Autoregulation of <i>luxR:</i> the <i>Vibrio harveyi lux</i>‐operon activator functions as a repressor

Chatterjee, Jaidip; Miyamoto, Carol M.; Meighen, Edward A.

doi:10.1111/j.1365-2958.1996.tb02628.x

Cited by 60 publications

(60 citation statements)

References 26 publications

(16 reference statements)

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“…Thus, we suggest that a competition takes place between the sRNAs and luxR mRNA in the cell. luxR transcription is relatively steady (Showalter et al 1990;Chatterjee et al 1996); however, production of sRNAs increases or decreases depending on AI levels (Lenz et al 2004). Hence, the Qrr sRNAs act like a dial to tune the levels of LuxR to the needs of the community (Fig.…”

Section: Discussionmentioning

confidence: 99%

Multiple small RNAs act additively to integrate sensory information and control quorum sensing in Vibrio harveyi

Tu¹,

Bassler²

2007

Genes Dev.

231

380

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Quorum sensing is a cell-cell communication mechanism that bacteria use to collectively regulate gene expression and, at a higher level, to coordinate group behavior. In the bioluminescent marine bacterium Vibrio harveyi, sensory information from three independent quorum-sensing systems converges on the shared response regulator LuxO. When LuxO is phosphorylated, it activates the expression of a putative repressor that destabilizes the mRNA encoding the master quorum-sensing transcriptional regulator LuxR. In the closely related species Vibrio cholerae, this repressor was revealed to be the RNA chaperone Hfq together with four small regulatory RNAs (sRNAs) called Qrr1-4 (quorum regulatory RNA). Here, we identify five Qrr sRNAs that control quorum sensing in V. harveyi. Mutational analysis reveals that only four of the five Qrrs are required for destabilization of the luxR mRNA. Surprisingly, unlike in V. cholerae where the sRNAs act redundantly, in V. harveyi, the Qrr sRNAs function additively to control quorum sensing. This latter mechanism produces a gradient of LuxR that, in turn, enables differential regulation of quorum-sensing target genes. Other regulators appear to be involved in control of V. harveyi qrr expression, allowing the integration of additional sensory information into the regulation of quorum-sensing gene expression.

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Section: Discussionmentioning

confidence: 99%

Multiple small RNAs act additively to integrate sensory information and control quorum sensing in Vibrio harveyi

Tu¹,

Bassler²

2007

Genes Dev.

231

380

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“…Indeed, both of the known quorum-sensing transcription factors, LuxR and LuxO, display autorepression ( Fig. 1; Chatterjee et al 1996;Tu et al 2010). Likewise, AphA autorepresses itself in V. cholerae (Lin et al 2007).…”

Section: Apha Represses Its Own Expressionmentioning

confidence: 99%

AphA and LuxR/HapR reciprocally control quorum sensing in vibrios

Rutherford

Kessel²,

Shao³

et al. 2011

Genes Dev.

257

351

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Bacteria cycle between periods when they perform individual behaviors and periods when they perform group behaviors. These transitions are controlled by a cell-cell communication process called quorum sensing, in which extracellular signal molecules, called autoinducers (AIs), are released, accumulate, and are synchronously detected by a group of bacteria. AI detection results in community-wide changes in gene expression, enabling bacteria to collectively execute behaviors such as bioluminescence, biofilm formation, and virulence factor production. In this study, we show that the transcription factor AphA is a master regulator of quorum sensing that operates at low cell density (LCD) in Vibrio harveyi and Vibrio cholerae. In contrast, LuxR (V. harveyi)/HapR (V. cholerae) is the master regulator that operates at high cell density (HCD). At LCD, redundant small noncoding RNAs (sRNAs) activate production of AphA, and AphA and the sRNAs repress production of LuxR/HapR. Conversely, at HCD, LuxR/HapR represses aphA. This network architecture ensures maximal AphA production at LCD and maximal LuxR/HapR production at HCD. Microarray analyses reveal that 300 genes are regulated by AphA at LCD in V. harveyi, a subset of which is also controlled by LuxR. We propose that reciprocal gradients of AphA and LuxR/ HapR establish the quorum-sensing LCD and HCD gene expression patterns, respectively.

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“…LuxR represses aphA expression, and AphA represses luxR expression (47,58). Further, because AphA and LuxR are autorepressors and regulate the transcription of the Qrrs, the concentrations of LuxR and AphA in the cell are highly controlled (29,45,59). Collectively, these feedback loops ensure precise expression levels of LuxR and AphA, drive transitions between LCD and HCD, determine the effective range of autoinducer concentrations, and prevent small fluctuations in autoinducer concentration from having a large impact on gene expression (59)(60)(61)(62).…”

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confidence: 99%

Quorum Sensing Gene Regulation by LuxR/HapR Master Regulators in Vibrios

2017

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The coordination of group behaviors in bacteria is accomplished via the cell-cell signaling process called quorum sensing. Vibrios have historically been models for studying bacterial communication due to the diverse and remarkable behaviors controlled by quorum sensing in these bacteria, including bioluminescence, type III and type VI secretion, biofilm formation, and motility. Here, we discuss the Vibrio LuxR/HapR family of proteins, the master global transcription factors that direct downstream gene expression in response to changes in cell density. These proteins are structurally similar to TetR transcription factors but exhibit distinct biochemical and genetic features from TetR that determine their regulatory influence on the quorum sensing gene network. We review here the gene groups regulated by LuxR/ HapR and quorum sensing and explore the targets that are common and unique among Vibrio species.

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Autoregulation of luxR: the Vibrio harveyi lux‐operon activator functions as a repressor

Cited by 60 publications

References 26 publications

Multiple small RNAs act additively to integrate sensory information and control quorum sensing in Vibrio harveyi

Multiple small RNAs act additively to integrate sensory information and control quorum sensing in Vibrio harveyi

AphA and LuxR/HapR reciprocally control quorum sensing in vibrios

Quorum Sensing Gene Regulation by LuxR/HapR Master Regulators in Vibrios

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