On the fidelity of deoxyribonucleic acid synthesis directed by chromatin-associated deoxyribonucleic acid polymerase beta

Biochemistry. 1980 Dec 9;19(25):5939-46. doi: 10.1021/bi00566a043.


Accuracy of poly[d(A-T)] synthesis catalyzed by chromatin-bound deoxyribonucleic acid (DNA) polymerase beta was measured with several types. A new procedure was developed for the isolation of copied poly[d(A-T)] from chromatin DNA. This method involved in vitro copying of poly[d(A-T)] by native chromatin and subsequent selective fragmentation of chromatin by restriction nucleases, proteinase K, and heat denaturation. The fragmented natural DNA is then separated from the high molecular weight poly[d(A-T)] by gel filtration. The efficacy of DNA removal by this procedure was validated by cesium chloride gradient and nearest-neighbor analysis of the product of the reaction and by measurement of the fidelity of poly[d(A-T)] synthesis by Escherichia coli DNA Pol I contaminated with increasing amounts of DNA. Also, DNA polymerases dissociated from chromatin retain the same accuracy as that of native chromatin. Synthesis of poly[d(A-T)] by chromatin is catalyzed mainly by DNA polymerase-beta. By use of the described technique, we find that the fidelity of this reaction is exceptionally low; approximately one dGTP was incorporated for every thousand complementary nucleotides polymerized.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Chromatin / enzymology*
  • DNA Polymerase I / metabolism*
  • DNA Replication / drug effects
  • DNA Restriction Enzymes
  • DNA-Directed DNA Polymerase / metabolism*
  • Dactinomycin / pharmacology
  • Escherichia coli / enzymology
  • HeLa Cells / enzymology
  • Humans
  • Liver / enzymology
  • Lymphocyte Activation
  • Lymphocytes / enzymology
  • Male
  • Mice
  • Mice, Inbred Strains


  • Chromatin
  • Dactinomycin
  • DNA Polymerase I
  • DNA-Directed DNA Polymerase
  • DNA Restriction Enzymes