How a Single 5 eV Electron Can Induce Double-Strand Breaks in DNA: A Time-Dependent Density Functional Theory Study.

Area of Science:

• Biophysics
• Chemical Physics
• Molecular Biology

Background:

• Low-energy electrons (<20 eV) induce DNA damage via transient anions (TAs).
• Shape resonances cause single-strand breaks (SSBs), while core-excited resonances can cause cluster lesions.
• Understanding electron-DNA interactions is crucial for radiation biology and nanomedicine.

Purpose of the Study:

• To investigate the mechanism by which core-excited resonances induce double-strand breaks (DSBs) in DNA.
• To model electron-induced DNA damage using computational methods.
• To determine the specific electron energy required for DSB induction via core-excited resonances.

Main Methods:

• Time-dependent density functional theory (TDDFT) was employed.
• Potential energy surfaces (PESs) of excited states of DNA transient anions were calculated.
• The model system used was a DNA nucleotide with a G-C base pair (ds[5'-G-3']).

Main Results:

• Shape resonances occur at ~1 eV, inducing SSBs.
• Core-excited resonances occur above 4 eV, with a dissociative state identified at 5.4 eV.
• A single 5 eV electron can induce a DSB by transferring charge within the phosphate group, creating two lesions.

Conclusions:

• Core-excited resonances are capable of inducing double-strand breaks (DSBs) in DNA.
• A single low-energy electron (~5 eV) can cause significant DNA damage, forming clustered lesions.
• These findings advance our understanding of DNA damage mechanisms at the molecular level.