A model for SOS-lesion-targeted mutations in Escherichia coli

Nature. 2001 Jan 18;409(6818):366-70. doi: 10.1038/35053116.


The UmuD'2C protein complex (Escherichia coli pol V) is a low-fidelity DNA polymerase (pol) that copies damaged DNA in the presence of RecA, single-stranded-DNA binding protein (SSB) and the beta,gamma-processivity complex of E. coli pol III (ref. 4). Here we propose a model to explain SOS-lesion-targeted mutagenesis, assigning specific biochemical functions for each protein during translesion synthesis. (SOS lesion-targeted mutagenesis occurs when pol V is induced as part of the SOS response to DNA damage and incorrectly incorporates nucleotides opposite template lesions.) Pol V plus SSB catalyses RecA filament disassembly in the 3' to 5' direction on the template, ahead of the polymerase, in a reaction that does not involve ATP hydrolysis. Concurrent ATP-hydrolysis-driven filament disassembly in the 5' to 3' direction results in a bidirectional stripping of RecA from the template strand. The bidirectional collapse of the RecA filament restricts DNA synthesis by pol V to template sites that are proximal to the lesion, thereby minimizing the occurrence of untargeted mutations at undamaged template sites.

Publication types

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

MeSH terms

  • Adenosine Triphosphate / analogs & derivatives*
  • Adenosine Triphosphate / metabolism
  • Catalysis
  • DNA, Bacterial / genetics*
  • DNA, Bacterial / metabolism
  • DNA-Binding Proteins / metabolism
  • DNA-Directed DNA Polymerase / metabolism
  • Deoxyribonuclease I / metabolism
  • Escherichia coli / genetics*
  • Escherichia coli Proteins
  • Models, Genetic
  • Mutagenesis*
  • Rec A Recombinases / metabolism
  • SOS Response, Genetics*


  • DNA, Bacterial
  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • adenosine 5'-O-(3-thiotriphosphate)
  • Adenosine Triphosphate
  • Rec A Recombinases
  • DNA polymerase V, E coli
  • DNA-Directed DNA Polymerase
  • Deoxyribonuclease I