UvrD limits the number and intensities of RecA-green fluorescent protein structures in Escherichia coli K-12

J Bacteriol. 2007 Apr;189(7):2915-20. doi: 10.1128/JB.01777-06. Epub 2007 Jan 26.

Abstract

RecA is important for recombination, DNA repair, and SOS induction. In Escherichia coli, RecBCD, RecFOR, and RecJQ prepare DNA substrates onto which RecA binds. UvrD is a 3'-to-5' helicase that participates in methyl-directed mismatch repair and nucleotide excision repair. uvrD deletion mutants are sensitive to UV irradiation, hypermutable, and hyper-rec. In vitro, UvrD can dissociate RecA from single-stranded DNA. Other experiments suggest that UvrD removes RecA from DNA where it promotes unproductive reactions. To test if UvrD limits the number and/or the size of RecA-DNA structures in vivo, an uvrD mutation was combined with recA-gfp. This recA allele allows the number of RecA structures and the amount of RecA at these structures to be assayed in living cells. uvrD mutants show a threefold increase in the number of RecA-GFP foci, and these foci are, on average, nearly twofold higher in relative intensity. The increased number of RecA-green fluorescent protein foci in the uvrD mutant is dependent on recF, recO, recR, recJ, and recQ. The increase in average relative intensity is dependent on recO and recQ. These data support an in vivo role for UvrD in removing RecA from the DNA.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • DNA Helicases / genetics
  • DNA Helicases / metabolism*
  • DNA, Bacterial / genetics
  • DNA, Bacterial / metabolism
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Escherichia coli K12 / enzymology
  • Escherichia coli K12 / metabolism*
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism*
  • Green Fluorescent Proteins / metabolism*
  • Molecular Sequence Data
  • Mutagenesis
  • Rec A Recombinases / genetics*
  • Rec A Recombinases / metabolism*
  • Recombinant Fusion Proteins / metabolism

Substances

  • DNA, Bacterial
  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • Recombinant Fusion Proteins
  • recF protein, E coli
  • Green Fluorescent Proteins
  • Rec A Recombinases
  • UvrD protein, E coli
  • DNA Helicases

Associated data

  • GENBANK/AY994192