Resolution of converging replication forks by RecQ and topoisomerase III.
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.
Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA.
Catherine
C
Suski
Kenneth J
KJ
Marians
D004261:DNA Replication; D042522:DNA Replication Timing; D004264:DNA Topoisomerases, Type I / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D029968:Escherichia coli Proteins / Q000378:metabolism; D016680:Genome, Bacterial; D007700:Kinetics; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D053484:RecQ Helicases / Q000235:genetics / Q000378:metabolism*; D016196:S Phase
D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D053484:RecQ Helicases; D004264:DNA Topoisomerases, Type I