The Complex Rcs Regulatory Cascade

2018 ◽  
Vol 72 (1) ◽  
pp. 111-139 ◽  
Author(s):  
Erin Wall ◽  
Nadim Majdalani ◽  
Susan Gottesman
Keyword(s):  
Response Regulator ◽  
Two Component System ◽  
Regulatory Cascade ◽  
Outer Membrane Lipoprotein ◽  
Two Component ◽  
Membrane Lipoprotein ◽  
Inner Membrane Protein ◽  
Insight Into ◽  
System Paradigm

RcsB, a response regulator of the FixJ/NarL family, is at the center of a complex network of regulatory inputs and outputs. Cell surface stress is sensed by an outer membrane lipoprotein, RcsF, which regulates interactions of the inner membrane protein IgaA, lifting negative regulation of a phosphorelay. In vivo evidence supports a pathway in which histidine kinase RcsC transfers phosphate to phosphotransfer protein RcsD, resulting in phosphorylation of RcsB. RcsB acts either alone or in combination with RcsA to positively regulate capsule synthesis and synthesis of small RNA (sRNA) RprA as well as other genes, and to negatively regulate motility. RcsB in combination with other FixJ/NarL auxiliary proteins regulates yet other functions, independent of RcsB phosphorylation. Proper expression of Rcs and its targets is critical for success of Escherichia coli commensal strains, for proper development of biofilm, and for virulence in some pathogens. New understanding of how the Rcs phosphorelay works provides insight into the flexibility of the two-component system paradigm.

scholarly journals Identification of a novel two-component system SenS/SenR modulating the production of the catalase-peroxidase CpeB and the haem-binding protein HbpS in Streptomyces reticuli

Microbiology ◽  
2005 ◽  
Vol 151 (11) ◽  
pp. 3603-3614 ◽  
Author(s):  
Darío Ortiz de Orué Lucana ◽  
Peijian Zou ◽  
Marc Nierhaus ◽  
Hildgund Schrempf
Keyword(s):  
Peroxidase Activity ◽  
Response Regulator ◽  
Binding Protein ◽  
Streptomyces Avermitilis ◽  
Binding Motif ◽  
Two Component System ◽  
Component System ◽  
Regulatory Cascade ◽  
Two Component

The Gram-positive soil bacterium and cellulose degrader Streptomyces reticuli synthesizes the mycelium-associated enzyme CpeB, which displays haem-dependent catalase and peroxidase activity, as well as haem-independent manganese-peroxidase activity. The expression of the furS–cpeB operon depends on the redox regulator FurS and the presence of the haem-binding protein HbpS. Upstream of hbpS, the neighbouring senS and senR genes were identified. SenS is a sensor histidine kinase with five predicted N-terminally located transmembrane domains. SenR is the corresponding response regulator with a C-terminal DNA-binding motif. Comparative transcriptional and biochemical studies with a designed S. reticuli senS/senR chromosomal disruption mutant and a set of constructed Streptomyces lividans transformants showed that the presence of the novel two-component system SenS/SenR negatively modulates the expression of the furS–cpeB operon and the hbpS gene. The presence of SenS/SenR enhances considerably the resistance of S. reticuli to haemin and the redox-cycling compound plumbagin, suggesting that this system could participate directly or indirectly in the sensing of redox changes. Epitope-tagged HbpS (obtained from an Escherichia coli transformant) as well as the native S. reticuli HbpS interact in vitro specifically with the purified SenS fusion protein. On the basis of these findings, together with data deduced from the S. reticuli hbpS mutant strain, HbpS is suggested to act as an accessory protein that communicates with the sensor protein to modulate the corresponding regulatory cascade. Interestingly, close and distant homologues, respectively, of the SenS/SenR system are encoded within the Streptomyces coelicolor A3(2) and Streptomyces avermitilis genomes, but not within other known bacterial genomes. Hence the SenS/SenR system appears to be confined to streptomycetes.

scholarly journals Quantitative Kinetic Analyses of Shutting Off a Two-Component System

mBio ◽  
2017 ◽  
Vol 8 (3) ◽  
Author(s):  
Rong Gao ◽  
Ann M. Stock
Keyword(s):  
Phosphatase Activity ◽  
Response Regulator ◽  
Two Component System ◽  
Component System ◽  
Signaling Systems ◽  
Cellular Environment ◽  
Two Component ◽  
The Impact

