Strand exchange through a DNA-protein complex requires a DNA helicase.
The phage T4 uvsX and gene 32 proteins are capable of mediating homologous strand exchange, a central reaction in general genetic recombination, in vitro using naked DNA substrates. However, strand exchange is blocked by a sequence specific DNA-protein complex. Since protein-complexed substrates must be employed in vivo, this suggests that another factor(s) is required for strand exchange with protein-complexed DNAs. We show here that a DNA helicase, the T4 dda protein, allows the phage recombination machinery to drive branch migration through a RNA polymerase-promoter complex. This is the first observation of in vitro strand exchange using protein-bound substrates. These results suggest that a DNA helicase is a necessary component of the "protein machine" that mediates recombination in vivo.
Salinas
F
F
Department of Chemistry and Biochemistry, University of Texas at Austin 78712.
Kodadek
T
T
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D017122:Bacteriophage T4 / Q000235:genetics / Q000378:metabolism; D004247:DNA / Q000378:metabolism*; D004265:DNA Helicases / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D005814:Genes, Viral; D008565:Membrane Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D014764:Viral Proteins / Q000378:metabolism*
D004268:DNA-Binding Proteins; D008565:Membrane Proteins; C092863:UvsX protein, Enterobacteria phage T4; D014764:Viral Proteins; C060035:gp32 protein, Enterobacteria phage T4; D004247:DNA; D012321:DNA-Directed RNA Polymerases; D000251:Adenosine Triphosphatases; D004265:DNA Helicases; C077401:dda DNA helicase protein, Bacteriophage T4