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Mycobacterium tuberculosis PPE2 Protein Interacts with p67phox and Inhibits Reactive Oxygen Species Production

Shruti Srivastava1,2, Madhu Babu Battu1, Mehak Zahoor Khan3

  • 1Laboratory of Molecular Cell Biology, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana 500039, India.

Journal of Immunology (Baltimore, Md. : 1950)
|August 4, 2019
PubMed

Insights

Mycobacterium tuberculosis PPE2 protein inhibits reactive oxygen species (ROS) production by disrupting NADPH oxidase assembly. This mechanism enhances bacterial survival within host macrophages, offering insights into tuberculosis pathogenesis.

Area of Science:

  • Immunology
  • Microbiology
  • Molecular Biology

Background:

  • Mycobacterium tuberculosis (Mtb) evades host immune defenses, particularly reactive oxygen species (ROS) generated by macrophages.
  • Understanding Mtb's survival strategies is crucial for developing effective tuberculosis (TB) therapeutics.

Purpose of the Study:

  • To investigate the role of Mtb secretory protein PPE2 in modulating macrophage oxidative stress response.
  • To elucidate the molecular mechanism by which PPE2 affects NADPH oxidase activity.

Main Methods:

  • Assessed ROS generation in macrophages (RAW 264.7 and murine peritoneal) treated with Mtb PPE2.
  • Investigated PPE2 interaction with NADPH oxidase subunits (p67phox, p47phox) using co-immunoprecipitation.
  • Utilized site-directed mutagenesis (Trp236Ala) to determine the role of specific PPE2 residues.
  • Compared survival of Mtb strains (wild-type, PPE2-null, complemented) in infected macrophages.

Main Results:

  • Mtb PPE2 significantly inhibited NADPH oxidase-mediated ROS production in macrophages.
  • PPE2 directly interacted with p67phox, preventing the translocation of p67phox and p47phox to the cell membrane.
  • A specific mutation (Trp236Ala) in PPE2 abolished its interaction with p67phox and its ROS inhibitory effect.
  • Mtb expressing PPE2 demonstrated enhanced survival in macrophages compared to PPE2-deficient mutants.

Conclusions:

  • Mtb PPE2 protein suppresses macrophage ROS production by inhibiting NADPH oxidase complex assembly.
  • This suppression of oxidative stress is vital for Mtb's intracellular survival.
  • PPE2 represents a potential therapeutic target for combating tuberculosis.

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