A conserved 3'----5' exonuclease active site in prokaryotic and eukaryotic DNA polymerases

Cell. 1989 Oct 6;59(1):219-28. doi: 10.1016/0092-8674(89)90883-0.


The 3'----5' exonuclease active site of E. coli DNA polymerase I is predicted to be conserved for both prokaryotic and eukaryotic DNA polymerases based on amino acid sequence homology. Three amino acid regions containing the critical residues in the E. coli DNA polymerase I involved in metal binding, single-stranded DNA binding, and catalysis of the exonuclease reaction are located in the amino-terminal half and in the same linear arrangement in several prokaryotic and eukaryotic DNA polymerases. Site-directed mutagenesis at the predicted exonuclease active site of the phi 29 DNA polymerase, a model enzyme for prokaryotic and eukaryotic alpha-like DNA polymerases, specifically inactivated the 3'----5' exonuclease activity of the enzyme. These results reflect a high evolutionary conservation of this catalytic domain. Based on structural and functional data, a modular organization of enzymatic activities in prokaryotic and eukaryotic DNA polymerases is also proposed.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Binding Sites
  • Cells / enzymology*
  • DNA-Directed DNA Polymerase / metabolism*
  • DNA-Directed DNA Polymerase / physiology
  • Deoxyribonucleases / genetics
  • Deoxyribonucleases / metabolism*
  • Deoxyribonucleases / physiology
  • Eukaryotic Cells / enzymology*
  • Eukaryotic Cells / physiology
  • Molecular Sequence Data
  • Mutation
  • Prokaryotic Cells / enzymology*
  • Prokaryotic Cells / physiology
  • Sequence Homology, Nucleic Acid


  • DNA-Directed DNA Polymerase
  • Deoxyribonucleases
  • deoxyribonuclease A