scholarly journals Constitutive Mutations of the Salmonella entericaSerovar Typhimurium Transcriptional Virulence RegulatorphoP

2000 ◽  
Vol 68 (6) ◽  
pp. 3758-3762 ◽  
Author(s):  
John S. Gunn ◽  
Robert K. Ernst ◽  
Andrea J. McCoy ◽  
Samuel I. Miller
Keyword(s):  
Lipid A ◽  
Transcriptional Regulator ◽  
Inducible Promoter ◽  
Gene Induction ◽  
Two Component System ◽  
Regulatory Systems ◽  
Two Component ◽  
Biochemical Studies ◽  
Kinetics Of ◽  
Constitutive Mutant

ABSTRACT The PhoP-PhoQ two-component system is necessary for the virulence of Salmonella spp. and is responsible for regulating several modifications of the lipopolysaccharide (LPS). Mutagenesis of the transcriptional regulator phoP resulted in the identification of a mutant able to activate transcription of regulated genes ∼100-fold in the absence of PhoQ. Sequence analysis showed two single-base alterations resulting in amino acid changes at positions 93 (S93N) and 203 (Q203R). These mutations were individually created, and although each resulted in a constitutive phenotype, the double mutant displayed a synergistic effect both in the induction of PhoP-activated gene expression and in resistance to antimicrobial peptides. The constitutive phoP gene was placed under the control of an arabinose-inducible promoter to examine the kinetics of PhoP-activated gene induction and the resultant modifications of LPS. Gene induction and 2-hydroxymyristate modification of the lipid A were shown to occur within minutes of the addition of arabinose and to peak at 4 h. As the first constitutive mutant of phoP identified, this allele will be invaluable to future genetic and biochemical studies of this and likely other regulatory systems.

scholarly journals The Two-Component Regulatory System TCS08 Is Involved in Cellobiose Metabolism of Streptococcus pneumoniae R6

2006 ◽  
Vol 189 (4) ◽  
pp. 1342-1350 ◽  
Author(s):  
Stuart J. McKessar ◽  
Regine Hakenbeck
Keyword(s):  
Streptococcus Pneumoniae ◽  
Response Regulator ◽  
Regulatory System ◽  
Phosphotransferase System ◽  
Two Component System ◽  
Transcription Profiles ◽  
Regulatory Systems ◽  
Two Component ◽  
Cognate Response Regulator ◽  
Gram Positive Cocci

ABSTRACT The two-component system TCS08 is one of the regulatory systems that is important for virulence of Streptococcus pneumoniae. In order to investigate the TCS08 regulon, we have analyzed transcription profiles of mutants derived from S. pneumoniae R6 by microarray analysis. Since deletion mutants are often without a significant phenotype, we constructed a mutation in the histidine kinase HK08, T133P, in analogy to the phosphatase mutation T230P in the H box of the S. pneumoniae CiaH kinase described recently (D. Zähner, K. Kaminski, M. van der Linden, T. Mascher, M. Merai, and R. Hakenbeck, J. Mol. Microbiol. Biotechnol. 4:211-216, 2002). In addition, a deletion mutation was constructed in rr08, encoding the cognate response regulator. The most heavily suppressed genes in the hk08 mutant were spr0276 to spr0282, encoding a putative cellobiose phosphoenolpyruvate sugar phosphotransferase system (PTS). Whereas the R6 Smr parent strain and the Δrr08 mutant readily grew on cellobiose, the hk08 mutant and selected mutants with deletions in the PTS cluster did not, strongly suggesting that TCS08 is involved in the catabolism of cellobiose. Homologues of the TCS08 system were found in closely related streptococci and other gram-positive cocci. However, the genes spr0276 to spr0282, encoding the putative cellobiose PTS, represent a genomic island in S. pneumoniae and homologues were found in Streptococcus gordonii only, suggesting that this system might contribute to the pathogenicity potential of the pneumococcus.

scholarly journals A Versatile and Reliable Two-Component System for Tissue-Specific Gene Induction in Arabidopsis

2006 ◽  
Vol 141 (4) ◽  
pp. 1194-1204 ◽  
Author(s):  
Lukas Brand ◽  
Mirjam Hörler ◽  
Eveline Nüesch ◽  
Sara Vassalli ◽  
Philippa Barrell ◽  
...  
Keyword(s):  
Gene Induction ◽  
Specific Gene ◽  
Two Component System ◽  
Component System ◽  
Tissue Specific ◽  
Tissue Specific Gene ◽  
Two Component

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 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 The ChrA-ChrS and HrrA-HrrS Signal Transduction Systems Are Required for Activation of the hmuO Promoter and Repression of the hemA Promoter in Corynebacterium diphtheriae

