scholarly journals New Roles for Two-Component System Response Regulators of Salmonella enterica Serovar Typhi during Host Cell Interactions

2020 ◽  
Vol 8 (5) ◽  
pp. 722
Author(s):  
Claudie Murret-Labarthe ◽  
Maud Kerhoas ◽  
Karine Dufresne ◽  
France Daigle
Keyword(s):  
Salmonella Enterica ◽  
Pathogenic Bacteria ◽  
Response Regulator ◽  
Transcriptional Response ◽  
Host Cells ◽  
System Response ◽  
Response Regulators ◽  
Salmonella Enterica Serovar Typhi ◽  
Two Component ◽  
External Stresses

In order to survive external stresses, bacteria need to adapt quickly to changes in their environment. One adaptive mechanism is to coordinate and alter their gene expression by using two-component systems (TCS). TCS are composed of a sensor kinase that activates a transcriptional response regulator by phosphorylation. TCS are involved in motility, virulence, nutrient acquisition, and envelope stress in many bacteria. The pathogenic bacteria Salmonella enterica serovar Typhi (S. Typhi) possess 30 TCSs, is specific to humans, and causes typhoid fever. Here, we have individually deleted each of the 30 response regulators. We have determined their role during interaction with host cells (epithelial cells and macrophages). Deletion of most of the systems (24 out of 30) resulted in a significant change during infection. We have identified 32 new phenotypes associated with TCS of S. Typhi. Some previously known phenotypes associated with TCSs in Salmonella were also confirmed. We have also uncovered phenotypic divergence between Salmonella serovars, as distinct phenotypes between S. Typhi and S. Typhimurium were identified for cpxR. This finding highlights the importance of specifically studying S. Typhi to understand its pathogenesis mechanisms and to develop strategies to potentially reduce typhoid infections.

scholarly journals New roles for two-component system response regulators of Salmonella enterica serovar Typhi during host cell interactions

2019 ◽  
Author(s):  
Claudie Murret-Labarthe ◽  
Maud Kerhoas ◽  
Karine Dufresne ◽  
France Daigle
Keyword(s):  
Salmonella Enterica ◽  
Pathogenic Bacteria ◽  
Response Regulator ◽  
Transcriptional Response ◽  
Host Cells ◽  
System Response ◽  
Response Regulators ◽  
Two Component ◽  
Host Cell Interactions ◽  
External Stresses

AbstractIn order to survive external stresses, bacteria need to adapt quickly to changes in their environment. One adaptive mechanism is to coordinate and alter their gene expression by using two-component systems (TCS). TCS are composed of a sensor kinase that activates a transcriptional response regulator by phosphorylation. TCS are involved in motility, virulence, nutrient acquisition, and envelope stress in many bacteria. The pathogenic bacteria Salmonella enterica serovar Typhi (S. Typhi) possess 30 TCSs, is specific to humans and causes typhoid fever. Here, we have deleted individually each of the 30 response regulators. We have determined their role during interaction with host cells (epithelial cells and macrophages). Deletion of most of the systems (24 out of 30) resulted in a significantly change during infection, either lower or higher than the wild-type strain. We have identified 32 new phenotypes associated with TCS of S. Typhi. Some previously known phenotypes associated with TCSs in Salmonella were also confirmed. We have also uncovered phenotypic divergence between Salmonella serovars as distinct phenotypes between S. Typhi and S. Typhimurium were identified for cpxR. This highlight the importance of specifically studying S. Typhi to understand its pathogenesis mechanisms and to develop strategies to potentially reduce typhoid infections.

scholarly journals Role of Salmonella enterica Serovar Typhimurium Two-Component System PreA/PreB in Modulating PmrA-Regulated Gene Transcription

