An electron paramagnetic resonance probe to detect local Z-DNA conformations

Area of Science:

• Molecular Biology
• Biophysics
• Spectroscopy

Background:

• DNA exists in various conformations, including the B-DNA and Z-DNA forms.
• Detecting local DNA conformations is crucial for understanding DNA function and regulation.
• Electron Paramagnetic Resonance (EPR) spectroscopy is a sensitive technique for probing molecular dynamics.

Purpose of the Study:

• To develop and validate an Electron Paramagnetic Resonance (EPR) probe for detecting local Z-DNA conformations.
• To investigate the local base dynamics within Z-DNA structures.

Main Methods:

• Synthesis of a spin-labeled alternating co-polymer, (dG-dC,DCAT)n, using deoxycytidine-5'-triphosphate (pppDCAT) and Micrococcus luteus DNA polymerase.
• Analysis of EPR spectra of the synthesized DNA in Z-DNA conformation.
• Comparison of EPR spectra with computed values for B-DNA.
• Control experiments using (dA-dT, DUAT)n to rule out salt-induced artifacts.

Main Results:

• Spectroscopic evidence for the detection of local Z-DNA conformations using an EPR probe.
• The EPR spectrum of (dG-dC,DCAT)n in Z-DNA conformation showed a twofold decrease in local base dynamics compared to B-DNA.
• Control experiments confirmed that observed effects were not due to salt-induced artifacts.

Conclusions:

• The developed EPR probe is effective in detecting local Z-DNA conformations.
• Z-DNA exhibits significantly reduced local base dynamics compared to B-DNA.
• This EPR-based approach provides a valuable tool for studying DNA structural dynamics.