title: Bacteriophage T4 UvsW protein is a helicase involved in recombination, repair and the regulation of DNA replication origins.
abstract: Bacteriophage T4 UvsW protein is involved in phage recombination, repair and the regulation of replication origins. Here, we provide evidence that UvsW functions as a helicase. First, expression of UvsW allows growth of an (otherwise inviable) Escherichia coli recG rnhA double mutant, consistent with UvsW being a functional analog of the RecG helicase. Second, UvsW contains helicase sequence motifs, and a substitution (K141R) in the Walker 'A' motif prevents growth of the E.coli recG rnhA double mutant. Third, UvsW, but not UvsW-K141R, inhibits replication from a T4 origin at which persistent RNA-DNA hybrids form and presumably trigger replication initiation. Fourth, mutations that inactivate UvsW and endonuclease VII (which cleaves DNA branches) synergistically block repair of double-strand breaks. These in vivo results are consistent with a model in which UvsW is a DNA helicase that catalyzes branch migration and dissociation of RNA-DNA hybrids. In support of this model, a partially purified GST/UvsW fusion protein, but not a GST/UvsW-K141R fusion, displays ssDNA-dependent ATPase activity and is able to unwind a branched DNA substrate.
authors.affiliation: Duke University Medical Center, Department of Microbiology and Program in Cell and Molecular Biology, Durham, NC 27710, USA.
authors.forename: K
authors.initials: K
authors.lastname: Carles-Kinch
authors.forename: J W
authors.initials: JW
authors.lastname: George
authors.forename: K N
authors.initials: KN
authors.lastname: Kreuzer
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics; D017122:Bacteriophage T4 / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D004247:DNA / Q000378:metabolism; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair; D004277:DNA, Single-Stranded; D004706:Endodeoxyribonucleases / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000821:virology; D029968:Escherichia coli Proteins; D005982:Glutathione Transferase / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D018741:Replication Origin; D016914:Ribonuclease H / Q000235:genetics; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D001426:Bacterial Proteins; D004277:DNA, Single-Stranded; D029968:Escherichia coli Proteins; D011993:Recombinant Fusion Proteins; D014764:Viral Proteins; C071446:RecG protein, E coli; D004247:DNA; D005982:Glutathione Transferase; D004706:Endodeoxyribonucleases; C035571:endodeoxyribonuclease VII; D016914:Ribonuclease H; C078856:ribonuclease HI; D000251:Adenosine Triphosphatases; D004265:DNA Helicases; C107414:UvsW protein, Bacteriophage T4