2006 ◽  
Vol 188 (1) ◽  
pp. 141-149 ◽  
Author(s):  
Massimo Merighi ◽  
Amanda Carroll-Portillo ◽  
Alecia N. Septer ◽  
Aditi Bhatiya ◽  
John S. Gunn
Keyword(s):  
Salmonella Enterica ◽  
Target Genes ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Response Regulator ◽  
Polymyxin B ◽  
Response Regulators ◽  
Two Component System ◽  
Component System ◽  
Two Component ◽  
Serovar Typhimurium

ABSTRACT The PmrA/PmrB two-component system encoded by the pmrCAB operon regulates the modification of Salmonella enterica serovar Typhimurium lipopolysaccharide leading to polymyxin B resistance. PmrA and PhoP are the only known activators of pmrCAB. A transposon mutagenesis screen for additional regulators of a pmrC::MudJ fusion led to the identification of a two-component system, termed PreA/PreB (pmrCAB regulators A and B), that controls the transcription of the pmrCAB operon in response to unknown signals. The initial observations indicated that insertions in, or a deletion of, the preB sensor, but not the preA response regulator, caused upregulation of pmrCAB. Interestingly, the expression of pmrCAB was not upregulated in a preAB mutant grown in LB broth, implicating PreA in the increased expression of pmrCAB in the preB strain. This was confirmed by overexpression of preA + in preAB or preB backgrounds, which resulted in significant upregulation or further upregulation of pmrCAB. No such effect was observed in any tested preB + backgrounds. Additionally, an ectopic construct expressing a preA[D51A] allele also failed to upregulate pmrC in any of the pre backgrounds tested, which implies that there is a need for phosphorylation in the activation of the target genes. The observed upregulation of pmrCAB occurred independently of the response regulators PmrA and PhoP. Although a preB mutation led to increased transcription of pmrCAB, this did not result in a measurable effect on polymyxin B resistance. Our genetic data support a model of regulation whereby, in response to unknown signals, the PreB sensor activates PreA, which in turn indirectly upregulates pmrCAB transcription.

scholarly journals FixJ family regulator AcfR of Azorhizobium caulinodans is involved in symbiosis with the host plant

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Wei Liu ◽  
Xue Bai ◽  
Yan Li ◽  
Haikun Zhang ◽  
Xiaoke Hu
Keyword(s):  
Signal Transduction ◽  
Host Plant ◽  
Type Strain ◽  
Wild Type Strain ◽  
Response Regulator ◽  
Azorhizobium Caulinodans ◽  
Wild Type ◽  
Response Regulators ◽  
Free Living ◽  
Two Component

Abstract Background A wide variety of bacterial adaptative responses to environmental conditions are mediated by signal transduction pathways. Two-component signal transduction systems are one of the predominant means used by bacteria to sense the signals of the host plant and adjust their interaction behaviour. A total of seven open reading frames have been identified as putative two-component response regulators in the gram-negative nitrogen-fixing bacteria Azorhizobium caulinodans ORS571. However, the biological functions of these response regulators in the symbiotic interactions between A. caulinodans ORS571 and the host plant Sesbania rostrata have not been elucidated to date. Results In this study, we identified and investigated a two-component response regulator, AcfR, with a phosphorylatable N-terminal REC (receiver) domain and a C-terminal HTH (helix-turn-helix) LuxR DNA-binding domain in A. caulinodans ORS571. Phylogenetic analysis showed that AcfR possessed close evolutionary relationships with NarL/FixJ family regulators. In addition, six histidine kinases containing HATPase_c and HisKA domains were predicted to interact with AcfR. Furthermore, the biological function of AcfR in free-living and symbiotic conditions was elucidated by comparing the wild-type strain and the ΔacfR mutant strain. In the free-living state, the cell motility behaviour and exopolysaccharide production of the ΔacfR mutant were significantly reduced compared to those of the wild-type strain. In the symbiotic state, the ΔacfR mutant showed a competitive nodule defect on the stems and roots of the host plant, suggesting that AcfR can provide A. caulinodans with an effective competitive ability for symbiotic nodulation. Conclusions Our results showed that AcfR, as a response regulator, regulates numerous phenotypes of A. caulinodans under the free-living conditions and in symbiosis with the host plant. The results of this study help to elucidate the involvement of a REC + HTH_LuxR two-component response regulator in the Rhizobium-host plant interaction.

