UvrABC

UvrABC endonuclease is a prokaryotic DNA repair complex that mediates nucleotide excision repair (NER) in bacteria. It comprises three proteins—UvrA, UvrB, and UvrC—encoded by the uvrA, uvrB, and uvrC genes. The complex recognizes a broad range of bulky DNA lesions, including UV-induced pyrimidine dimers and other helix-distorting damages, and initiates their removal to restore DNA integrity.

In the classical global genome repair pathway, UvrA and UvrB form a scanning complex (often as UvrA2B2) that patrols the genome for distortions. Upon lesion detection, UvrB verifies the damage and UvrA dissociates, allowing UvrC to bind. UvrC then introduces incisions on the damaged strand on both sides of the lesion, producing a short single-stranded segment containing the damage. The excised fragment is removed with the assistance of UvrD helicase, and the resulting gap is filled by DNA polymerase I. Finally, DNA ligase seals the remaining nick, completing the repair.

UvrABC activity is essential for survival after UV exposure and protection against a broad spectrum of bulky DNA lesions that distort the DNA helix. Deficiency in any of the components (UvrA, UvrB, or UvrC) leads to marked UV sensitivity and accumulation of DNA damage. The UvrABC system is a well-studied model for bacterial nucleotide excision repair and reflects the core strategies by which bacteria maintain genome integrity in the face of environmental DNA damage.