Double-strand-break repair recombination in Escherichia coli: physical evidence for a DNA replication mechanism in vivo

Genes Dev. 1999 Nov 1;13(21):2889-903. doi: 10.1101/gad.13.21.2889.


DNA double-strand-break repair (DSBR) is, in many organisms, accomplished by homologous recombination. In Escherichia coli DSBR was thought to result from breakage and reunion of parental DNA molecules, assisted by known endonucleases, the Holliday junction resolvases. Under special circumstances, for example, SOS induction, recombination forks were proposed to initiate replication. We provide physical evidence that this is a major alternative mechanism in which replication copies information from one chromosome to another generating recombinant chromosomes in normal cells in vivo. This alternative mechanism can occur independently of known Holliday junction cleaving proteins, requires DNA polymerase III, and produces recombined DNA molecules that carry newly replicated DNA. The replicational mechanism underlies about half the recombination of linear DNA in E. coli; the other half occurs by breakage and reunion, which we show requires resolvases, and is replication-independent. The data also indicate that accumulation of recombination intermediates promotes replication dramatically.

Publication types

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

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • DNA Damage
  • DNA Polymerase III / metabolism
  • DNA Repair*
  • DNA Replication*
  • DNA, Bacterial / biosynthesis*
  • Endodeoxyribonucleases / genetics
  • Endodeoxyribonucleases / metabolism
  • Escherichia coli / genetics*
  • Escherichia coli Proteins*
  • Exodeoxyribonuclease V
  • Exodeoxyribonucleases / genetics
  • Exodeoxyribonucleases / metabolism
  • Recombinases
  • Recombination, Genetic*
  • Transposases / genetics
  • Transposases / metabolism


  • Bacterial Proteins
  • DNA, Bacterial
  • Escherichia coli Proteins
  • Recombinases
  • ruvC protein, E coli
  • RecG protein, E coli
  • Transposases
  • DNA Polymerase III
  • Endodeoxyribonucleases
  • Exodeoxyribonucleases
  • Exodeoxyribonuclease V