scholarly journals Multiple Mechanisms of Action for Inhibitors of Histidine Protein Kinases from Bacterial Two-Component Systems

1999 ◽  
Vol 43 (7) ◽  
pp. 1693-1699 ◽  
Author(s):  
Jamese J. Hilliard ◽  
Raul M. Goldschmidt ◽  
Lisa Licata ◽  
Ellen Z. Baum ◽  
Karen Bush
Keyword(s):  
Pathogenic Bacteria ◽  
Response Regulator ◽  
Membrane Integrity ◽  
Bacterial Killing ◽  
Gram Positive Bacteria ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems ◽  
Bacterial Cell Membrane ◽  
Cellular Incorporation

ABSTRACT Many pathogenic bacteria utilize two-component systems consisting of a histidine protein kinase (HPK) and a response regulator (RR) for signal transduction. During the search for novel inhibitors, several chemical series, including benzoxazines, benzimidazoles, bis-phenols, cyclohexenes, trityls, and salicylanilides, were identified that inhibited the purified HPK-RR pairs KinA-Spo0F and NRII-NRI, with 50% inhibitory concentrations (IC50s) ranging from 1.9 to >500 μM and MICs ranging from 0.5 to >16 μg/ml for gram-positive bacteria. However, additional observations suggested that mechanisms other than HPK inhibition might contribute to antibacterial activity. In the present work, representative compounds from the six different series of inhibitors were analyzed for their effects on membrane integrity and macromolecular synthesis. At 4× MIC, 17 of 24 compounds compromised the integrity of the bacterial cell membrane within 10 min, as measured by uptake of propidium iodide. In this set, compounds with lower IC50s tended to cause greater membrane disruption. Eleven of 12 compounds inhibited cellular incorporation of radiolabeled thymidine and uridine >97% in 5 min and amino acids >80% in 15 min. The HPK inhibitor that allowed >25% precursor incorporation had no measurable MIC (>16 μg/ml). Fifteen of 24 compounds also caused hemolysis of equine erythrocytes. Thus, the antibacterial HPK inhibitors caused a rapid decrease in cellular incorporation of RNA, DNA, and protein precursors, possibly as a result of the concomitant disruption of the cytoplasmic membrane. Bacterial killing by these HPK inhibitors may therefore be due to multiple mechanisms, independent of HPK inhibition.

scholarly journals Transcriptional response in the peripheral blood of patients infected with Salmonella enterica serovar Typhi

2009 ◽  
Vol 106 (52) ◽  
pp. 22433-22438 ◽  
Author(s):  
Lucinda J. Thompson ◽  
Sarah J. Dunstan ◽  
Christiane Dolecek ◽  
Tim Perkins ◽  
Deborah House ◽  
...  
Keyword(s):  
Peripheral Blood ◽  
Salmonella Enterica ◽  
Transcriptional Response ◽  
Salmonella Enterica Serovar Typhi

scholarly journals Multiple Factors Independently RegulatehilA and Invasion Gene Expression in Salmonella enterica Serovar Typhimurium

2000 ◽  
Vol 182 (7) ◽  
pp. 1872-1882 ◽  
Author(s):  
Robin L. Lucas ◽  
C. Phoebe Lostroh ◽  
Concetta C. DiRusso ◽  
Michael P. Spector ◽  
Barry L. Wanner ◽  
...  
Keyword(s):  
Gene Expression ◽  
Salmonella Enterica ◽  
Inorganic Phosphate ◽  
Response Regulator ◽  
Regulatory System ◽  
Negative Control ◽  
Host Cells ◽  
Uptake System ◽  
Intracellular Signals ◽  
Serovar Typhimurium

