excinuclease repair complex GO:0009380 UvrABC excinuclease complex cellular_component Any of the protein complexes formed by the UvrABC excinuclease system, which carries out nucleotide excision repair. Three different complexes are formed by the 3 proteins as they proceed through the excision repair process. First a complex consisting of two A subunits and two B subunits bind DNA and unwind it around the damaged site. Then, the A subunits disassociate leaving behind a stable complex between B subunits and DNA. Now, subunit C binds to this B+DNA complex and causes subunit B to nick the DNA on one side of the complex while subunit C nicks the DNA on the other side of the complex. DNA polymerase I and DNA ligase can then repair the resulting gap. excinuclease ABC complex endodeoxyribonuclease complex DNA repair complex