Proofreading activity of DNA polymerase III responds like elongation activity to auxiliary subunits

J. A. Reems, M. A. Griep, C. S. McHenry

Research output: Contribution to journalArticle

3 Scopus citations


A comparison of the 3'→5' proofreading properties between Escherichia coli DNA polymerase III holoenzyme and DNA polymerase III' was conducted. This study indicated that the influence of the holoenzyme auxiliary subunits on the proofreading exonuclease parallels their effect on the elongation reaction. At physiological ionic strengths the auxiliary subunits markedly stimulated the exonuclease rate in an ATP-dependent reaction, while the exonuclease rate of DNA polymerase III' was not affected by ATP. E. coli single-stranded DNA binding protein stimulated the 3'→5' exonuclease activity of holoenzyme and inhibited DNA polymerase III'. Similarly, the auxiliary subunits and ATP converted the proofreading activity to a highly processive exonuclease. Our observation, that the exonuclease activity of the DNA polymerase III holoenzyme responded to ATP, salt, and E. coli single-stranded DNA-binding protein like the elongation activity, is consistent with the polymerase and exonuclease subunits acting within the same complex in a coordinated reaction.

Original languageEnglish (US)
Pages (from-to)4878-4882
Number of pages5
JournalJournal of Biological Chemistry
Issue number8
StatePublished - 1991

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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