HilA activates the expression of Salmonella entericaserovar Typhimurium invasion genes. To learn more about regulation ofhilA, we isolated Tn5 mutants exhibiting reduced hilA and/or invasion gene expression. In addition to expected mutations, we identified Tn5 insertions inpstS, fadD, flhD, flhC, and fliA. Analysis of the pstS mutant indicates that hilA and invasion genes are repressed by the response regulator PhoB in the absence of the Pst high-affinity inorganic phosphate uptake system. This system is required for negative control of the PhoR-PhoB two-component regulatory system, suggesting thathilA expression may be repressed by PhoR-PhoB under low extracellular inorganic phosphate conditions. FadD is required for uptake and degradation of long-chain fatty acids, and our analysis of the fadD mutant indicates that hilA is regulated by a FadD-dependent, FadR-independent mechanism. Thus, fatty acid derivatives may act as intracellular signals to regulatehilA expression. flhDC and fliAencode transcription factors required for flagellum production, motility, and chemotaxis. Complementation studies with flhCand fliA mutants indicate that FliZ, which is encoded in an operon with fliA, activates expression of hilA, linking regulation of hilA with motility. Finally, epistasis tests showed that PhoB, FadD, FliZ, SirA, and EnvZ act independently to regulate hilA expression and invasion. In summary, our screen has identified several distinct pathways that can modulate S. enterica serovar Typhimurium's ability to express hilA and invade host cells. Integration of signals from these different pathways may help restrict invasion gene expression during infection.

Histidine kinases in signal transduction pathways of eukaryotes

1997 ◽  
Vol 110 (10) ◽  
pp. 1141-1145 ◽  
Author(s):  
W.F. Loomis ◽  
G. Shaulsky ◽  
N. Wang
Keyword(s):  
Signal Transduction ◽  
Response Regulator ◽  
Signal Transduction Pathways ◽  
Response Regulators ◽  
Histidine Kinases ◽  
Camp Phosphodiesterase ◽  
Wide Range ◽  
Two Component ◽  
Two Component Signal Transduction ◽  
Dependent Protein

Autophosphorylating histidine kinases are an ancient conserved family of enzymes that are found in eubacteria, archaebacteria and eukaryotes. They are activated by a wide range of extracellular signals and transfer phosphate moieties to aspartates found in response regulators. Recent studies have shown that such two-component signal transduction pathways mediate osmoregulation in Saccharomyces cerevisiae, Dictyostelium discoideum and Neurospora crassa. Moreover, they play pivotal roles in responses of Arabidopsis thaliana to ethylene and cytokinin. A transmembrane histidine kinase encoded by dhkA accumulates when Dictyostelium cells aggregate during development. Activation of DhkA results in the inhibition of its response regulator, RegA, which is a cAMP phosphodiesterase that regulates the cAMP dependent protein kinase PKA. When PKA is activated late in the differentiation of prespore cells, they encapsulate into spores. There is evidence that this two-component system participates in a feedback loop linked to PKA in prestalk cells such that the signal to initiate encapsulation is rapidly amplified. Such signal transduction pathways can be expected to be found in a variety of eukaryotic differentiations since they are rapidly reversible and can integrate disparate signals.

scholarly journals Quinazoline-Based Antivirulence Compounds Selectively Target Salmonella PhoP/PhoQ Signal Transduction System

2019 ◽  
Vol 64 (1) ◽  
Author(s):  
María Ayelén Carabajal ◽  
Christopher R. M. Asquith ◽  
Tuomo Laitinen ◽  
Graham J. Tizzard ◽  
Lucía Yim ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Salmonella Enterica ◽  
Pathogenic Bacteria ◽  
Catalytic Domain ◽  
Kinase Inhibitor ◽  
Adaptive Responses ◽  
Antibacterial Compounds ◽  
Content Type ◽  
Two Component ◽  
Serovar Typhimurium

