Mismatch-specific 3'----5' exonuclease associated with the mitochondrial DNA polymerase from Drosophila embryos

Proc Natl Acad Sci U S A. 1989 Sep;86(17):6469-73. doi: 10.1073/pnas.86.17.6469.

Abstract

The mitochondrial DNA polymerase from Drosophila embryos lacks dNTP turnover activity. However, a potent 3'----5' exonuclease activity can be detected by a specific assay in which the exonuclease excises mispaired nucleotides at the 3' termini of primed synthetic and natural DNA templates. The excision of a mispaired nucleotide occurs at a significantly greater rate than excision of a correctly paired nucleotide and, under conditions of DNA synthesis, hydrolysis of a mispaired terminal nucleotide occurs prior to primer extension. The 3'----5' exonuclease copurifies quantitatively with DNA polymerase gamma and cosediments with the nearly homogeneous enzyme under native conditions. These results suggest that the 3'----5' exonuclease provides a proofreading function to enhance the fidelity of DNA synthesis during Drosophila mitochondrial DNA replication.

Publication types

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

MeSH terms

  • Animals
  • DNA Polymerase I / metabolism
  • DNA Polymerase III / metabolism
  • DNA Replication
  • DNA, Mitochondrial / genetics*
  • DNA-Directed DNA Polymerase / isolation & purification
  • DNA-Directed DNA Polymerase / metabolism*
  • Drosophila / embryology
  • Embryo, Nonmammalian / enzymology
  • Escherichia coli / enzymology
  • Exodeoxyribonuclease V
  • Exodeoxyribonucleases / isolation & purification
  • Exodeoxyribonucleases / metabolism*
  • Kinetics
  • Mitochondria / enzymology*
  • Substrate Specificity

Substances

  • DNA, Mitochondrial
  • DNA Polymerase I
  • DNA Polymerase III
  • DNA-Directed DNA Polymerase
  • Exodeoxyribonucleases
  • Exodeoxyribonuclease V