TitleNegative feedback loops involving small regulatory RNAs precisely control the Vibrio harveyi quorum-sensing response.
Publication TypeJournal Article
Year of Publication2010
AuthorsTu, KC, Long, T, Svenningsen, SL, Wingreen, NS, Bassler, BL
JournalMol Cell
Date Published2010 Feb 26
KeywordsBacterial Proteins, Base Sequence, Gene Expression Regulation, Bacterial, Molecular Sequence Data, Nucleic Acid Conformation, Protein Biosynthesis, Quorum Sensing, Repressor Proteins, RNA Processing, Post-Transcriptional, RNA, Bacterial, Transcription, Genetic, Vibrio

Quorum-sensing (QS) bacteria assess population density through secretion and detection of molecules called autoinducers (AIs). We identify and characterize two Vibrio harveyi negative feedback loops that facilitate precise transitions between low-cell-density (LCD) and high-cell-density (HCD) states. The QS central regulator LuxO autorepresses its own transcription, and the Qrr small regulatory RNAs (sRNAs) posttranscriptionally repress luxO. Disrupting feedback increases the concentration of AIs required for cells to transit from LCD to HCD QS modes. Thus, the two cooperative negative feedback loops determine the point at which V. harveyi has reached a quorum and control the range of AIs over which the transition occurs. Negative feedback regulation also constrains the range of QS output by preventing sRNA levels from becoming too high and preventing luxO mRNA levels from reaching zero. We suggest that sRNA-mediated feedback regulation is a network design feature that permits fine-tuning of gene regulation and maintenance of homeostasis.

Alternate JournalMol. Cell