A study on the unprimed poly (dA-dT) synthesis catalyzed by preparations of E. coli DNA polymerase I

Nucleic Acids Res. 1979 Jun 11;6(7):2545-60. doi: 10.1093/nar/6.7.2545.


Evidence was obtained indicating that the initiation of poly (dA-dT) de novo synthesis is provided by deoxynucleoside diphosphate: oligonucleotide deoxynucleotidyl transferase (dNDP-transferase present in preparations of E. coli DNA polymerase I and capable of catalyzing the unprimed polymerization of dNDP. dNDP-transferase synthesyzes short oligonucleotides which form template-primer complexes repeatedly replicated by DNA polymerase I. This conclusion was based on the following observations: the abolition of the lag period of poly (dA-dT) synthesis by preincubation of DNA-polymerase I preparations with dADP and dTDP; the presence of oligo (dA-dT) among the preincubation products; the suppressive effect of dithiothreitol and N-ethylmaleimide (inhibitors of dNDP-transferase) on the de novo, but not on the primed synthesis of poly (dA-dT), catalyzed by preparations of DNA-polymerase I.

MeSH terms

  • DNA Polymerase I / metabolism*
  • DNA-Directed DNA Polymerase / metabolism*
  • Dithiothreitol / pharmacology
  • Escherichia coli / enzymology*
  • Ethylmaleimide / pharmacology
  • Kinetics
  • Poly dA-dT / biosynthesis*
  • Polydeoxyribonucleotides / biosynthesis*


  • Polydeoxyribonucleotides
  • Poly dA-dT
  • DNA Polymerase I
  • DNA-Directed DNA Polymerase
  • Ethylmaleimide
  • Dithiothreitol