Resolution of converging replication forks by RecQ and topoisomerase III

Mol Cell. 2008 Jun 20;30(6):779-89. doi: 10.1016/j.molcel.2008.04.020.

Abstract

RecQ-like DNA helicases pair with cognate topoisomerase III enzymes to function in the maintenance of genomic integrity in many organisms. These proteins play roles in stabilizing stalled replication forks, the S phase checkpoint response, and suppressing genetic crossovers, and their inactivation results in hyper-recombination, gross chromosomal rearrangements, chromosome segregation defects, and human disease. Biochemical activities associated with these enzymes include the ability to resolve double Holliday junctions, a process thought to lead to the suppression of crossover formation. Using Escherichia coli RecQ and topoisomerase III, we demonstrate a second activity for this pair of enzymes that could account for their role in maintaining genomic stability: resolution of converging replication forks. This resolution reaction is specific for the RecQ-topoisomerase III pair and is mediated by interaction of both of these enzymes with the single-stranded DNA-binding protein SSB.

Publication types

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

MeSH terms

  • DNA Replication Timing
  • DNA Replication*
  • DNA Topoisomerases, Type I / genetics
  • DNA Topoisomerases, Type I / metabolism*
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / genetics
  • Escherichia coli / enzymology
  • Escherichia coli / genetics
  • Escherichia coli Proteins / metabolism
  • Genome, Bacterial*
  • Kinetics
  • Models, Molecular
  • Nucleic Acid Conformation
  • RecQ Helicases / genetics
  • RecQ Helicases / metabolism*
  • S Phase

Substances

  • DNA, Bacterial
  • Escherichia coli Proteins
  • RecQ Helicases
  • DNA Topoisomerases, Type I