The actin cross-linking domain of the Vibrio cholerae RTX toxin directly catalyzes the covalent cross-linking of actin

Christina L. Cordero, Dmitry S. Kudryashov, Emil Reisler, Karla J. Fullner Satchell*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

66 Scopus citations

Abstract

Vibrio cholerae is a Gram-negative bacterial pathogen that exports enterotoxins to alter host cells and to elicit diarrheal disease. Among the secreted toxins is the multifunctional RTX toxin, which causes cell rounding and actin depolymerization by covalently cross-linking actin monomers into dimers, trimers, and higher multimers. The region of the toxin responsible for cross-linking activity is the actin cross-linking domain (ACD). In this study, we further investigated the role of the ACD in the actin cross-linking reaction. We show that the RTX toxin cross-links actin independently of tissue transglutaminase, thus eliminating an indirect model of ACD activity. We demonstrate that a fusion protein of the ACD and the N-terminal portion of lethal factor from Bacillus anthracis (LFNACD) has cross-linking activity in vivo and in crude cell extracts. Furthermore, we determined that LFNACD directly catalyzes the formation of covalent linkages between actin molecules in vitro and that Mg2+ and ATP are essential cofactors for the cross-linking reaction. In addition, G-actin is proposed as a cytoskeletal substrate of the RTX toxin in vivo. Future studies of the in vitro cross-linking reaction will facilitate characterization of the enzymatic properties of the ACD and contribute to our knowledge of the novel mechanism of covalent actin cross-linking.

Original languageEnglish (US)
Pages (from-to)32366-32374
Number of pages9
JournalJournal of Biological Chemistry
Volume281
Issue number43
DOIs
StatePublished - Oct 27 2006

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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