title: RuvABC is required to resolve holliday junctions that accumulate following replication on damaged templates in Escherichia coli.
abstract: RuvABC is a complex that promotes branch migration and resolution of Holliday junctions. Although ruv mutants are hypersensitive to UV irradiation, the molecular event(s) that necessitate RuvABC processing in vivo are not known. Here, we used a combination of two-dimensional gel analysis and electron microscopy to reveal that although ruvAB and ruvC mutants are able to resume replication following arrest at UV-induced lesions, molecules that replicate in the presence of DNA damage accumulate unresolved Holliday junctions. The failure to resolve the Holliday junctions on the fully replicated molecules correlates with a delayed loss of genomic integrity that is likely to account for the loss of viability in these cells. The strand exchange intermediates that accumulate in ruv mutants are distinct from those observed at arrested replication forks and are not subject to resolution by RecG. These results indicate that the Holliday junctions observed in ruv mutants are intermediates of a repair pathway that is distinct from that of the recovery of arrested replication forks. A model is proposed in which RuvABC is required to resolve junctions that arise during the repair of a subset of nonarresting lesions after replication has passed through the template.
authors.affiliation: Department of Biology, Portland State University, Portland, Oregon 97207, USA. donaldsonjr@niddk.nih.gov
authors.forename: Janet R
authors.initials: JR
authors.lastname: Donaldson
authors.forename: Charmain T
authors.initials: CT
authors.lastname: Courcelle
authors.forename: Justin
authors.initials: J
authors.lastname: Courcelle
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D004265:DNA Helicases / Q000235:genetics*; D004261:DNA Replication; D045566:DNA, Cruciform; D015180:Electrophoresis, Gel, Two-Dimensional; D004706:Endodeoxyribonucleases / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D008854:Microscopy, Electron; D009154:Mutation; D011995:Recombination, Genetic; D014466:Ultraviolet Rays
chemical_list: D001426:Bacterial Proteins; D045566:DNA, Cruciform; D029968:Escherichia coli Proteins; C061260:RuvB protein, Bacteria; C069806:ruvC protein, E coli; D004706:Endodeoxyribonucleases; C071059:Holliday junction DNA helicase, E coli; D004265:DNA Helicases