Rep helicase is a single-stranded DNA-dependent ATPase involved in DNA replication; it can initiate unwinding at a nick in the DNA. It binds to the single-stranded DNA and acts in a progressive fashion along the DNA in the 3' to 5' direction. ATP + H2O = ADP + H(+) + phosphate Homodimer. Belongs to the helicase family. UvrD subfamily.