title: Stimulation of protein-directed strand exchange by a DNA helicase.
abstract: The protein-mediated exchange of strands between a DNA double helix and a homologous DNA single strand involves both synapsis and branch migration, which are two important aspects of any general recombination reaction. Purified DNA-dependent ATPases from Escherichia coli (recA protein), Ustilago (rec 1 protein) and phage T4 (uvsX protein) have been shown to drive both synapsis and branch migration in vitro. The T4 gene 32 protein is a helix-destabilizing protein that greatly stimulates uvsX-protein-catalysed synapsis, and the E. coli SSB (single-strand binding) protein stimulates the analogous recA-protein-mediated reaction to a lesser degree. One suspects that several other proteins also play a role in the strand exchange process. For example, a DNA helicase could in principle accelerate branch migration rates by helping to melt the helix at the branch point. The T4 dda protein is a DNA helicase that is required to move the T4 replication fork past DNA template-bound proteins in vitro. Previously, we have shown that the dda protein binds to a column that contains immobilized T4 uvsX protein. We show here that this helicase specifically stimulates the branch migration reaction that the uvsX protein catalyses as a central part of the genetic recombination process in a T4 bacteriophage-infected cell.
mesh_terms: D000251:Adenosine Triphosphatases / Q000502:physiology*; D004247:DNA / Q000378:metabolism; D004265:DNA Helicases / Q000502:physiology*; D004277:DNA, Single-Stranded / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000502:physiology*; D004338:Drug Combinations; D011995:Recombination, Genetic; D013604:T-Phages / Q000235:genetics*; D014764:Viral Proteins / Q000502:physiology*
chemical_list: D004277:DNA, Single-Stranded; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D004338:Drug Combinations; D014764:Viral Proteins; D004247:DNA; D000251:Adenosine Triphosphatases; D004265:DNA Helicases