ABSTRACT The rapid emergence of multidrug resistance among bacterial pathogens has become a significant challenge to human health in our century. Therefore, development of next-generation antibacterial compounds is an urgent need. Two-component signal transduction systems (TCS) are stimulus-response coupling devices that allow bacteria to sense and elaborate adaptive responses to changing environmental conditions, including the challenges that pathogenic bacteria face inside the host. The differential presence of TCS, present in bacteria but absent in the animal kingdom, makes them attractive targets in the search for new antibacterial compounds. In Salmonella enterica, the PhoP/PhoQ two-component system controls the expression of crucial phenotypes that define the ability of the pathogen to establish infection in the host. We now report the screening of 686 compounds from a GlaxoSmithKline published kinase inhibitor set in a high-throughput whole-cell assay that targets Salmonella enterica serovar Typhimurium PhoP/PhoQ. We identified a series of quinazoline compounds that showed selective and potent downregulation of PhoP/PhoQ-activated genes and define structural attributes required for their efficacy. We demonstrate that their bioactivity is due to repression of the PhoQ sensor autokinase activity mediated by interaction with its catalytic domain, acting as competitive inhibitors of ATP binding. While noncytotoxic, the hit molecules exhibit antivirulence effect by blockage of S. Typhimurium intramacrophage replication. Together, these features make these quinazoline compounds stand out as exciting leads to develop a therapeutic intervention to fight salmonellosis.

scholarly journals Role of two-component sensory systems of Salmonella enterica serovar Dublin in the pathogenesis of systemic salmonellosis in cattle

Microbiology ◽  
2010 ◽  
Vol 156 (10) ◽  
pp. 3108-3122 ◽  
Author(s):  
Gillian D. Pullinger ◽  
Pauline M. van Diemen ◽  
Francis Dziva ◽  
Mark P. Stevens
Keyword(s):  
Salmonella Enterica ◽  
Response Regulator ◽  
Systemic Disease ◽  
Lymphatic Vessels ◽  
Intestinal Barrier ◽  
Systemic Infection ◽  
Oral Route ◽  
Systematic Analysis ◽  
Two Component

Salmonella enterica serovar Dublin (S. Dublin) is associated with enteritis, typhoid and abortion in cattle. Infections are acquired by the oral route, and the bacteria transit through varied anatomical and cellular niches to elicit systemic disease. S. Dublin must therefore sense and respond to diverse extrinsic stimuli to control gene expression in a spatial and temporal manner. Two-component systems (TCSs) play key roles in such processes, and typically contain a membrane-associated sensor kinase (SK) that modifies a cognate response regulator. Analysis of the genome sequence of S. Dublin identified 31 conserved SK genes. Each SK gene was separately disrupted by lambda Red recombinase-mediated insertion of transposons harbouring unique sequence tags. Calves were challenged with a pool of the mutants together with control strains of defined virulence by the oral and intravenous routes. Quantification of tagged mutants in output pools derived from various tissues and cannulated lymphatic vessels allowed the assignment of spatial roles for each SK following oral inoculation or when the intestinal barrier was bypassed by intravenous delivery. Mutant phenotypes were also assigned in cultured intestinal epithelial cells. Mutants with insertions in barA, envZ, phoQ, ssrA or qseC were significantly negatively selected at all enteric and systemic sites sampled after oral dosing. Mutants lacking baeS, dpiB or citA were negatively selected at some but not all sites. After intravenous inoculation, only barA and phoQ mutants were significantly under-represented at systemic sites. The novel role of baeS in intestinal colonization was confirmed by oral co-infection studies, with a mutant exhibiting modest but significant attenuation at a number of enteric sites. This is the first systematic analysis of the role of all Salmonella TCSs in a highly relevant model of enteric fever. Spatial roles were assigned to eight S. Dublin SKs, but most were not essential for intestinal or systemic infection of the target host.

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