DNA double strand cleavage via interstrand hydrogen atom abstraction

Area of Science:

• Biochemistry
• DNA Damage and Repair
• Medicinal Chemistry

Background:

• Double-strand breaks (DSBs) represent the most severe form of DNA damage.
• Natural products inducing DSBs are potent cytotoxic agents.
• Developing agents that cause DSBs through a single chemical event is a significant challenge.

Purpose of the Study:

• To elucidate the mechanism by which a C4 -nucleotide radical leads to DSBs in duplex DNA.
• To identify key chemical events in DSB formation.
• To provide a basis for designing novel DNA damaging agents.

Main Methods:

• Investigated DNA radical formation under aerobic conditions.
• Analyzed the chemical pathway from initial radical to DSB.
• Utilized mechanistic studies to understand hydrogen atom abstraction in DNA cleavage.

Main Results:

• Formation of a C4 -nucleotide radical in duplex DNA under aerobic conditions directly results in a DSB.
• The initial radical generates a strand break with a peroxyl radical.
• This peroxyl radical abstracts a hydrogen atom from the opposite strand, causing cleavage.

Conclusions:

• A novel mechanism for DSB formation initiated by a C4 -nucleotide radical has been identified.
• This mechanism involves sequential radical reactions and hydrogen atom abstraction.
• The findings provide a rationale for designing targeted DNA damaging agents that exploit this pathway.