ABSTRACT Cells rely on accurate control of signaling systems to adapt to environmental perturbations. System deactivation upon stimulus removal is as important as activation of signaling pathways. The two-component system (TCS) is one of the major bacterial signaling schemes. In many TCSs, phosphatase activity of the histidine kinase (HK) is believed to play an essential role in shutting off the pathway and resetting the system to the prestimulus state. Two basic challenges are to understand the dynamic behavior of system deactivation and to quantitatively evaluate the role of phosphatase activity under natural cellular conditions. Here we report a kinetic analysis of the response to shutting off the archetype Escherichia coli PhoR-PhoB TCS pathway using both transcription reporter assays and in vivo phosphorylation analyses. Upon removal of the stimulus, the pathway is shut off by rapid dephosphorylation of the PhoB response regulator (RR) while PhoB-regulated gene products gradually reset to prestimulus levels through growth dilution. We developed an approach combining experimentation and modeling to assess in vivo kinetic parameters of the phosphatase activity with kinetic data from multiple phosphatase-diminished mutants. This enabled an estimation of the PhoR phosphatase activity in vivo , which is much stronger than the phosphatase activity of PhoR cytoplasmic domains analyzed in vitro . We quantitatively modeled how strong the phosphatase activity needs to be to suppress nonspecific phosphorylation in TCSs and discovered that strong phosphatase activity of PhoR is required for cross-phosphorylation suppression. IMPORTANCE Activation of TCSs has been extensively studied; however, the kinetics of shutting off TCS pathways is not well characterized. We present comprehensive analyses of the shutoff response for the PhoR-PhoB system that reveal the impact of phosphatase activity on shutoff kinetics. This allows development of a quantitative framework not only to characterize the phosphatase activity in the natural cellular environment but also to understand the requirement for specific strengths of phosphatase activity to suppress nonspecific phosphorylation. Our model suggests that the ratio of the phosphatase rate to the nonspecific phosphorylation rate correlates with TCS expression levels and the ratio of the RR to HK, which may contribute to the great diversity of enzyme levels and activities observed in different TCSs.

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.

scholarly journals Constitutive Activation of Two-Component Response Regulators: Characterization of VirG Activation in Agrobacterium tumefaciens

2006 ◽  
Vol 188 (14) ◽  
pp. 5204-5211 ◽  
Author(s):  
Rong Gao ◽  
Aindrila Mukhopadhyay ◽  
Fang Fang ◽  
David G. Lynn
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Conformational Changes ◽  
Response Regulator ◽  
Structural Features ◽  
Response Regulators ◽  
Two Component System ◽  
Plant Host ◽  
Two Component ◽  
Two Component Signal Transduction

ABSTRACT Response regulators are the ultimate modulators in two-component signal transduction pathways. The N-terminal receiver domains generally accept phosphates from cognate histidine kinases to control output. VirG for example, the response regulator of the VirA/VirG two-component system in Agrobacterium tumefaciens, mediates the expression of virulence genes in response to plant host signals. Response regulators have a highly conserved structure and share a similar conformational activation upon phosphorylation, yet the sequence and structural features that determine or perturb the cooperative activation events are ill defined. Here we use VirG and the unique features of the Agrobacterium system to extend our understanding of the response regulator activation. Two previously isolated constitutive VirG mutants, VirGN54D and VirGI77V/D52E, provide the foundation for our studies. In vivo phosphorylation patterns establish that VirGN54D is able to accumulate phosphates from small-molecule phosphate donors, such as acetyl phosphate, while the VirGI77V/D52E allele carries conformational changes mimicking the active conformation. Further structural alterations on these two alleles begin to reveal the changes necessary for response regulator activation.

scholarly journals Requirement of the Receiver and Phosphotransfer Domains of ArcB for Efficient Dephosphorylation of Phosphorylated ArcA In Vivo

2005 ◽  
Vol 187 (9) ◽  
pp. 3267-3272 ◽  
Author(s):  
Gabriela R. Peña-Sandoval ◽  
Ohsuk Kwon ◽  
Dimitris Georgellis
Keyword(s):  
Response Regulator ◽  
Growth Conditions ◽  
Sensor Kinase ◽  
Aerobic Growth ◽  
Two Component System ◽  
Two Component ◽  
Necessary And Sufficient ◽  
Respiratory Conditions

ABSTRACT The Arc two-component system, comprising the ArcB sensor kinase and the ArcA response regulator, modulates the expression of numerous genes in response to the respiratory conditions of growth. Under anoxic growth conditions, ArcB autophosphorylates and transphosphorylates ArcA, which in turn represses or activates its target operons. Under aerobic growth conditions, phosphorylated ArcA (ArcA-P) dephosphorylates and its transcriptional regulation is released. The dephosphorylation of ArcA-P has been shown to occur, at least in vitro, via an ArcAAsp54-P → ArcBHis717-P → ArcBAsp576-P → Pi reverse phosphorelay. In this study, the physiological significance of this pathway was assessed. The results demonstrate that the receiver and phosphotransfer domains of the tripartite sensor kinase ArcB are necessary and sufficient for efficient ArcA-P dephosphorylation in vivo.

scholarly journals Effect of d-Lactate on the Physiological Activity of the ArcB Sensor Kinase in Escherichia coli

