Characterization of the enzymatic activity of the actin cross-linking domain from the Vibrio cholerae MARTXVc toxin

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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


Vibrio cholerae is a Gram-negative bacterial pathogen that exports enterotoxins, which alter host cells through a number of mechanisms resulting in diarrheal disease. Among the secreted toxins is the multifunctional, autoprocessing RTX toxin (MARTXVc), which disrupts actin cytoskeleton by covalently cross-linking actin monomers into oligomers. The region of the toxin responsible for cross-linking activity is the actin cross-linking domain (ACD). In this study, we demonstrate unambiguously that ACD utilizes G- and not F-actin as a substrate for the cross-linking reaction and hydrolyzes one molecule of ATP per cross-linking event. Furthermore, major actin-binding proteins that regulate actin cytoskeleton in vivo do not block the cross-linking reaction in vitro. Cofilin inhibits the cross-linking of G- and F-actin, at a high mole ratio to actin but accelerates F-actin cross-linking at low mole ratios. DNase I completely blocks the cross-linking of actin, likely due to steric hindrance with one of the cross-linking sites on actin. In the context of the holotoxin, the inhibition of Rho by the Rho-inactivating domain of MARTXVc (Sheahan, K. L., and Satchell, K. J. F. (2007) Cell. Microbiol. 9, 1324-1335) would accelerate F-actin depolymerization and provide G-actin, alone or in complex with actin-binding proteins, for cross-linking by ACD, ultimately leading to the observed rapid cell rounding.

Original languageEnglish (US)
Pages (from-to)445-452
Number of pages8
JournalJournal of Biological Chemistry
Issue number1
StatePublished - Jan 4 2008

ASJC Scopus subject areas

  • Molecular Biology
  • Biochemistry
  • Cell Biology


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