Enzymatic Repair of UV-Irradiated DNA in Vitro
Excision repair of UV-damaged Bacillus subtilis transforming DNA has been carried out by a sequential enzyme system in vitro. Incision adjacent to the pyrimidine dimer in the DNA strand by correndonuclease II-initiated excision of the damage by the 5′→3′-directed exonuclease of the Micrococcus luteus DNA polymerase. Reinsertion of nucleotides into the gap in the strand by the DNA polymerase at 10°C terminated in a single-strand break which was sealed by a polynucleotide ligase, thereby repairing the DNA strand. This restored biological activity to damaged DNA up to doses resulting in 60% inactivation of transforming activity. At higher doses, less repair was achieved, due to the development of double-strand breaks during the in vitro incision and excision steps.
KeywordsMicrococcus Luteus Pyrimidine Dimer Sucrose Gradient Centrifugation Deoxyribonucleoside Triphosphate Repair Condition
Unable to display preview. Download preview PDF.