Inhibition of macromolecular synthesis in cultured macrophages by Pseudomonas pseudomallei exotoxin

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Published on: November 22, 2013

R Mohamed1, S Nathan, N Embi

  • 1Department of Biochemistry, Life Science Faculty, Universiti Kebangsaan Malaysia, Selangor.

Microbiology and Immunology
|January 1, 1989
PubMed

Insights

Pseudomonas pseudomallei exotoxin strongly inhibits protein and DNA synthesis in macrophages. Protein synthesis is affected at lower doses and faster than DNA synthesis, impacting host defense mechanisms.

Area of Science:

  • Microbiology
  • Cell Biology
  • Toxicology

Background:

  • Pseudomonas pseudomallei exotoxin is a virulence factor.
  • Understanding its cellular targets is crucial for elucidating its pathogenicity.

Purpose of the Study:

  • To investigate the effects of P. pseudomallei exotoxin on protein and DNA synthesis in cultured macrophages.
  • To determine the dose- and time-dependency of the exotoxin's inhibitory effects.

Main Methods:

  • Cultured macrophages were incubated with varying concentrations of P. pseudomallei exotoxin.
  • Inhibition of protein synthesis was measured by [3H]-leucine incorporation.
  • Inhibition of DNA synthesis was measured by [3H]-thymidine uptake.

Main Results:

  • P. pseudomallei exotoxin potently inhibited both protein and DNA synthesis in macrophages.
  • Protein synthesis inhibition occurred at significantly lower toxin concentrations (0.06-2.0 µg/ml) and faster than DNA synthesis inhibition.
  • Maximal protein synthesis inhibition (70%) was observed after 6 hours, while DNA synthesis was minimally affected even after 10 hours.
  • A correlation between cell damage and DNA synthesis inhibition was noted.

Conclusions:

  • P. pseudomallei exotoxin differentially affects macromolecular synthesis in macrophages, with a more pronounced and rapid effect on protein synthesis.
  • These findings suggest a mechanism by which the exotoxin may modulate the host defense response.

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