scholarly journals The VarS/VarA two-component system modulates the activity of the Vibrio cholerae quorum-sensing transcriptional regulator HapR

Microbiology ◽  
2011 ◽  
Vol 157 (6) ◽  
pp. 1620-1628 ◽  
Author(s):  
Amy M. Tsou ◽  
Zhi Liu ◽  
Tao Cai ◽  
Jun Zhu
Keyword(s):  
Quorum Sensing ◽  
Vibrio Cholerae ◽  
Cell Density ◽  
Transcriptional Regulator ◽  
Nutrient Status ◽  
Two Component System ◽  
Protein Activity ◽  
Component System ◽  
Its Gene ◽  
Two Component

The human pathogen Vibrio cholerae uses quorum sensing to regulate the expression of a number of phenotypes, including virulence factor production, in response to changes in cell density. It produces small molecules called autoinducers that increase in concentration as cell density increases, and these autoinducers bind to membrane sensors once they reach a certain threshold. This binding leads to signalling through a downstream phosphorelay pathway to alter the expression of the transcriptional regulator HapR. Previously, it was shown that the VarS/VarA two-component system acts on a component of the phosphorelay pathway upstream of HapR to regulate HapR expression levels. Here, we show that in addition to this mechanism of regulation, VarS and VarA also indirectly modulate HapR protein activity. This modulation is mediated by the small RNA CsrB but is independent of the known quorum-sensing system that links the autoinducers to HapR. Thus, the VarS/VarA two-component system intersects with the quorum-sensing network at two levels. In both cases, the effect of VarS and VarA on quorum sensing is dependent on the Csr small RNAs, which regulate carbon metabolism, suggesting that V. cholerae may integrate nutrient status and cell density sensory inputs to tailor its gene expression profile more precisely to surrounding conditions.

scholarly journals A novel two-component system modulates quorum sensing and pathogenicity inBurkholderia cenocepacia

2018 ◽  
Vol 108 (1) ◽  
pp. 32-44 ◽  
Author(s):  
Chaoyu Cui ◽  
Chunxi Yang ◽  
Shihao Song ◽  
Shuna Fu ◽  
Xiuyun Sun ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Two Component System ◽  
Component System ◽  
Two Component

scholarly journals Reciprocal Regulation of Resistance-Nodulation-Division Efflux Systems and the Cpx Two-Component System in Vibrio cholerae

2014 ◽  
Vol 82 (7) ◽  
pp. 2980-2991 ◽  
Author(s):  
Dawn L. Taylor ◽  
X. Renee Bina ◽  
Leyla Slamti ◽  
Matthew K. Waldor ◽  
James E. Bina
Keyword(s):  
Antimicrobial Resistance ◽  
Vibrio Cholerae ◽  
Cell Envelope ◽  
Two Component System ◽  
Reciprocal Regulation ◽  
Component System ◽  
Content Type ◽  
Expression Of Genes ◽  
Two Component ◽  
Resistance Nodulation Division

ABSTRACTThe Cpx two-component regulatory system has been shown inEscherichia colito alleviate stress caused by misfolded cell envelope proteins. TheVibrio choleraeCpx system was previously found to respond to cues distinct from those in theE. colisystem, suggesting that this system fulfills a different physiological role in the cholera pathogen. Here, we used microarrays to identify genes that were regulated by theV. choleraeCpx system. Our observations suggest that the activation of theV. choleraeCpx system does not induce expression of genes involved in the mitigation of stress generated by misfolded cell envelope proteins but promotes expression of genes involved in antimicrobial resistance. In particular, activation of the Cpx system induced expression of the genes encoding the VexAB and VexGH resistance-nodulation-division (RND) efflux systems and their cognate outer membrane pore protein TolC. The promoters for these loci contained putative CpxR consensus binding sites, and ectopiccpxRexpression activated transcription from the promoters for the RND efflux systems. CpxR was not required for intrinsic antimicrobial resistance, but CpxR activation enhanced resistance to antimicrobial substrates of VexAB and VexGH. Mutations that inactivated VexAB or VexGH efflux activity resulted in the activation of the Cpx response, suggesting thatvexABandvexGHand thecpxP-cpxRAsystem are reciprocally regulated. We speculate that the reciprocal regulation of theV. choleraeRND efflux systems and the Cpx two-component system is mediated by the intracellular accumulation of an endogenously produced metabolic by-product that is normally extruded from the cell by the RND efflux systems.

scholarly journals GacA, the Response Regulator of a Two-Component System, Acts as a Master Regulator in Pseudomonas syringae pv. tomato DC3000 by Controlling Regulatory RNA, Transcriptional Activators, and Alternate Sigma Factors

