DNA damage by peplomycin and its repair in an in vitro system

Abstract

1. 1. DNA damage by peplomycin, an antitumor antibiotic, and its repair by cellular enzymes were studied using pUC18 plasmid DNA. The DNA damage and repair were measured by monitoring the conformational changes of pUCIS DNA. 2. 2. Peplomycin-induced DNA damage was enhanced by addition of ferrous ion and inhibited by deferoxamine, a specific iron chelator, suggesting iron-requirement for the DNA damage. 3. 3. DNA damage by peplomycin was inhibited by superoxide dismutase in both native and heatinactivated forms, possibly due to non-enzymatic interaction. 4. 4. Peplomycin-induced, single-strand breaks in pUCIS DNA was repaired by incubating with a priming factor (an exonuclease purified from mouse ascites sarcoma cells), DNA polymerase β, four deoxynucleoside triphosphates, T4 DNA ligase and ATP. The average repair patch size was estimated to be approximately four nucleotide length.