Damage sensor role of UV-DDB during base excision repair

Area of Science:

• Molecular Biology
• DNA Repair Mechanisms
• Biochemistry

Background:

• UV-damaged DNA binding (UV-DDB) protein is crucial for nucleotide excision repair (NER).
• UV-DDB binds abasic sites and 8-oxo-guanine (8-oxoG), suggesting roles beyond NER.
• 8-oxoG and abasic sites are common DNA lesions repaired by base excision repair (BER).

Purpose of the Study:

• To investigate if UV-DDB stimulates BER for 8-oxoG and abasic sites.
• To elucidate the mechanism by which UV-DDB might enhance BER.
• To determine the in vivo role of UV-DDB in response to oxidative DNA damage.

Main Methods:

• In vitro assays measuring strand cleavage by 8-oxoguanine glycosylase (OGG1) and apurinic/apyrimidinic endonuclease (APE1) in the presence of UV-DDB.
• Single-molecule real-time imaging to observe protein-DNA interactions.
• Cellular studies tracking UV-DDB localization and assessing sensitivity to oxidative damage upon UV-DDB depletion.

Main Results:

• UV-DDB significantly increased OGG1 and APE1 strand cleavage activity.
• UV-DDB enhanced DNA polymerase β-mediated gap filling by 30-fold.
• Single-molecule imaging showed UV-DDB facilitates OGG1/APE1 dissociation from DNA.
• UV-DDB localizes to 8-oxoG repair sites in cells, and its depletion increases sensitivity to oxidative DNA damage.

Conclusions:

• UV-DDB plays a role in stimulating BER for oxidative DNA damage.
• UV-DDB acts as a general DNA damage sensor, facilitating repair in both NER and BER pathways.
• UV-DDB enhances DNA damage recognition and repair efficiency within the chromatin context.