Path of DNA within the Mu transpososome. Transposase interactions bridging two Mu ends and the enhancer trap five DNA supercoils

Cell. 2002 May 17;109(4):425-36. doi: 10.1016/s0092-8674(02)00728-6.


The phage Mu transpososome is assembled by interactions of transposase subunits with the left (L) and right (R) ends of Mu and an enhancer (E) located in between. A metastable three-site complex LER progresses into a more stable type 0 complex in which a tetrameric transposase is poised for DNA cleavage. "Difference topology" has revealed five trapped negative supercoils within type 0, three contributed by crossings of E with L and R, and two by crossings of L with R. This is the most complex DNA arrangement seen to date within a recombination synapse. Contrary to the prevailing notion, the enhancer appears not to be released immediately following type 0 assembly. Difference topology provides a simple method for determining the ordered sequestration of DNA segments within nucleoprotein assemblies.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Bacteriophage mu / genetics*
  • Bacteriophage mu / metabolism
  • Binding Sites / genetics
  • Biological Assay
  • DNA Transposable Elements / genetics*
  • DNA, Superhelical / genetics*
  • DNA, Superhelical / metabolism
  • DNA, Viral / genetics*
  • DNA, Viral / metabolism
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / metabolism
  • Enhancer Elements, Genetic / genetics*
  • Gene Expression Regulation, Enzymologic / genetics
  • Gene Expression Regulation, Viral / genetics
  • Integrases / genetics
  • Integrases / metabolism
  • Molecular Structure
  • Plasmids / genetics
  • Protein Structure, Tertiary / genetics
  • Recombination, Genetic / genetics
  • Transposases / genetics*
  • Viral Proteins / genetics
  • Viral Proteins / metabolism


  • DNA Transposable Elements
  • DNA, Superhelical
  • DNA, Viral
  • DNA-Binding Proteins
  • Viral Proteins
  • Cre recombinase
  • Integrases
  • Transposases