UvrBDNA

UvrBDNA refers to the intermediate formed when the UvrB protein binds to DNA during bacterial nucleotide excision repair. In many bacteria, including Escherichia coli, UvrB cooperates with UvrA to scan the genome for helix-distorting lesions. When damage is detected, UvrA dissociates and UvrB remains bound at the site, creating a UvrB-DNA complex that helps verify the lesion and recruits the incision nuclease UvrC.

Within the UvrB-DNA complex, UvrB uses ATP hydrolysis to drive conformational changes in its helicase-like core and to regulate its interaction with DNA. A conserved DNA-binding pocket and a beta-hairpin structure insert into the duplex, stabilizing the bend and exposing the damaged strand for incision. The complex is typically transient, acting as a checkpoint that ensures damage recognition before the dual incisions proceed.

Following the formation of the UvrBC complex, UvrC performs incisions on the damaged strand at sites flanking the lesion, typically on the 5' and 3' sides. The resulting oligonucleotide fragment containing the lesion is removed, with the UvrD helicase unwinding the DNA to excise the damaged segment. DNA polymerase I then fills the resulting gap and DNA ligase seals the strand, completing the repair.

Mutations that impair UvrB function or its interaction with DNA can lead to increased sensitivity to ultraviolet radiation and a higher mutation rate. Structural and biochemical studies of the UvrB-DNA interface have illuminated how ATP binding and hydrolysis, as well as DNA distortions, govern damage verification and progression of the repair pathway.