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Protein synthesis is required for expression of anthrax lethal toxin cytotoxicity

R Bhatnagar1, A M Friedlander

  • 1United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland 21702-5011.

Infection and Immunity
|July 1, 1994
PubMed

Insights

Anthrax lethal toxin causes cell death, but continuous protein synthesis is required for its activity. Blocking protein synthesis protects cells from lethal toxin-induced cytolysis, revealing a key mechanism in anthrax pathogenesis.

Area of Science:

  • Cell Biology
  • Toxicology
  • Immunology

Background:

  • Anthrax lethal toxin (LT) comprises protective antigen (PA) and lethal factor (LF).
  • LT induces cytolysis in macrophages and macrophage-like cell lines.
  • The precise mechanism of LT-induced cell death remains under investigation.

Purpose of the Study:

  • To investigate the role of protein synthesis in anthrax lethal toxin-induced cytolysis.
  • To determine at which stage of intoxication protein synthesis is essential for LT activity.
  • To elucidate the mechanism of cell death mediated by anthrax lethal toxin.

Main Methods:

  • Utilized J774A.1 macrophage cell line and anthrax lethal toxin.
  • Inhibited protein synthesis using cycloheximide and puromycin.
  • Assessed cell viability, protective antigen binding, toxin uptake, and calcium influx.

Main Results:

  • Inhibition of protein synthesis protected J774A.1 cells from LT-induced cytolysis.
  • Protein synthesis is required for the expression of lethal toxin activity, not for initial binding or uptake.
  • Blocking protein synthesis prevented the increased calcium uptake observed in LT-exposed cells.
  • Protection was effective even when protein synthesis was inhibited up to 1 hour post-toxin exposure.

Conclusions:

  • Continuous protein synthesis is essential for anthrax lethal toxin activity and subsequent cell death.
  • Protein synthesis is required at a later stage of the intoxication process.
  • Understanding the proteins synthesized during intoxication may clarify the mechanism of LT-induced cell death.

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