2003 ◽  
Vol 16 (12) ◽  
pp. 1106-1117 ◽  
Author(s):  
Asita Chatterjee ◽  
Yaya Cui ◽  
Hailian Yang ◽  
Alan Collmer ◽  
James R. Alfano ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Stress Responses ◽  
Response Regulator ◽  
Sigma Factors ◽  
Regulatory Rna ◽  
Two Component System ◽  
Tomato Dc3000 ◽  
Component System ◽  
Regulatory Cascade ◽  
Two Component

Concerted investigations of factors affecting host-pathogen interactions are now possible with the model plant Arabidopsis thaliana and its model pathogen Pseudomo-nas syringae pv. tomato DC3000, as their whole genome sequences have become available. As a prelude to analysis of the regulatory genes and their targets, we have focused on GacA, the response regulator of a two-component system. The DC3000 gene was cloned by testing for the reversal of phenotypes of an Erwinia GacA− mutant. A GacA− mutant of DC3000 constructed by marker exchange produces much-reduced levels of transcripts of three alternate sigma factors: HrpL, required for the production of effector proteins and their translocation via the type III secretion system; RpoS, required for stress responses and secondary metabolite production; and RpoN, required for an assortment of metabolic processes and expression of hrpL. GacA deficiency also reduces the expression of hrpR and hrpS, which specify enhancer-binding proteins of the NtrC family required for hrpL transcription; ahlI and ahlR, the genes for quorum sensing signal; salA, a regulatory gene known to control virulence; CorS, a sensor kinase; CorR, the cognate response regulator that controls coronatine biosynthetic genes; and rsmB and rsmZ, which specify untranslatable regulatory RNA species. gacA expression itself is regulated by environmental conditions in DC3000, since transcript levels are affected by growth phase and media composition. The observations that high levels of gacA RNA occur in the hrp-inducing medium and GacA deficiency reduces the levels of rpoS expression implicate an important role of GacA in stress responses of DC3000. Consistent with the effects on hrpL expression, the GacA− mutant produces lower levels of transcripts of avr, hrp, and hop genes controlled by HrpL. In addition, GacA deficiency results in reduced levels of transcripts of several HrpL-independent genes. As would be expected, these effects on gene expression cause drastic changes in bacterial behavior: virulence towards A. thaliana and tomato; multiplication in planta; efficiency of the induction of the hypersensitive reaction (HR); production of pigment and N-acyl-homoserine lactone (AHL), the presumed quorum-sensing signal; and swarming motility. Our findings establish that GacA, located at the top in a regulatory cascade in DC3000, functions as a central regulator by controlling an assortment of transcriptional and posttranscriptional factors.

How the PhoP/PhoQ System Controls Virulence and Mg 2+ Homeostasis: Lessons in Signal Transduction, Pathogenesis, Physiology, and Evolution

2021 ◽  
Author(s):  
Eduardo A. Groisman ◽  
Alexandre Duprey ◽  
Jeongjoon Choi
Keyword(s):  
Antimicrobial Agents ◽  
Bacterial Species ◽  
Transcriptional Regulator ◽  
Acidic Ph ◽  
Two Component System ◽  
Component System ◽  
Gram Negative ◽  
Content Type ◽  
Two Component ◽  
Serovar Typhimurium

The PhoP/PhoQ two-component system governs virulence, Mg 2+ homeostasis, and resistance to a variety of antimicrobial agents, including acidic pH and cationic antimicrobial peptides, in several Gram-negative bacterial species. Best understood in Salmonella enterica serovar Typhimurium, the PhoP/PhoQ system consists of the sensor PhoQ and the transcriptional regulator PhoP.

scholarly journals A novel two-component system BqsS-BqsR modulates quorum sensing-dependent biofilm decay inPseudomonas aeruginosa

2008 ◽  
Vol 1 (1) ◽  
pp. 88-96 ◽  
Author(s):  
Yihu Dong ◽  
Xi-Fen Zhang ◽  
Shu-Wen An ◽  
Jin-Ling Xu ◽  
Lian-Hui Zhang
Keyword(s):  
Quorum Sensing ◽  
Two Component System ◽  
Component System ◽  
Two Component

scholarly journals Diffusible Signal Factor-Mediated Quorum Sensing Plays a Central Role in Coordinating Gene Expression of Xanthomonas citri subsp. citri

2012 ◽  
Vol 25 (2) ◽  
pp. 165-179 ◽  
Author(s):  
Yinping Guo ◽  
Yanping Zhang ◽  
Jian-Liang Li ◽  
Nian Wang
Keyword(s):  
Quorum Sensing ◽  
Wild Type Strain ◽  
Xanthomonas Citri ◽  
Two Component System ◽  
Signal Molecule ◽  
Component System ◽  
Signal Perception ◽  
Two Component ◽  
Diffusible Signal Factor ◽  
Unique Genes

