title: Site-specifically modified oligodeoxyribonucleotides as templates for Escherichia coli DNA polymerase I.
abstract: 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.
mesh_terms: D001483:Base Sequence; D004256:DNA Polymerase I / Q000378:metabolism*; D004260:DNA Repair; D004926:Escherichia coli / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology; D009154:Mutation; D009838:Oligodeoxyribonucleotides; D009876:Operon; D014176:Protein Biosynthesis; D013379:Substrate Specificity
chemical_list: D009838:Oligodeoxyribonucleotides; D004256:DNA Polymerase I; D008274:Magnesium