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Structural characterization of VapB46 antitoxin from Mycobacterium tuberculosis: insights into VapB46-DNA binding

Madhurima Roy1, Anirban Kundu1, Anirban Bhunia2

  • 1Department of Biotechnology, Indian Institute of Technology Kharagpur, India.

The FEBS Journal
|December 22, 2018
PubMed

Insights

Mycobacterium tuberculosis persister cells contribute to drug resistance. Researchers characterized the VapB46 antitoxin, revealing its DNA-binding mechanism and potential role in regulating persistence via the VapBC toxin-antitoxin system.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Structural Biology

Background:

  • Mycobacterium tuberculosis (Mtb) persister cell formation is a major driver of drug resistance.
  • Toxin-antitoxin systems are implicated in bacterial persistence, with VapBC being the largest family in Mtb.
  • Understanding VapBC systems is crucial for developing strategies against Mtb infections.

Purpose of the Study:

  • To characterize the VapB46 antitoxin structure and its DNA-binding interaction.
  • To elucidate the molecular mechanism of VapB46 in regulating Mtb persistence.

Main Methods:

  • Electrophoretic mobility shift assay (EMSA) to assess DNA binding.
  • DNase I footprinting to map DNA-binding sites.
  • Nuclear Magnetic Resonance (NMR) spectroscopy for structural determination.

Main Results:

  • VapB46 binds to two specific sites in the promoter-operator region of its cognate DNA.
  • NMR studies revealed a dimeric N-terminal domain in VapB46, containing a Phd/YefM motif essential for DNA binding.
  • Disordered C-terminal residues facilitate higher-order oligomerization.

Conclusions:

  • A DNA-binding model proposes tetrameric VapB46 binding to two promoter sites via its dimeric N-terminal domains.
  • This structural and functional characterization provides insights into VapBC system regulation and Mtb persistence.
  • Findings may inform new therapeutic approaches targeting drug-resistant tuberculosis.
Keywords:
NMR spectroscopyPhd/YefMprotein-DNA interactiontoxin-antitoxinvirulence-associated protein

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