Diffusible signal factor (DSF) family signal-mediated quorum sensing (QS) has been identified in many gram-negative bacteria. This QS pathway of Xanthomonas spp. consists of three major QS components: RpfF, RpfC, and RpfG. The rpfF gene encodes a putative enoyl-CoA hydratase that catalyzes the synthesis of the signal molecule. RpfC and RpfG serve as a two-component system for the perception and transduction of the extracellular DSF family signals. In order to further characterize the QS regulatory network in Xanthomonas citri subsp. citri, we investigated the RpfF, RpfC, and RpfG regulons by using transcriptome analyses. Comparison of the transcriptomes of the QS mutants (rpfF, rpfC, and rpfG) with that of the wild-type strain revealed a core group of genes controlled by all three QS components, suggesting that the RpfC-RpfG two-component system is a major and conserved signal perception and transduction system for DSF family signal-mediated QS in X. citri subsp. citri. The unique genes controlled by RpfF alone indicate the complexity of the QS pathway and the involvement of additional sensory mechanisms in X. citri subsp. citri. The unique genes controlled by RpfC and RpfG, respectively, support the possibility that RpfC and RpfG play broader roles in gene regulation other than transduction of DSF signals.

scholarly journals BglJ-RcsB Heterodimers Relieve Repression of the Escherichia coli bgl Operon by H-NS

2010 ◽  
Vol 192 (24) ◽  
pp. 6456-6464 ◽  
Author(s):  
G. Raja Venkatesh ◽  
Frant Carlot Kembou Koungni ◽  
Andreas Paukner ◽  
Thomas Stratmann ◽  
Birgit Blissenbach ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Response Regulator ◽  
Consensus Sequence ◽  
Regulatory Region ◽  
Constitutive Expression ◽  
Transcriptional Regulator ◽  
Sequence Motif ◽  
Two Component System ◽  
Component System ◽  
Two Component

ABSTRACT RcsB is the response regulator of the complex Rcs two-component system, which senses perturbations in the outer membrane and peptidoglycan layer. BglJ is a transcriptional regulator whose constitutive expression causes activation of the H-NS- and StpA-repressed bgl (aryl-β,d-glucoside) operon in Escherichia coli. RcsB and BglJ both belong to the LuxR-type family of transcriptional regulators with a characteristic C-terminal DNA-binding domain. Here, we show that BglJ and RcsB interact and form heterodimers that presumably bind upstream of the bgl promoter, as suggested by mutation of a sequence motif related to the consensus sequence for RcsA-RcsB heterodimers. Heterodimerization of BglJ-RcsB and relief of H-NS-mediated repression of bgl by BglJ-RcsB are apparently independent of RcsB phosphorylation. In addition, we show that LeuO, a pleiotropic LysR-type transcriptional regulator, likewise binds to the bgl upstream regulatory region and relieves repression of bgl independently of BglJ-RcsB. Thus, LeuO can affect bgl directly, as shown here, and indirectly by activating the H-NS-repressed yjjQ-bglJ operon, as shown previously. Taken together, heterodimer formation of RcsB and BglJ expands the role of the Rcs two-component system and the network of regulators affecting the bgl promoter.

scholarly journals RegA, the Regulator of the Two-Component System RegB/RegA of Brucella suis, Is a Controller of Both Oxidative Respiration and Denitrification Required for Chronic Infection in Mice

2013 ◽  
Vol 81 (6) ◽  
pp. 2053-2061 ◽  
Author(s):  
Elias Abdou ◽  
Amélie Deredjian ◽  
María Pilar Jiménez de Bagüés ◽  
Stephan Köhler ◽  
Véronique Jubier-Maurin
Keyword(s):  
Oxygen Deficiency ◽  
Transcriptional Regulator ◽  
Two Component System ◽  
Component System ◽  
Content Type ◽  
Ubiquinol Oxidase ◽  
Two Component ◽  
Brucella Suis ◽  
Oxidative Respiration

ABSTRACTAdaptation to oxygen deficiency is essential for virulence and persistence ofBrucellainside the host. The flexibility of this bacterium with respect to oxygen depletion is remarkable, sinceBrucella suiscan use an oxygen-dependent transcriptional regulator of the FnrN family, two high-oxygen-affinity terminal oxidases, and a complete denitrification pathway to resist various conditions of oxygen deficiency. Moreover, our previous results suggested that oxidative respiration and denitrification can be simultaneously used byB. suisunder microaerobiosis. The requirement of a functional cytochromebdubiquinol oxidase for nitrite reductase expression evidenced the linkage of these two pathways, and the central role of the two-component system RegB/RegA in the coordinated control of both respiratory systems was demonstrated. We propose a scheme for global regulation ofB. suisrespiratory pathways by the transcriptional regulator RegA, which postulates a role for the cytochromebdubiquinol oxidase in redox signal transmission to the histidine sensor kinase RegB. More importantly, RegA was found to be essential forB. suispersistencein vivowithin oxygen-limited target organs. It is conceivable that RegA acts as a controller of numerous systems involved in the establishment of the persistent state, characteristic of chronic infections byBrucella.

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