title: Direct observation of stalled fork restart via fork regression in the T4 replication system.
abstract: The restart of a stalled replication fork is a major challenge for DNA replication. Depending on the nature of the damage, different repair processes might be triggered; one is template switching, which is a bypass of a leading-strand lesion via fork regression. Using magnetic tweezers to study the T4 bacteriophage enzymes, we have reproduced in vitro the complete process of template switching. We show that the UvsW DNA helicase in cooperation with the T4 holoenzyme can overcome leading-strand lesion damage by a pseudostochastic process, periodically forming and migrating a four-way Holliday junction. The initiation of the repair process requires partial replisome disassembly via the departure of the replicative helicase. The results support the role of fork regression pathways in DNA repair.
authors.affiliation: Departament de Física Fonamental, Facultat de Física, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain.
authors.forename: Maria
authors.initials: M
authors.lastname: Manosas
authors.forename: Senthil K
authors.initials: SK
authors.lastname: Perumal
authors.forename: Vincent
authors.initials: V
authors.lastname: Croquette
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Benkovic
mesh_terms: D017122:Bacteriophage T4 / Q000201:enzymology / Q000235:genetics*; D004249:DNA Damage; D004265:DNA Helicases / Q000378:metabolism*; D004260:DNA Repair; D004261:DNA Replication; D045566:DNA, Cruciform / Q000235:genetics; D004279:DNA, Viral / Q000235:genetics*; D004926:Escherichia coli / Q000821:virology; D020035:Holoenzymes / Q000378:metabolism; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: D045566:DNA, Cruciform; D004279:DNA, Viral; D020035:Holoenzymes; D014764:Viral Proteins; D004265:DNA Helicases; C107414:UvsW protein, Bacteriophage T4