2004 ◽  
Vol 186 (7) ◽  
pp. 2085-2090 ◽  
Author(s):  
Claudia Rodriguez ◽  
Ohsuk Kwon ◽  
Dimitris Georgellis
Keyword(s):  
Kinase Activity ◽  
Response Regulator ◽  
Physiological Activity ◽  
Growth Conditions ◽  
Sensor Kinase ◽  
Two Component System ◽  
Direct Signal ◽  
Two Component

ABSTRACT The Arc two-component system, comprising the ArcB sensor kinase and the ArcA response regulator, modulates the expression of numerous genes in response to the respiratory growth conditions. Under anoxic growth conditions ArcB autophosphorylates and transphosphorylates ArcA, which in turn represses or activates its target operons. The anaerobic metabolite d-lactate has been shown to stimulate the in vitro autophosphorylating activity of ArcB. In this study, the in vivo effect of d-lactate on the kinase activity of ArcB was assessed. The results demonstrate that d-lactate does not act as a direct signal for activation of ArcB, as previously proposed, but acts as a physiologically significant effector that amplifies ArcB kinase activity.

scholarly journals Catabolite Repression of the TodS/TodT Two-Component System and Effector-Dependent Transphosphorylation of TodT as the Basis for Toluene Dioxygenase Catabolic Pathway Control

2010 ◽  
Vol 192 (16) ◽  
pp. 4246-4250 ◽  
Author(s):  
Andreas Busch ◽  
Jesús Lacal ◽  
Hortencia Silva-Jímenez ◽  
Tino Krell ◽  
Juan L. Ramos
Keyword(s):  
Catabolite Repression ◽  
Response Regulator ◽  
Two Component System ◽  
Initiation Point ◽  
Component System ◽  
Toluene Dioxygenase ◽  
Regulatory Cascade ◽  
Two Component ◽  
Low Levels ◽  
Cognate Response Regulator

ABSTRACT The TodS/TodT two-component system of Pseudomonas putida regulates the expression of the toluene dioxygenase (tod) operon for the metabolism of toluene, benzene, and ethylbenzene. The sensor kinase TodS has a complex domain arrangement containing two functional modules, each harboring a sensor and an autokinase domain separated by a receiver domain. The TodT protein is the cognate response regulator that activates transcription of the toluene dioxygenase (TOD) pathway genes at the P todX promoter. We report in this study that the todST operon is transcribed from a main promoter and that the +1 initiation point is located 31 nucleotides upstream from the A of the first ATG codon and is preceded by a −10/−35 canonical promoter. Expression from P todS is under catabolite control, and in cells growing with glucose, the level of expression from this promoter is reduced, which in turn translates to low levels of the TodS/TodT regulators and results in a decrease of transcription from the P todX promoter. Thus, the main underlying regulatory mechanisms of the tod structural genes are at the levels of catabolite repression control from P todS and transcription activation, mediated by the TodT response regulator through a regulatory cascade in which the effector enhances autophosphorylation of TodS by ATP, with subsequent transphosphorylation of TodT.

scholarly journals Phosphorelay as the Sole Physiological Route of Signal Transmission by the Arc Two-Component System ofEscherichia coli

2000 ◽  
Vol 182 (13) ◽  
pp. 3858-3862 ◽  
Author(s):  
Ohsuk Kwon ◽  
Dimitris Georgellis ◽  
E. C. C. Lin
Keyword(s):  
Response Regulator ◽  
Signal Transmission ◽  
Phosphoryl Group ◽  
Sensor Kinase ◽  
Wild Type ◽  
Two Component System ◽  
Component System ◽  
Group Transfer ◽  
Two Component

ABSTRACT The Arc two-component system, comprising a tripartite sensor kinase (ArcB) and a response regulator (ArcA), modulates the expression of numerous genes involved in respiratory functions. In this study, the steps of phosphoryl group transfer from phosphorylated ArcB to ArcA were examined in vivo by using single copies of wild-type and mutantarcB alleles. The results indicate that the signal transmission occurs solely by His-Asp-His-Asp phosphorelay.

scholarly journals Activation of Bvg-Repressed Genes in Bordetella pertussis by RisA Requires Cross Talk from Noncooperonic Histidine Kinase RisK

2017 ◽  
Vol 199 (22) ◽  
Author(s):  
Qing Chen ◽  
Victoria Ng ◽  
Jason M. Warfel ◽  
Tod J. Merkel ◽  
Scott Stibitz
Keyword(s):  
Bordetella Pertussis ◽  
Histidine Kinase ◽  
Genomic Sequence ◽  
Response Regulator ◽  
Two Component System ◽  
Kinase Gene ◽  
Content Type ◽  
Reading Frame ◽  
Two Component

