title: The T4 phage UvsW protein contains both DNA unwinding and strand annealing activities.
abstract: UvsW protein belongs to the SF2 helicase family and is one of three helicases found in T4 phage. UvsW governs the transition from origin-dependent to origin-independent replication through the dissociation of R-loops located at the T4 origins of replication. Additionally, in vivo evidence indicates that UvsW plays a role in recombination-dependent replication and/or DNA repair. Here, the biochemical properties of UvsW helicase are described. UvsW is a 3' to 5' helicase that unwinds a wide variety of substrates, including those resembling stalled replication forks and recombination intermediates. UvsW also contains a potent single-strand DNA annealing activity that is enhanced by ATP hydrolysis but does not require it. The annealing activity is inhibited by the non-hydrolysable ATP analog (adenosine 5'-O-(thiotriphosphate)), T4 single-stranded DNA-binding protein (gp32), or a small 8.8-kDa polypeptide (UvsW.1). Fluorescence resonance energy transfer experiments indicate that UvsW and UvsW.1 form a complex, suggesting that the UvsW helicase may exist as a heterodimer in vivo. Fusion of UvsW and UvsW.1 results in a 68-kDa protein having nearly identical properties as the UvsW-UvsW.1 complex, indicating that the binding locus of UvsW.1 is close to the C terminus of UvsW. The biochemical properties of UvsW are similar to the RecQ protein family and suggest that the annealing activity of these helicases may also be modulated by protein-protein interactions. The dual activities of UvsW are well suited for the DNA repair pathways described for leading strand lesion bypass and synthesis-dependent strand annealing.
authors.affiliation: Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Scott W
authors.initials: SW
authors.lastname: Nelson
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Benkovic
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry; D017122:Bacteriophage T4 / Q000737:chemistry*; D001483:Base Sequence; D003001:Cloning, Molecular; D004265:DNA Helicases / Q000737:chemistry* / Q000502:physiology*; D004260:DNA Repair; D031541:Fluorescence Resonance Energy Transfer; D006868:Hydrolysis; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation; D017434:Protein Structure, Tertiary; D011995:Recombination, Genetic; D014764:Viral Proteins / Q000737:chemistry* / Q000502:physiology*
chemical_list: D014764:Viral Proteins; D000255:Adenosine Triphosphate; D004265:DNA Helicases; C107414:UvsW protein, Bacteriophage T4