Cisplatin induces DNA double-strand break formation in Escherichia coli dam mutants [An article from: DNA Repair]

This digital document is a journal article from DNA Repair, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Escherichia coli dam cells are more susceptible to the cytotoxic action of cisplatin than wildtype. Dam mutS or dam mutL bacteria, however, are resistant to this agent indicating that active mismatch repair sensitizes dam cells to cisplatin toxicity. Genetic data, obtained previously, were consistent with the generation and repair of cisplatin-induced double-strand breaks (DSBs). We measured DSB formation in temperature-sensitive dam recB mutants, after exposure to cisplatin, using pulse field gel electrophoresis and observed an increase in linear 100-300kb DNA fragments corresponding to approximately 15-45 double strand breaks per genome. The formation of these DSBs was temperature and dose-dependent and was decreased in recBC bacteria at the permissive temperature or in dam^+ or mutS control strains. There was a three-fold increase in circa 2mb linear chromosomal fragments in dam recBC strains at the non-permissive temperature compared to recBC alone. We show that dam priA strains are not viable suggesting that DSB formation is dependent on DNA replication restart. The sensitivity of priA mutants to cisplatin is also consistent with this conclusion.