ABSTRACT The two-component response regulator RisA, encoded by open reading frame BP3554 in the Bordetella pertussis Tohama I genomic sequence, is a known activator of vrg genes, a set of genes whose expression is increased under the same environmental conditions (known as modulation) that result in repression of the bvgAS virulence regulon. Here we demonstrate that RisA is phosphorylated in vivo and that RisA phosphorylation is required for activation of vrg genes. An adjacent histidine kinase gene, risS, is truncated by frameshift mutation in B. pertussis but not in Bordetella bronchiseptica or Bordetella parapertussis. Neither deletion of risS′ or bvgAS nor phenotypic modulation with MgSO4 affected levels of phosphorylated RisA (RisA∼P) in B. pertussis. However, RisA phosphorylation did require the histidine kinase encoded by BP3223, here named RisK (cognate histidine kinase of RisA). RisK was also required for expression of the vrg genes. This requirement could be obviated by the introduction of the phosphorylation-mimicking RisAD60E mutant, indicating that an active conformation of RisA, but not phosphorylation per se, is crucial for vrg activation. Interestingly, expression of vrg genes is still modulated by MgSO4 in cells harboring the RisAD60E mutation, suggesting that the activated RisA senses additional signals to control vrg expression in response to environmental stimuli. IMPORTANCE In B. pertussis, the BvgAS two-component system activates the expression of virulence genes by binding of BvgA∼P to their promoters. Expression of the reciprocally regulated vrg genes requires RisA and is also repressed by the Bvg-activated BvgR. RisA is an OmpR-like response regulator, but RisA phosphorylation was not expected because the gene for its presumed, cooperonic, histidine kinase is inactivated by mutation. In this study, we demonstrate phosphorylation of RisA in vivo by a noncooperonic histidine kinase. We also show that RisA phosphorylation is necessary but not sufficient for vrg activation but, importantly, is not affected by BvgAS status. Instead, we propose that vrg expression is controlled by BvgAS through its regulation of BvgR, a cyclic di-GMP (c-di-GMP) phosphodiesterase.

scholarly journals The Lipoprotein NlpE Is a Cpx Sensor That Serves as a Sentinel for Protein Sorting and Folding Defects in theEscherichia coliEnvelope

2019 ◽  
Vol 201 (10) ◽  
Author(s):  
Antoine Delhaye ◽  
Géraldine Laloux ◽  
Jean-François Collet
Keyword(s):  
Outer Membrane ◽  
Two Component System ◽  
Oxidative Folding ◽  
Component System ◽  
Content Type ◽  
E Coli ◽  
Outer Membrane Lipoprotein ◽  
Physiological Relevance ◽  
Two Component ◽  
Membrane Lipoprotein

ABSTRACTThe envelope of Gram-negative bacteria is a complex compartment that is essential for viability. To ensure survival of the bacterial cells in fluctuating environments, several signal transduction systems, called envelope stress response systems (ESRSs), exist to monitor envelope biogenesis and homeostasis. The Cpx two-component system is an extensively studied ESRS inEscherichia colithat is active during exposure to a vast array of stresses and protects the envelope under those harmful circumstances. Overproduction of NlpE, a two-domain outer membrane lipoprotein of unclear function, has been used in numerous studies as a molecular trigger to turn on the system artificially. However, the mechanism of Cpx activation by NlpE, as well as its physiological relevance, awaited further investigation. In this paper, we provide novel insights into the role played by NlpE in the Cpx system. We found that, among all outer membrane lipoproteins inE. coli, NlpE is sufficient to induce Cpx when lipoprotein trafficking is perturbed. Under such conditions, fitness is increased by the presence of NlpE. Moreover, we show that NlpE, through its N-terminal domain, physically interacts with the Cpx sensor kinase CpxA. Our data suggest that NlpE also serves to activate the Cpx system during oxidative folding defects in the periplasm and that its C-terminal domain is involved in the sensing mechanism. Overall, our data demonstrate that NlpE acts as a sentinel for two important envelope biogenesis processes, namely, lipoprotein sorting and oxidative folding, and they further establish NlpE as a bona fide member of the Cpx two-component system.IMPORTANCEBacteria rely on a sophisticated envelope to shield them against challenging environmental conditions and therefore need to ensure correct envelope assembly and integrity. A major signaling pathway that performs this role in Gram-negative species is the Cpx system. An outer membrane lipoprotein of unclear function, NlpE, has long been exploited as a research tool to study Cpx inE. coli, since it triggers this system when overproduced or mislocalized; however, the mechanism and physiological relevance of the NlpE-Cpx connection have awaited further investigation. We elucidate a new function for NlpE by showing that it physically interacts with the Cpx sensor CpxA and acts as a sentinel that specifically monitors two essential envelope biogenesis processes, namely, lipoprotein sorting and oxidative folding.

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