APE1 incision activity at abasic sites in tandem repeat sequences

Area of Science:

• Genomics
• Molecular Biology
• DNA Repair

Background:

• Repetitive DNA sequences comprise ~30% of the human genome.
• These regions are prone to oxidative damage and genome instability.
• Understanding DNA repair in repetitive sequences is vital for genomic integrity.

Purpose of the Study:

• To investigate human apurinic/apyrimidinic endonuclease 1 (APE1) activity at AP sites within repetitive DNA.
• To determine how sequence, conformation, and lesion positioning affect APE1 function in telomeric and CAG/CTG repeats.

Main Methods:

• Utilized designed oligonucleotide substrates containing repetitive DNA sequences.
• Assessed APE1 binding and strand incision at apurinic/apyrimidinic (AP) sites.
• Analyzed the influence of DNA substrate properties on APE1 endonuclease activity.

Main Results:

• APE1 cleavage efficiency is differentially influenced by repetitive DNA sequence, conformation, and AP site location.
• A significant correlation was observed between APE1 endonuclease efficiency and DNA substrate thermodynamic stability.
• These findings highlight the impact of DNA structure on repair protein function.

Conclusions:

• APE1's repair activity is modulated by the unique characteristics of repetitive DNA domains.
• DNA thermodynamic stability is a key factor influencing APE1 efficiency in these regions.
• Results provide mechanistic insights into DNA repair in oxidatively sensitive, conformationally dynamic repetitive sequences.