Autonomous 3'-->5' exonucleases can proofread for DNA polymerase beta from rat liver

Mutat Res. 2000 Apr 28;459(3):237-42. doi: 10.1016/s0921-8777(00)00004-5.


Autonomous 3'-->5'exonucleases are not bound covalently to DNA polymerases but are often involved in replicative complexes. Such exonucleases from rat liver, calf thymus and Escherichia coli (molecular masses of 28+/-2 kDa) are shown to increase more than 10-fold the accuracy of DNA polymerase beta (the most inaccurate mammalian polymerase) from rat liver in the course of reduplication of the primed DNA of bacteriophage phiX174 amber 3 in vitro. The extent of correction increases together with the rise in 3'-->5' exonuclease concentration. Extrapolation of the in vitro DNA replication fidelity to the cellular levels of rat exonuclease and beta-polymerase suggests that exonucleolytic proofreading could augment the accuracy of DNA synthesis by two orders of magnitude. These results are not explained by exonucleolytic degradation of the primers ("no synthesis-no errors"), since similar data are obtained with the use of the primers 15 or 150 nucleotides long in the course of a fidelity assay of DNA polymerases, both alpha and beta, in the presence of various concentrations of 3'-->5' exonuclease.

MeSH terms

  • Animals
  • Bacteriophage phi X 174 / enzymology
  • Cattle
  • Chromatin / chemistry
  • Chromatography, Gel
  • Cytosol / chemistry
  • Cytosol / enzymology
  • DNA Polymerase I / metabolism
  • DNA Polymerase beta / metabolism*
  • DNA Repair*
  • DNA Replication / drug effects
  • Deoxyguanine Nucleotides / chemistry
  • Electrophoresis, Polyacrylamide Gel
  • Escherichia coli / chemistry
  • Escherichia coli / enzymology
  • Exodeoxyribonuclease V
  • Exodeoxyribonucleases / isolation & purification
  • Exodeoxyribonucleases / metabolism*
  • Exodeoxyribonucleases / pharmacology
  • Liver / chemistry
  • Liver / enzymology*
  • Male
  • Molecular Weight
  • Mutagenicity Tests
  • Rats
  • Regression Analysis
  • Thymus Gland / chemistry
  • Thymus Gland / enzymology
  • Transcription, Genetic / drug effects


  • Chromatin
  • Deoxyguanine Nucleotides
  • 2'-deoxyguanosine 5'-phosphate
  • deoxyguanosine triphosphate
  • DNA Polymerase I
  • DNA Polymerase beta
  • Exodeoxyribonucleases
  • Exodeoxyribonuclease V