Impact of Small Molecules on Intermolecular G-Quadruplex Formation

Area of Science:

• Biochemistry and Molecular Biology
• Nanotechnology and Materials Science

Background:

• Intermolecular G-quadruplex (i-GQ) structures are formed by guanine-rich DNA sequences.
• These i-GQ structures have significant physiological roles and emerging applications in biotechnology, such as DNA-based sensors and wires.
• Small molecules can influence the stability and formation of i-GQ structures, impacting their functionality.

Purpose of the Study:

• To investigate the effect of specific small molecules on intermolecular G-quadruplex formation.
• To compare the efficacy of different small molecules (L2H2-6OTD, pyridostatin, Phen-DC3) in stabilizing i-GQ structures.
• To analyze the influence of GGG repeat arrangements (3+1 GGG and 2+2 GGG) on small molecule-mediated i-GQ stabilization.

Main Methods:

• Single-molecule studies were employed to observe i-GQ formation.
• The study utilized guanine-rich DNA strands with defined GGG repeat arrangements (3+1 GGG and 2+2 GGG).
• The impact of three small molecules – L2H2-6OTD, pyridostatin (PDS), and Phen-DC3 – on i-GQ formation was assessed.

Main Results:

• Small molecules differentially enhanced i-GQ formation based on the molecule and DNA sequence arrangement.
• L2H2-6OTD significantly increased i-GQ formation by an order of magnitude in the 3+1 GGG arrangement.
• Pyridostatin and Phen-DC3 showed limited enhancement (up to three-fold) in the 2+2 GGG repeat case.

Conclusions:

• Small molecules can substantially modulate intermolecular G-quadruplex formation.
• The effectiveness of small molecules in stabilizing i-GQ structures is sequence-dependent.
• Single-molecule detection of i-GQ formation demonstrates potential for developing highly sensitive biosensors using minimal material.