UvrD

uvrD is a bacterial gene that encodes a DNA helicase known as UvrD, or DNA helicase II. It belongs to the helicase superfamily 1 and translocates along DNA in the 3' to 5' direction, using energy from ATP hydrolysis. The protein is typically cytosolic and is widely conserved across bacterial species. In Escherichia coli, UvrD is commonly referred to as helicase II.

In nucleotide excision repair, UvrD acts after the UvrA–UvrB damage recognition step. Following incision of the damaged strand by UvrC, UvrD binds near the lesion and unwinds the DNA between the incisions, displacing the damaged oligonucleotide. The resulting gap is then filled by DNA polymerase I and ligase, completing repair.

UvrD also participates in mismatch repair. In the MutHLS-dependent pathway, it associates with MutL and MutS and is loaded at a nick to translocate 3' to 5', unwinding and removing the newly synthesized strand that contains the mismatch. This provides a template for accurate resynthesis by the DNA polymerase and subsequent ligation.

Beyond these pathways, UvrD is implicated in replication fork maintenance and restart, as well as certain recombination- and transcription-coupled repair processes. Its activity can remodel protein–DNA complexes and assist in clearing obstacles to replication.

Molecular characteristics include its status as a SF1 helicase with two RecA-like motor domains and conserved ATPase motifs. UvrD activity can occur as a monomer or a dimer, depending on substrate and cellular context. Its function is essential for genome stability in many bacteria, and homologs are widespread; in Bacillus and related species the functional analog is often called PcrA.