title: Interplay between DNA replication, recombination and repair based on the structure of RecG helicase.
abstract: Recent studies in Escherichia coli indicate that the interconversion of DNA replication fork and Holliday junction structures underpins chromosome duplication and helps secure faithful transmission of the genome from one generation to the next. It facilitates interplay between DNA replication, recombination and repair, and provides means to rescue replication forks stalled by lesions in or on the template DNA. Insight into how this interconversion may be catalysed has emerged from genetic, biochemical and structural studies of RecG protein, a member of superfamily 2 of DNA and RNA helicases. We describe how a single molecule of RecG might target a branched DNA structure and translocate a single duplex arm to drive branch migration of a Holliday junction, interconvert replication fork and Holliday junction structures and displace the invading strand from a D loop formed during recombination at a DNA end. We present genetic evidence suggesting how the latter activity may provide an efficient pathway for the repair of DNA double-strand breaks that avoids crossing over, thus facilitating chromosome segregation at cell division.
authors.affiliation: Institute of Genetics, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK.
authors.forename: Geoffrey S
authors.initials: GS
authors.lastname: Briggs
authors.forename: Akeel A
authors.initials: AA
authors.lastname: Mahdi
authors.forename: Geoffrey R
authors.initials: GR
authors.lastname: Weller
authors.forename: Qin
authors.initials: Q
authors.lastname: Wen
authors.forename: Robert G
authors.initials: RG
authors.lastname: Lloyd
mesh_terms: D020090:Chromosome Segregation / Q000502:physiology*; D004247:DNA / Q000378:metabolism; D004265:DNA Helicases / Q000737:chemistry* / Q000378:metabolism; D004260:DNA Repair / Q000502:physiology*; D004261:DNA Replication / Q000502:physiology*; D045566:DNA, Cruciform / Q000378:metabolism; D004926:Escherichia coli; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D011995:Recombination, Genetic / Q000502:physiology*
chemical_list: D045566:DNA, Cruciform; D029968:Escherichia coli Proteins; C071446:RecG protein, E coli; D004247:DNA; D004265:DNA Helicases