Interaction of Proteins Located at a Distance Along DNA: Mechanism of Target Immunity in the Mu DNA Strand-Transfer Reaction

Cell. 1989 Apr 7;57(1):41-7. doi: 10.1016/0092-8674(89)90170-0.


DNA molecules carrying a Mu end(s) are inefficient targets in the Mu DNA strand-transfer reaction. This target immunity is due to preferential dissociation of Mu B protein from DNA molecules that have Mu A protein bound to the Mu end; free DNA is a much poorer target than DNA with Mu B protein bound. We show that Mu B protein, which binds nonspecifically to DNA, is immobile once bound. An encounter between Mu A and Mu B proteins, bound some distance apart along DNA, is necessary to facilitate the Mu B dissociation. Experiments which show that DNA without a Mu end can acquire immunity, by catenation to DNA with a Mu end(s), are consistent with a model of Mu A-Mu B interaction by DNA looping, but not by linear movement of protein(s) along DNA.

MeSH terms

  • Chromosome Mapping
  • DNA Transposable Elements
  • DNA, Bacterial / genetics*
  • DNA, Bacterial / physiology
  • DNA-Binding Proteins / metabolism*
  • Escherichia coli / genetics*
  • Immunity
  • Nucleotidyltransferases / metabolism*
  • Transposases
  • Viral Proteins*


  • DNA Transposable Elements
  • DNA, Bacterial
  • DNA-Binding Proteins
  • Mu B protein, bacteriophage
  • Viral Proteins
  • Nucleotidyltransferases
  • Transposases