Relationship between cellular RecA protein concentration and untargeted mutagenesis in Escherichia coli

Mutat Res. 1986 May;160(3):179-93. doi: 10.1016/0027-5107(86)90127-2.


We measured the production of untargeted mutations in the cI and cII genes of untreated lambda phage undergoing a lytic cycle in UV-irradiated bacterial hosts. As previously shown, treatment with 4 micrograms/ml of rifampicin during post-irradiation incubation inhibited amplification of the RecA protein in these cells. In addition, we observed a decreased mutation rate compared to the untreated, irradiated bacteria. Treatment with 4 micrograms/ml or 8 micrograms/ml rifampicin did not prevent the UV induction of the umuDC operon, as judged by assay of beta-galactosidase activity in a umuC-lacZ fusion strain. In contrast, the UV-induction of beta-galactosidase in the sulA-lacZ fusion strain was decreased by 4 micrograms/ml rifampicin. The inhibition of untargeted mutagenesis by this drug treatment was also observed in a strain constitutive for SOS functions (lexA (Def)) as well as in a RecA-overproducing plasmid strain, suggesting the requirement of other factor(s) in wild-type recA+ cells. An htpR165-carrying strain, that blocks induction of heat-shock proteins, exhibited normal UV-promoted mutagenesis. A correlation was observed between the cellular concentration of RecA protein, increased spontaneously by a temperature shift in a lexA(Ts) strain, and the extent of UV-promoted untargeted mutagenesis. These results suggest a mechanistic role of RecA protein in this process.

Publication types

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

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / physiology
  • Bacteriophage lambda / genetics
  • Bacteriophage lambda / metabolism
  • Bacteriophage lambda / radiation effects
  • Escherichia coli / genetics*
  • Escherichia coli / metabolism
  • Genes, Bacterial / radiation effects
  • Genes, Viral / radiation effects
  • Heat-Shock Proteins / physiology
  • Mutation
  • Rec A Recombinases / analysis
  • Rec A Recombinases / physiology*
  • Rifampin / pharmacology
  • Temperature
  • Transcription, Genetic / drug effects
  • Transcription, Genetic / radiation effects
  • Ultraviolet Rays
  • Viral Proteins / genetics


  • Bacterial Proteins
  • Heat-Shock Proteins
  • Viral Proteins
  • Rec A Recombinases
  • Rifampin