2007 ◽  
Vol 75 (5) ◽  
pp. 2421-2431 ◽  
Author(s):  
Lori A. Bibb ◽  
Carey A. Kunkle ◽  
Michael P. Schmitt
Keyword(s):  
Corynebacterium Diphtheriae ◽  
Heme Iron ◽  
Dependent Manner ◽  
Two Component System ◽  
Component System ◽  
Regulatory Systems ◽  
Component Systems ◽  
Two Component ◽  
Genes Encoding ◽  
Two Component Systems

ABSTRACT Transcription of the Corynebacterium diphtheriae hmuO gene, which encodes a heme oxygenase involved in heme iron utilization, is activated in a heme- or hemoglobin-dependent manner in part by the two-component system ChrA-ChrS. Mutation of either the chrA or the chrS gene resulted in a marked reduction of hemoglobin-dependent activation at the hmuO promoter in C. diphtheriae; however, it was observed that significant levels of hemoglobin-dependent expression were maintained in the mutants, suggesting that an additional activator is involved in regulation. A BLAST search of the C. diphtheriae genome sequence revealed a second two-component system, encoded by DIP2268 and DIP2267, that shares similarity with ChrS and ChrA, respectively; we have designated these genes hrrS (DIP2268) and hrrA (DIP2267). Analysis of hmuO promoter expression demonstrated that hemoglobin-dependent activity was fully abolished in strains from which both the chrA-chrS and the hrrA-hrrS two-component systems were deleted. Similarly, deletion of the sensor kinase genes chrS and hrrS or the genes encoding both of the response regulators chrA and hrrA also eliminated hemoglobin-dependent activation at the hmuO promoter. We also show that the regulators ChrA-ChrS and HrrA-HrrS are involved in the hemoglobin-dependent repression of the promoter upstream of hemA, which encodes a heme biosynthesis enzyme. Evidence for cross talk between the ChrA-ChrS and HrrA-HrrS systems is presented. In conclusion, these findings demonstrate that the ChrA-ChrS and HrrA-HrrS regulatory systems are critical for full hemoglobin-dependent activation at the hmuO promoter and also suggest that these two-component systems are involved in the complex mechanism of the regulation of heme homeostasis in C. diphtheriae.

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.

Application of Onsager's Reciprocity Relations to Alloy Solidification

1988 ◽  
Vol 100 ◽  
Author(s):  
Theodore Kaplan ◽  
M. J. Aziz ◽  
L. J. Gray
Keyword(s):  
Phase Transformation ◽  
Two Component System ◽  
Interface Motion ◽  
Alloy Solidification ◽  
Moving Interface ◽  
Reciprocity Relations ◽  
Two Component ◽  
Thermodynamic Forces ◽  
Kinetics Of ◽  
Onsager’S Relations

ABSTRACTA requirement of any theory for the kinetics of interface motion during a phase transformation is that the force law which relates fluxes to thermodynamic forces satisfies Onsager's reciprocity relations. In this paper we show how to apply Onsager's relations to a phase transformation mediated by a moving interface in a two-component system. We use the result to evaluate two proposed models for interface motion during alloy solidification.

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 Induction of RpoS Degradation by the Two-Component System Regulator RstA in Salmonella enterica

2007 ◽  
Vol 189 (20) ◽  
pp. 7335-7342 ◽  
Author(s):  
María L. Cabeza ◽  
Andrés Aguirre ◽  
Fernando C. Soncini ◽  
Eleonora García Véscovi
Keyword(s):  
Salmonella Enterica ◽  
Response Regulator ◽  
Control Point ◽  
Bacterial Survival ◽  
Two Component System ◽  
Component System ◽  
Regulatory Pathways ◽  
Regulatory Systems ◽  
Two Component ◽  
Serovar Typhimurium

ABSTRACT Bacterial survival in diverse and changing environments relies on the accurate interplay between different regulatory pathways, which determine the design of an adequate adaptive response. The proper outcome depends on a precise gene expression profile generated from the finely tuned and concerted action of transcriptional factors of distinct regulatory hierarchies. Salmonella enterica serovar Typhimurium harbors multiple regulatory systems that are crucial for the bacterium to cope with harsh extra- and intracellular environments. In this work, we found that the expression of Salmonella RstA, a response regulator from the two-component system family, was able to downregulate the expression of three RpoS-controlled genes (narZ, spvA, and bapA). Furthermore, this downregulation was achieved by a reduction in RpoS cellular levels. The alternative sigma factor RpoS is critical for bacterial endurance under the most-stressful conditions, including stationary-phase entrance and host adaptation. Accordingly, RpoS cellular levels are tightly controlled by complex transcriptional, translational, and posttranslational mechanisms. The analysis of each regulatory step revealed that in Salmonella, RstA expression was able to promote RpoS degradation independently of the MviA-ClpXP proteolytic pathway. Additionally, we show that RstA is involved in modulating Salmonella biofilm formation. The fact that the RpoS-modulated genes affected by RstA expression have previously been demonstrated to contribute to Salmonella pathogenic traits, which include biofilm-forming capacity, suggests that under yet unknown conditions, RstA may function as a control point of RpoS-dependent pathways that govern Salmonella virulence.

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