uvrC

uvrC is a gene encoding the UvrC protein, a component of the bacterial nucleotide excision repair (NER) pathway. UvrC works as part of the UvrABC endonuclease complex that recognizes a wide range of DNA lesions, including ultraviolet (UV)–induced pyrimidine dimers. In many bacteria, including Escherichia coli, UvrC collaborates with UvrA and UvrB to locate damaged DNA and to excise the lesion-containing segment.

UvrC introduces incisions on both sides of the damaged site, enabling removal of the lesion-containing DNA fragment. The N-terminal GIY-YIG nuclease domain carries out the 3′ incision, while a C-terminal nuclease domain carries out the 5′ incision. The resulting fragment is typically about 12–13 nucleotides long and is released, with UvrD helicase helping to displace the fragment. DNA polymerase I fills the resulting gap and DNA ligase seals the final nick to restore an intact strand.

Structure and domains of UvrC typically include an N-terminal GIY-YIG nuclease domain, a central region that facilitates interaction with UvrB, and a C-terminal nuclease domain containing a helix-hairpin-helix (HhH) motif. The protein is roughly 610 amino acids in Escherichia coli, and its multi-domain architecture supports coordinated damage recognition, incision, and repair.

Genetic and biological significance: uvrC is part of the bacterial SOS response, with expression induced by DNA damage through the LexA repressor. Loss of uvrC leads to increased sensitivity to UV light and other DNA-damaging agents, reflecting its essential role in maintaining genomic integrity. The gene is widespread among bacteria, though some species rely on alternative repair pathways or lack UvrC altogether.