Clostridium difficile toxin CDT induces formation of microtubule-based protrusions and increases adherence of bacteria

PLoS Pathog. 2009 Oct;5(10):e1000626. doi: 10.1371/journal.ppat.1000626. Epub 2009 Oct 16.


Clostridium difficile causes antibiotic-associated diarrhea and pseudomembranous colitis by production of the Rho GTPase-glucosylating toxins A and B. Recently emerging hypervirulent Clostridium difficile strains additionally produce the binary ADP-ribosyltransferase toxin CDT (Clostridium difficile transferase), which ADP-ribosylates actin and inhibits actin polymerization. Thus far, the role of CDT as a virulence factor is not understood. Here we report by using time-lapse- and immunofluorescence microscopy that CDT and other binary actin-ADP-ribosylating toxins, including Clostridium botulinum C2 toxin and Clostridium perfringens iota toxin, induce redistribution of microtubules and formation of long (up to >150 microm) microtubule-based protrusions at the surface of intestinal epithelial cells. The toxins increase the length of decoration of microtubule plus-ends by EB1/3, CLIP-170 and CLIP-115 proteins and cause redistribution of the capture proteins CLASP2 and ACF7 from microtubules at the cell cortex into the cell interior. The CDT-induced microtubule protrusions form a dense meshwork at the cell surface, which wrap and embed bacterial cells, thereby largely increasing the adherence of Clostridia. The study describes a novel type of microtubule structure caused by less efficient microtubule capture and offers a new perspective for the pathogenetic role of CDT and other binary actin-ADP-ribosylating toxins in host-pathogen interactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADP Ribose Transferases / metabolism
  • ADP Ribose Transferases / pharmacology*
  • ADP Ribose Transferases / physiology
  • Actin Cytoskeleton / drug effects
  • Actin Cytoskeleton / metabolism
  • Animals
  • Bacterial Adhesion / drug effects*
  • Bacterial Adhesion / physiology
  • Bacterial Toxins / metabolism
  • Bacterial Toxins / pharmacology*
  • Caco-2 Cells
  • Cell Surface Extensions / drug effects*
  • Cell Surface Extensions / metabolism
  • Clostridium difficile* / enzymology
  • Clostridium difficile* / physiology
  • Dose-Response Relationship, Drug
  • Germ-Free Life
  • HT29 Cells
  • Humans
  • Mice
  • Microtubules / drug effects*
  • Microtubules / metabolism
  • Rats
  • Rats, Wistar


  • Bacterial Toxins
  • ADP Ribose Transferases