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The MukB-topoisomerase IV interaction is required for proper chromosome compaction

Rupesh Kumar1, Pearl Nurse1, Soon Bahng1

  • 1From the Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065.

The Journal of Biological Chemistry
|August 27, 2017
PubMed

Insights

The bacterial condensin MukB protein interacts with topoisomerase IV, enhancing DNA condensation and loop stabilization. This interaction is crucial for proper chromosome segregation, as mutations impairing it cause severe DNA decompaction.

Area of Science:

  • Bacterial cell biology
  • Molecular genetics
  • DNA topology

Background:

  • The bacterial condensin MukB protein plays a key role in DNA condensation.
  • Topoisomerase IV is an enzyme responsible for decatenating linked DNA molecules.

Purpose of the Study:

  • To investigate the functional consequences of the interaction between MukB and topoisomerase IV.
  • To elucidate the role of this complex in DNA condensation and chromosome segregation.

Main Methods:

  • Biochemical assays to study DNA relaxation and knotting.
  • Analysis of DNA condensation in bacterial cells with varying MukB and topoisomerase IV interactions.
  • Genetic analysis of *mukB* mutant alleles.

Main Results:

  • The interaction between MukB and topoisomerase IV enhances MukB-mediated DNA condensation without increasing MukB binding.
  • This stabilization effect does not depend on topoisomerase IV's catalytic activity.
  • Mutations preventing MukB-topoisomerase IV interaction lead to severe nucleoid decompaction and chromosome segregation defects.

Conclusions:

  • The MukB-topoisomerase IV complex acts as a scaffold, promoting extensive DNA condensation.
  • This complex is essential for maintaining genome integrity and ensuring proper chromosome segregation in bacteria.
Keywords:
DNADNA structureDNA topoisomeraseDNA topologynucleic acid enzymology

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