Site-specifically modified oligodeoxyribonucleotides as templates for Escherichia coli DNA polymerase I

Proc Natl Acad Sci U S A. 1985 Apr;82(8):2325-9. doi: 10.1073/pnas.82.8.2325.


Oligodeoxyribonucleotides with site-specific modifications have been used as substrates for Escherichia coli DNA polymerase I holoenzyme and Klenow fragment. Modifications included the bulky guanine-8-aminofluorene adduct and a guanine oxidation product resembling the product of photosensitized DNA oxidation. By a combination of primers and "nick-mers", conditions of single-strand-directed DNA synthesis and nick-translation could be created. Our results show that the polymerase can bypass both types of lesions. Bypass occurs on a single-stranded template but is facilitated on a nicked, double-stranded template. Only purines, with guanine more favored than adenine, are incorporated across both lesions. Hesitation during bypass could not be detected. The results indicate that site-specifically modified oligonucleotides can be sensitive probes for the action of polymerases on damaged templates. They also suggest a function for polymerase I, in its nick-translation capacity, during DNA repair and mutagenesis.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Base Sequence
  • DNA Polymerase I / metabolism*
  • DNA Repair
  • Escherichia coli / metabolism*
  • Magnesium / pharmacology
  • Mutation
  • Oligodeoxyribonucleotides
  • Operon
  • Protein Biosynthesis
  • Substrate Specificity


  • Oligodeoxyribonucleotides
  • DNA Polymerase I
  • Magnesium