The RuvAB branch migration complex can displace topoisomerase IV.quinolone.DNA ternary complexes

J Biol Chem. 2003 Nov 28;278(48):48485-90. doi: 10.1074/jbc.M304217200. Epub 2003 Sep 17.

Abstract

Quinolone antimicrobial drugs target both DNA gyrase and topoisomerase IV (Topo IV) and convert these essential enzymes into cellular poisons. Topoisomerase poisoning results in the inhibition of DNA replication and the generation of double-strand breaks. Double-strand breaks are repaired by homologous recombination. Here, we have investigated the interaction between the RuvAB branch migration complex and the Topo IV.quinolone.DNA ternary complex. A strand-displacement assay is employed to assess the helicase activity of the RuvAB complex in vitro. RuvAB-catalyzed strand displacement requires both RuvA and RuvB proteins, and it is stimulated by a 3'-non-hybridized tail. Interestingly, Topo IV.quinolone.DNA ternary complexes do not inhibit the translocation of the RuvAB complex. In fact, Topo IV.quinolone.DNA ternary complexes are reversed and displaced from the DNA upon their collisions with the RuvAB complex. These results suggest that the RuvAB branch migration complex can actively remove quinolone-induced covalent topoisomerase.DNA complexes from DNA and complete the homologous recombination process in vivo.

Publication types

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

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism*
  • Catalysis
  • DNA / chemistry*
  • DNA Helicases*
  • DNA Topoisomerase IV / chemistry*
  • DNA Topoisomerase IV / metabolism
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / metabolism*
  • Dose-Response Relationship, Drug
  • Enzyme Inhibitors / pharmacology
  • Escherichia coli / metabolism
  • Escherichia coli Proteins
  • Models, Genetic
  • Norfloxacin / pharmacology
  • Protein Binding
  • Protein Transport
  • Quinolones / chemistry*
  • Recombination, Genetic
  • Time Factors

Substances

  • Bacterial Proteins
  • DNA-Binding Proteins
  • Enzyme Inhibitors
  • Escherichia coli Proteins
  • Quinolones
  • RuvB protein, Bacteria
  • DNA
  • Holliday junction DNA helicase, E coli
  • DNA Helicases
  • DNA Topoisomerase IV
  • Norfloxacin