DNA polymerase I-mediated ultraviolet repair synthesis in toluene-treated Escherichia coli

J. W. Dorson, R. E. Moses

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


DNA synthesis after ultraviolet irradiation is low in wild type toluene-treated cells, The level of repair incorporation is greater in strains deficient in DNA polymerase I. The low level of repair synthesis is attributable to the concerted action of DNA polymerase 1 and polynucleotide ligase. Repair synthesis is stimulated by blocking ligase activity with the addition of nicotinamide mononucleotide (NMN) or the use of a ligase temperature-sensitive mutant. NMN stimulation is specific for DNA polymerase I-mediated repair synthesis, as it is absent in isogenic strains deficient in the polymerase function or the 5' → 3' exonuclease function associated with DNA polymerase I. DNA synthesis that is stimulated by NMN is proportional to the ultraviolet exposure at low doses, nonconservative in nature, and is dependent on the uvrA gene product but is independent of the recA gene product. These criteria place this synthesis in the excision repair pathway. The NMN-stimulated repair synthesis requires ATP and is N-ethylmaleimide- resistant. The use of NMN provides a direct means for evaluating the involvement of DNA polymerase I in excision repair.

Original languageEnglish (US)
Pages (from-to)665-670
Number of pages6
JournalJournal of Biological Chemistry
Issue number3
StatePublished - 1978

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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