title: Discovery of a predicted DNA knot substantiates a model for site-specific recombination.
abstract: The mechanism of site-specific genetic recombination mediated by Tn3 resolvase has been investigated by a topological approach. Extrapolation of a detailed model of synapsis and strand exchange predicts the formation of an additional DNA product with a specific knotted structure. Two-dimensional gel electrophoresis of DNA reacted in vitro revealed a product, about 0.1 percent of the total, with the appropriate mobility. A technique for determining DNA topology by electron microscopy was improved such that less than a nanogram of DNA was required. The structure of the knot was as predicted, providing strong evidence for the model and showing the power of the topological method.
authors.forename: S A
authors.initials: SA
authors.lastname: Wasserman
authors.forename: J M
authors.initials: JM
authors.lastname: Dungan
authors.forename: N R
authors.initials: NR
authors.lastname: Cozzarelli
mesh_terms: D004586:Electrophoresis; D008854:Microscopy, Electron; D008957:Models, Genetic; D008958:Models, Molecular; D009713:Nucleotidyltransferases / Q000378:metabolism*; D011995:Recombination, Genetic; D019895:Transposases
chemical_list: D009713:Nucleotidyltransferases; D019895:Transposases