Modulation of Hoogsteen dynamics on DNA recognition

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• DNA exists in a dynamic equilibrium between Watson-Crick and Hoogsteen base pairing configurations.
• Understanding these dynamics is crucial for comprehending DNA-ligand and DNA-protein interactions.

Purpose of the Study:

• To investigate how DNA recognition by small molecules affects Watson-Crick/Hoogsteen base pair dynamics.
• To elucidate the role of Hoogsteen dynamics in DNA-drug interactions.

Main Methods:

• Utilized nuclear magnetic resonance (NMR) relaxation dispersion spectroscopy.
• Employed molecular dynamics (MD) simulations.
• Analyzed the effects of echinomycin and actinomycin D on DNA base pair dynamics.

Main Results:

• DNA recognition by echinomycin and actinomycin D quenched Hoogsteen dynamics at specific base pairs involved in hydrogen bonding.
• Echinomycin binding led to a 10-fold increase in Hoogsteen population at flanking base pairs, likely due to stacking interactions.
• Actinomycin D showed minimal impact on Hoogsteen dynamics at non-binding sites.

Conclusions:

• Modulation of Hoogsteen dynamics is a key feature of DNA recognition by ligands.
• These findings suggest a general mechanism for how DNA-ligand and DNA-protein interactions occur.
• Altered base pair dynamics may play a significant role in molecular recognition events at the DNA interface.