Proofreading deficiency of Pol I increases the levels of spontaneous rpoB mutations in E. coli

Mutat Res. 2011 Jul 1;712(1-2):28-32. doi: 10.1016/j.mrfmmm.2011.03.011. Epub 2011 Apr 1.

Abstract

The fidelity role of DNA polymerase I in chromosomal DNA replication in E. coli was investigated using the rpoB forward target. These experiments indicated that in a strain carrying a proofreading-exonuclease-defective form of Pol I (polAexo mutant) the frequency of rpoB mutations increased by about 2-fold, consistent with a model that the fidelity of DNA polymerase I is important in controlling the overall fidelity of chromosomal DNA replication. DNA sequencing of rpoB mutants revealed that the Pol I exonuclease deficiency lead to an increase in a variety of base-substitution mutations. A polAexo mutator effect was also observed in strains defective in DNA mismatch repair and carrying the dnaE915 antimutator allele. Overall, the data are consistent with a proposed role of Pol I in the faithful completion of Okazaki fragment gaps at the replication fork.

Publication types

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

MeSH terms

  • DNA
  • DNA Mismatch Repair
  • DNA Polymerase I / genetics*
  • DNA Replication*
  • DNA, Bacterial
  • DNA-Directed RNA Polymerases
  • Drug Resistance, Bacterial / genetics
  • Escherichia coli / genetics*
  • Escherichia coli Proteins / adverse effects*
  • Escherichia coli Proteins / genetics*
  • Mutation*
  • Rifampin / pharmacology

Substances

  • DNA, Bacterial
  • Escherichia coli Proteins
  • Okazaki fragments
  • rpoB protein, E coli
  • DNA
  • DNA-Directed RNA Polymerases
  • DNA Polymerase I
  • Rifampin