Porphyrin Binding and Irradiation Promote G-Quadruplex DNA Dimeric Structure

Area of Science:

• Biochemistry
• Molecular Biology
• Nanotechnology

Background:

• Nucleic acid sequences rich in guanines form noncanonical DNA G-quadruplexes (G4s).
• Small molecules stabilizing G4s are explored for anticancer therapies and nanotechnologies.
• Porphyrins are attractive G4 binders due to their light-activation properties.

Purpose of the Study:

• To investigate the interaction between TMPyP4 porphyrin and a human telomeric sequence (Tel22).
• To study the effect of blue light irradiation on the Tel22-TMPyP4 complex.
• To establish a link between dimerization and conformational changes in G4s.

Main Methods:

• Structure-based strategy using complementary probes.
• Studying the Tel22-TMPyP4 complex before and after blue light irradiation.
• Analyzing secondary and quaternary structural modifications.

Main Results:

• Porphyrin binding promotes Tel22 dimerization.
• Light irradiation of the Tel22-TMPyP4 complex controls the dimer fraction.
• Quaternary structure changes are correlated with secondary structure modifications.

Conclusions:

• Porphyrin-DNA interactions can be modulated by light.
• A link exists between G4 dimerization and conformational changes.
• This study offers insights into G4 conformational regulation for therapeutic and nanotechnological applications.