A negative feedback loop involving small RNAs accelerates Vibrio cholerae's transition out of quorum-sensing mode

Sine L. Svenningsen, Christopher M. Waters, Bonnie L. Bassler

Research output: Contribution to journalArticle

88 Scopus citations

Abstract

Quorum sensing is a cell-to-cell communication process that allows bacteria to measure their population numbers and to synchronously alter gene expression in response to changes in cell population density. At the core of the Vibrio cholerae quorum-sensing signal transduction pathway lie four redundant small RNAs (sRNAs), named the Quorum Regulatory RNAs (Qrr1-4). Expression of qrr1-4 is cell population density-dependent due to a requirement for the quorum-sensing controlled phosphorylated response regulator LuxO-P, which is abundant only at low cell population density. When expressed, Qrr1-4 repress translation of HapR, the "master" quorum-sensing transcription factor. Here we show a negative feedback loop in which HapR activates transcription of the qrr genes, which indirectly leads to hapR repression. Efficient feedback activation of the qrr genes requires the simultaneous presence of LuxO-P (present only at low cell population density) and HapR (present only at high cell population density). For this reason, the feedback loop does not influence quorum sensing at steady-state low or high cell population density. However, LuxO-P and HapR are simultaneously present immediately following the switch from high to low cell density conditions. In this state, the HapR feedback loop dramatically accelerates V. cholerae's transition from the high to the low cell density mode.

Original languageEnglish (US)
Pages (from-to)226-238
Number of pages13
JournalGenes and Development
Volume22
Issue number2
DOIs
StatePublished - Jan 15 2008

All Science Journal Classification (ASJC) codes

  • Genetics
  • Developmental Biology

Keywords

  • Negative feedback loop
  • Quorum sensing
  • Small RNA

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