In vivo covalent cross-linking of cellular actin by the Vibrio cholerae RTX toxin

K. J. Fullner, J. J. Mekalanos*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

131 Scopus citations


Enteric pathogens often export toxins that elicit diarrhea as a part of the etiology of disease, including toxins that affect cytoskeletal structure. Recently, we discovered that the intestinal pathogen Vibrio cholerae elicits rounding of epithelial cells that is dependent upon a gene we designated rtxA. Here we investigate the association of rtxA with the cell-rounding effect. We find that V. cholerae exports a large toxin, RTX (repeats-in-toxin) toxin, to culture supernatant fluids and that this toxin is responsible for cell rounding. Furthermore, we find that cell rounding is not due to necrosis, suggesting that RTX toxin is not a typical member of the RTX family of pore-forming toxins. Rather, RTX toxin causes depolymerization of actin stress fibers and covalent cross-linking of cellular actin into dimers, trimers and higher multimers. This RTX toxin-specific cross-linking occurs in cells previously rounded with cytochalasin D, indicating that G-actin is the toxin target. Although several models explain our observations, our simultaneous detection of actin cross-linking and depolymerization points toward a novel mechanism of action for RTX toxin, distinguishing it from all other known toxins.

Original languageEnglish (US)
Pages (from-to)5315-5323
Number of pages9
JournalEMBO Journal
Issue number20
StatePublished - Oct 16 2000


  • Actin
  • Cytochalasin D
  • RTX toxin
  • Vibrio cholerae
  • rtxA

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)


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