Activation of cellular phospholipase A2 by Clostridium difficile toxin B

J Cell Biochem. 1993 May;52(1):116-24. doi: 10.1002/jcb.240520115.


C. difficile toxin B is a potent cytotoxin known to disrupt the microfilaments of cultured cells. We have recently shown also increased phospholipase A2 activity in cells treated with toxin B. The activity was detected as a toxin-induced, dose-dependent release of 14C-arachidonic acid from prelabeled fibroblasts. Here is shown that the toxin elicited a 14C-arachidonic acid release in a cell mutant resistant to the toxin B effect on the microfilaments. The toxin-induced release was further characterized using fibroblasts. Within 20 min high doses of toxin B (6 micrograms/ml) elicited a release which increased exponentially with time. Of the major membrane phospholipids the lipase activity affected mainly phosphatidyl ethanolamine. Neither cycloheximide nor pertussis toxin treatment or target cells inhibited the toxin-induced release, while it could be increased with 12-O-tetradecanoylphorbol-13-acetate. Our results also suggest a toxin-mediated increase in phospholipase C activity occurring at a later stage than the phospholipase A2 activation. We conclude that the ability of toxin B to induce phospholipase activation represents a hitherto unrecognized toxin B effect which is neither a cause nor a consequence of toxin-induced microfilament disorganization.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arachidonic Acid / metabolism
  • Bacterial Proteins*
  • Bacterial Toxins / pharmacology*
  • Calcium / physiology
  • Cells, Cultured
  • Clostridium difficile*
  • Cytoskeleton / drug effects*
  • Cytotoxins / pharmacology*
  • Enzyme Activation / drug effects
  • GTP-Binding Proteins / physiology
  • Humans
  • Pertussis Toxin
  • Phospholipases A / drug effects*
  • Phospholipases A2
  • Protein Biosynthesis
  • Protein Kinase C / physiology
  • Type C Phospholipases / physiology
  • Virulence Factors, Bordetella / pharmacology


  • Bacterial Proteins
  • Bacterial Toxins
  • Cytotoxins
  • Virulence Factors, Bordetella
  • toxB protein, Clostridium difficile
  • Arachidonic Acid
  • Pertussis Toxin
  • Protein Kinase C
  • Phospholipases A
  • Phospholipases A2
  • Type C Phospholipases
  • GTP-Binding Proteins
  • Calcium