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

Shailja Pathania1, Makkuni Jayaram, Rasika M Harshey

  • 1Section of Molecular Genetics and Microbiology and Institute of Cellular and Molecular Biology, University of Texas at Austin, 78712, USA.

Cell
|June 28, 2002
PubMed

Insights

The phage Mu transpososome

Area of Science:

  • Molecular Biology
  • Structural Biology
  • Genetics

Background:

  • The phage Mu transpososome assembly involves transposase subunits, Mu DNA ends (L and R), and an enhancer (E).
  • A metastable LER complex transitions to a stable type 0 complex, preparing for DNA cleavage.

Purpose of the Study:

  • To elucidate the complex DNA arrangement and topology within the phage Mu type 0 transpososome.
  • To investigate the role and release timing of the enhancer during transpososome assembly.

Main Methods:

  • Utilizing "difference topology" to analyze the three-dimensional structure of the type 0 complex.
  • Characterizing the interactions between transposase, Mu DNA ends, and the enhancer.

Main Results:

  • Revealed five trapped negative supercoils in the type 0 complex: three from enhancer-DNA crossings and two from DNA-DNA crossings.
  • Identified the most complex DNA arrangement to date within a recombination synapse.
  • Demonstrated that the enhancer is not immediately released after type 0 assembly.

Conclusions:

  • Difference topology offers a straightforward method for analyzing DNA segment sequestration in nucleoprotein assemblies.
  • The phage Mu type 0 complex exhibits intricate DNA supercoiling essential for transposition.
  • The enhancer plays a sustained role beyond initial type 0 complex formation.

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