Growth phase regulation of Vibrio cholerae RTX toxin export

Bethany Kay Boardman, Brian M. Meehan, Karla J.Fullner Satchell*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


Vibrio cholerae, the causative agent of the severe diarrheal disease cholera, secretes several "accessory" toxins, including RTX toxin, which causes the cross-linking of the actin cytoskeleton. RTX toxin is exported to the extracellular milieu by an atypical type I secretion system (T1SS), and we previously noted that RTX-associated activity is detectable only in supernatant fluids from log phase cultures. Here, we investigate the mechanisms for regelating RTX toxin activity in supernatant fluids. We find that exported proteases are capable of destroying RTX activity and may therefore play a role in the growth phase regulation of toxin activity. We determined that the absence of RTX toxin in stationary-phase culture supernatant fluids is also due to a lack of toxin secretion and not attributable to solely proteolytic degradation. We ascertained that the T1SS apparatus is regulated at the transcriptional level by growth phase control that is independent of quorum sensing, unlike other virulence factors of V. cholerae. Additionally, in stationary-phase cultures, all RTX toxin activity is associated with bacterial membranes or outer membrane vesicles.

Original languageEnglish (US)
Pages (from-to)1827-1835
Number of pages9
JournalJournal of bacteriology
Issue number5
StatePublished - Mar 2007

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


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