Isolation and partial characterization of a mutant of Escherichia coli deficient in DNA polymerase II

Proc Natl Acad Sci U S A. 1972 Aug;69(8):2090-4. doi: 10.1073/pnas.69.8.2090.


A mutant of Escherichia coli deficient in DNA polymerase II has been isolated from E. coli polA1 by mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine and assay of polymerase activity in extracts of survivors. The polA1 mutation was suppressed during mutagenesis by introduction of the suppressor, su7(+), into the parental strain. The mutant, HMS83 polA1 polB1, contains less than 0.5% of the normal levels of DNA polymerase II. The only polymerase activity detected in the mutant is DNA polymerase III. E. coli HMS83 grows normally at both 25 and 42 degrees , and supports the growth of bacteriophages T4, T7, lambda, varphiX174, 186, P2, and fd. The polB mutation does not affect sensitivity to ultraviolet irradiation or recombination frequencies.

MeSH terms

  • Cell Fractionation
  • Cell Survival / radiation effects
  • Chromatography, DEAE-Cellulose
  • DNA Nucleotidyltransferases / analysis*
  • DNA Nucleotidyltransferases / isolation & purification
  • DNA, Bacterial / biosynthesis*
  • Escherichia coli / enzymology*
  • Escherichia coli / radiation effects
  • Guanidines / pharmacology*
  • Maltose / metabolism
  • Methods
  • Mutagens / pharmacology
  • Mutation / drug effects*
  • Nitroso Compounds / pharmacology*
  • Nitrosoguanidines / pharmacology
  • Proteins / analysis
  • Radiation Effects
  • Recombination, Genetic
  • Transduction, Genetic
  • Ultraviolet Rays


  • DNA, Bacterial
  • Guanidines
  • Mutagens
  • Nitroso Compounds
  • Nitrosoguanidines
  • Proteins
  • Maltose
  • DNA Nucleotidyltransferases