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Bacteriophage T4 UvsW protein is a helicase involved in recombination, repair and the regulation of DNA replication origins
Author(s) -
CarlesKinch Kelly,
George James W.,
Kreuzer Kenneth N.
Publication year - 1997
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/16.13.4142
Subject(s) - biology , helicase , control of chromosome duplication , dna replication , rna helicase a , replication protein a , origin recognition complex , dna repair , homologous recombination , dna , microbiology and biotechnology , eukaryotic dna replication , genetics , rna , dna binding protein , gene , transcription factor
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.