Pulling Apart Catalytically Active Tn5 Synaptic Complexes Using Magnetic Tweezers

Christian D. Adams, Bernhard Schnurr, John F. Marko, William S. Reznikoff*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


The Tn5 transposase is an example of a class of proteins that move DNA sequences (transposons) via a process called transposition. DNA transposition is a widespread genetic mobility mechanism that has profoundly affected the genomes of nearly all organisms. We have used single-DNA micromanipulation experiments to study the process by which Tn5 DNA transposons are identified and processed by their transposase protein. We have determined that the energy barrier to disassemble catalytically active synaptic complexes is 16 kcal mol-1. However, we have found that the looping organization of DNA segments by transposase is less sequence-driven than previously thought. Loops anchored at some non-transposon end sequences display a disassembly energy barrier of 14 kcal mol-1, nearly as stable as the synapses formed at known transposon end sequences. However, these non-transposon end sequence independent complexes do not mediate DNA cleavage. Therefore, the sequence-sensitivity for DNA binding and looping by Tn5 transposase is significantly less than that required for DNA cleavage. These results have implications for the in vivo down regulation of transposition and the cis-transposition bias of transposase.

Original languageEnglish (US)
Pages (from-to)319-327
Number of pages9
JournalJournal of Molecular Biology
Issue number2
StatePublished - Mar 23 2007


  • Tn5
  • protein-nucleic acid interactions
  • single molecule
  • transposase
  • transposition

ASJC Scopus subject areas

  • Molecular Biology
  • Biophysics
  • Structural Biology


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