UvrA

uvrA is a bacterial gene that encodes the UV repair A (UvrA) protein, a central component of the nucleotide excision repair (NER) pathway. In many bacteria, including Escherichia coli, UvrA participates in the initial recognition of DNA damage and works together with UvrB to locate lesions caused by ultraviolet light and other DNA-damaging agents.

UvrA functions as a damage sensor that forms a complex with UvrB. The predominant functional form is a UvrA2-UvrB complex, which scans the genome for distortions in the DNA helix. UvrA contains two ATPase domains and two ATP-binding sites; ATP binding and hydrolysis drive conformational changes that promote stable interaction with damaged DNA and the recruitment of UvrB. Once a lesion is detected, UvrB is positioned at the damage and UvrA dissociates to allow UvrC to make incisions on both sides of the damaged strand. The damaged oligonucleotide is then removed by a helicase/exonuclease activity, and DNA polymerase fills the gap followed by ligation.

Expression of uvrA is part of the bacterial SOS response, induced by DNA damage. The LexA repressor normally suppresses SOS genes, and RecA-mediated cleavage of LexA increases transcription of uvrA, along with other repair genes such as uvrB, uvrC, and uvrD.

Genetically, uvrA is often co-located with uvrB and uvrC in operons or gene clusters involved in excision repair. The UvrA protein is typically around 90–95 kDa, comprising multiple DNA-binding domains and the two ATPase modules that underpin its activity in damage recognition.