without altering the G-quadruplex structure.

Conclusions:

• Tetraalkylammonium ions exhibit remarkable topology selectivity for G-quadruplex DNA.
• These ions can discriminate between different G-quadruplex structures and duplex DNA.
• TAA+ salts serve as a promising starting point for the development of topology-selective G-quadruplex-binding agents.