Molecular mechanisms behind BRACO19 and human telomeric G-quadruplex interaction

Area of Science:

• Biochemistry
• Molecular Biology
• Drug Discovery

Background:

• Human telomeres (HTs) form G-quadruplex (G4) structures, which are promising targets for anticancer and antiviral therapies.
• The structural polymorphism of HT-G4s complicates the specific recognition by ligands, hindering drug development.

Purpose of the Study:

• To investigate how different topologies of a human telomere segment (Tel22) affect its interaction with the G4 ligand BRACO19.
• To understand the role of cations in modulating HT-G4 structure and ligand binding.

Main Methods:

• Utilized contactless spectroscopic techniques including Circular Dichroism (CD) and UV resonance Raman (UVRR) spectroscopy.
• Employed UV-visible absorption and steady-state fluorescence spectroscopy to analyze electronic features and photoresponsive properties.
• Investigated the impact of potassium (K+) and sodium (Na+) ions on Tel22 G4 structure and BRACO19 binding.

Main Results:

• Cation-induced modifications in Tel22 topology critically determine ligand interactions and binding modes with BRACO19.
• Fluorescence spectroscopy effectively detects cation-driven multimeric structures of HT-G4s.
• Altered HT-G4 assembly capabilities were observed based on cation presence.

Conclusions:

• Cation-dependent structural variations in HT-G4s significantly influence their interaction with ligands like BRACO19.
• Fluorescence offers a valuable method for identifying potentially pathological multimeric G4 structures in biological systems.
• Understanding these cation-mediated interactions is crucial for developing targeted G4-based therapies.