The long-lived nature of clostridium perfringens iota toxin in mammalian cells induces delayed apoptosis

Infect Immun. 2009 Dec;77(12):5593-601. doi: 10.1128/IAI.00710-09. Epub 2009 Oct 5.

Abstract

Mono-ADP ribosylation of actin by bacterial toxins, such as Clostridium perfringens iota or Clostridium botulinum C2 toxins, results in rapid depolymerization of actin filaments and cell rounding. Here we report that treatment of African green monkey kidney (Vero) cells with iota toxin resulted in delayed caspase-dependent death. Unmodified actin did not reappear in toxin-treated cells, and enzyme-active toxin was detectable in the cytosol for at least 24 h. C2 toxin showed comparable, long-lived effects in cells, while a C2 toxin control lacking ADP-ribosyltransferase activity did not induce cell death. To address whether the remarkable stability of the iota and C2 toxins in cytosol was crucial for inducing cell death, we treated cells with C/SpvB, the catalytic domain of Salmonella enterica SpvB. Although C/SpvB also mono-ADP ribosylates actin as do the iota and C2 toxins, cells treated with a cell-permeating C/SpvB fusion toxin became rounded but recovered and remained viable. Moreover, unmodified actin reappeared in these cells, and ADP-ribosyltransferase activity due to C/SpvB was not detectable in the cytosol after 24 h, a result most likely due to degradation of C/SpvB. Repeated application of C/SpvB prevented recovery of cells and reappearance of unmodified actin. In conclusion, a complete but transient ADP ribosylation of actin was not sufficient to trigger apoptosis, implying that long-term stability of actin-ADP-ribosylating toxins, such as iota and C2, in the cytosol is crucial for inducing delayed, caspase-dependent cell death.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADP Ribose Transferases / genetics
  • ADP Ribose Transferases / metabolism
  • ADP Ribose Transferases / toxicity*
  • Actins / metabolism
  • Animals
  • Apoptosis*
  • Bacterial Toxins / metabolism
  • Bacterial Toxins / toxicity*
  • Botulinum Toxins / metabolism
  • Botulinum Toxins / toxicity
  • Cell Shape / drug effects
  • Chlorocebus aethiops
  • Permeability / drug effects
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Recombinant Fusion Proteins / toxicity
  • Time Factors
  • Vero Cells
  • Virulence Factors / genetics
  • Virulence Factors / metabolism
  • Virulence Factors / toxicity

Substances

  • Actins
  • Bacterial Toxins
  • Recombinant Fusion Proteins
  • Virulence Factors
  • iota toxin, Clostridium perfringens
  • ADP Ribose Transferases
  • spvB protein, Salmonella enterica virulence plasmid
  • Botulinum Toxins
  • botulinum toxin type C