A coproofreading Zn(2+)-dependent exonuclease within a bacterial replicase

Nat Struct Mol Biol. 2006 May;13(5):458-9. doi: 10.1038/nsmb1078. Epub 2006 Apr 9.

Abstract

The proofreading exonucleases of all DNA replicases contain acidic residues that chelate two Mg(2+) ions that participate in catalysis. DNA polymerase III holoenzymes contain their proofreading activity in a separate subunit, epsilon, which binds the polymerase subunit, alpha, through alpha's N-terminal php domain. Here we demonstrate that the alpha php domain contains a novel Zn(2+)-dependent 3' --> 5' exonuclease that preferentially removes mispaired nucleotides, providing the first example of a coediting nuclease.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Cations, Divalent / chemistry
  • DNA-Directed DNA Polymerase / metabolism*
  • Enzyme Stability
  • Exonucleases / metabolism*
  • Protein Subunits / metabolism
  • Thermus thermophilus / drug effects
  • Thermus thermophilus / enzymology
  • Zinc / chemistry
  • Zinc / pharmacology*

Substances

  • Cations, Divalent
  • Protein Subunits
  • DNA replicase
  • DNA-Directed DNA Polymerase
  • Exonucleases
  • Zinc