Solution structure of a G-quadruplex bound to the bisquinolinium compound Phen-DC(3)

Area of Science:

• Biochemistry
• Structural Biology
• Medicinal Chemistry

Background:

• G-quadruplexes are unique nucleic acid structures implicated in various biological processes, including cancer.
• Phen-DC3 is a compound demonstrating significant biological activity through interaction with G-quadruplexes.

Purpose of the Study:

• To elucidate the structural basis of Phen-DC3's interaction with a specific G-quadruplex.
• To guide the rational design of modified Phen-DC3 analogs for enhanced G-quadruplex targeting.

Main Methods:

• Nuclear Magnetic Resonance (NMR) spectroscopy was employed to determine the three-dimensional structure of the Phen-DC3-G-quadruplex complex.
• The G-quadruplex was derived from the c-myc promoter region, a known biologically relevant target.

Main Results:

• The high-resolution structure revealed that Phen-DC3 binds to the G-quadruplex via extensive π-stacking interactions with the guanine bases of the top G-tetrad.
• Detailed structural insights into the binding interface were obtained.

Conclusions:

• The determined structure provides a molecular understanding of Phen-DC3's binding to G-quadruplexes.
• Proposed structural modifications can lead to the development of more selective and potent G-quadruplex-targeting agents for therapeutic applications.