Role of the Escherichia coli RecQ DNA helicase in SOS signaling and genome stabilization at stalled replication forks

Genes Dev. 2004 Aug 1;18(15):1886-97. doi: 10.1101/gad.1223804.


The RecQ protein family is a highly conserved group of DNA helicases that play roles in maintaining genomic stability. In this study, we present biochemical and genetic evidence that Escherichia coli RecQ processes stalled replication forks and participates in SOS signaling. Cells that carry dnaE486, a mutation in the DNA polymerase III alpha-catalytic subunit, induce an RecA-dependent SOS response and become highly filamented at the semirestrictive temperature (38 degrees C). An recQ mutation suppresses the induction of SOS response and the filamentation in the dnaE486 mutant at 38 degrees C, causing appearance of a high proportion of anucleate cells. In vitro, RecQ binds and unwinds forked DNA substrates with a gap on the leading strand more efficiently than those with a gap on the lagging strand or Holliday junction DNA. RecQ unwinds the template duplex ahead of the fork, and then the lagging strand is unwound. Consequently, this process generates a single-stranded DNA (ssDNA) gap on the lagging strand adjacent to a replication fork. These results suggest that RecQ functions to generate an initiating signal that can recruit RecA for SOS induction and recombination at stalled replication forks, which are required for the cell cycle checkpoint and resumption of DNA replication.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / physiology*
  • DNA Helicases / physiology*
  • DNA Polymerase III / genetics
  • DNA Polymerase III / metabolism
  • DNA Replication*
  • DNA, Bacterial / genetics
  • DNA, Bacterial / metabolism
  • DNA, Single-Stranded / genetics
  • DNA, Single-Stranded / metabolism
  • Escherichia coli / enzymology*
  • Escherichia coli / genetics
  • Genome, Bacterial*
  • Mutation / genetics
  • RecQ Helicases
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Signal Transduction / physiology*
  • Son of Sevenless Proteins / metabolism*
  • Temperature


  • DNA, Bacterial
  • DNA, Single-Stranded
  • Recombinant Proteins
  • Son of Sevenless Proteins
  • DNA Polymerase III
  • Adenosine Triphosphatases
  • RecQ protein, E coli
  • DNA Helicases
  • RecQ Helicases