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Structural basis for the MukB-topoisomerase IV interaction and its functional implications in vivo

Seychelle M Vos1, Nichole K Stewart, Martha G Oakley

  • 1Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.

The EMBO Journal
|October 8, 2013
PubMed

Insights

The MukB protein stimulates topoisomerase IV activity in Escherichia coli, crucial for chromosome segregation. Their interaction, revealed by crystal structure, is essential for DNA disentanglement during cell division.

Area of Science:

  • Microbiology
  • Structural Biology
  • Molecular Biology

Background:

  • Chromosome partitioning in Escherichia coli relies on topoisomerase IV and MukB.
  • MukB enhances the relaxation of supercoiled DNA by topoisomerase IV.

Purpose of the Study:

  • To elucidate the mechanism of interaction between MukB and topoisomerase IV.
  • To define the functional interplay between these two proteins during chromosome segregation.

Main Methods:

  • Determined the crystal structure of a minimal MukB-topoisomerase IV complex at 2.3 Å resolution.
  • Conducted biochemical studies to analyze the interaction.
  • Utilized complementation tests with mutant proteins.

Main Results:

  • The crystal structure revealed a heterotetrameric assembly between MukB's hinge region and topoisomerase IV's ParC subunit C-terminal DNA binding domain (CTD).
  • MukB's hinge region stimulates topoisomerase IV by displacing a repressor on the CTD.
  • Cellular dependency on topoisomerase IV involves both DNA strand passage and MukB binding.

Conclusions:

  • The MukB-topoisomerase IV complex structure suggests potential for oligomeric arrays, facilitating collaborative DNA disentanglement.
  • Understanding this interaction provides insights into bacterial chromosome segregation mechanisms.

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