scholarly journals Two-Component Response Regulators Ssk1p and Skn7p Additively Regulate High-Osmolarity Adaptation and Fungicide Sensitivity in Cochliobolus heterostrophus

2006 ◽  
Vol 6 (2) ◽  
pp. 171-181 ◽  
Author(s):  
Kosuke Izumitsu ◽  
Akira Yoshimi ◽  
Chihiro Tanaka
Keyword(s):  
Histidine Kinase ◽  
Response Regulator ◽  
Mitogen Activated Protein Kinase ◽  
Cochliobolus Heterostrophus ◽  
Response Regulators ◽  
Fungicide Sensitivity ◽  
High Osmolarity ◽  
Group Iii ◽  
Two Component ◽  
Moderate Resistance

ABSTRACT Filamentous ascomycetous fungi possess many histidine kinases and two conserved response regulators, Ssk1p and Skn7p, in their two-component signaling systems. We previously reported that the fungus unique group III histidine kinase regulates high-osmolarity adaptation and iprodione/fludioxonil fungicide sensitivity by controlling the phosphorylation of Hog1-type mitogen-activated protein kinase (MAPK) in filamentous ascomycetes. Here, we have characterized the response regulator genes ChSsk1 and ChSkn7 in the southern corn leaf blight fungus Cochliobolus heterostrophus. Both ChSsk1- and ChSkn7-disrupted mutants showed little sensitivity to high-osmolarity stress and moderate resistance to the iprodione/fludioxonil fungicides. The phosphorylation of Hog1-type MAPK BmHog1p induced by high-osmolarity stress and fungicide treatments was only regulated by ChSsk1p, indicating that ChSkn7p has roles in high-osmolarity adaptation and fungicide sensitivity that are independent from the activation of BmHog1p. The Chssk1 Chskn7 double mutants clearly showed higher sensitivity to osmolar stress and higher resistance to fungicides than the single mutants. The dose responses of the double mutants fit well with those of the group III histidine kinase-deficient strain. These results suggest that in filamentous ascomycetes, the Ssk1- and Skn7-type response regulators control high-osmolarity adaptation and fungicide sensitivity additively with differential mechanisms under the regulation of the group III histidine kinase. This study provides evidence that filamentous fungi have a unique two-component signaling system that is different from that of yeast and is responsible for high-osmolarity adaptation and fungicide sensitivity.

scholarly journals The Group III Two-Component Histidine Kinase of Filamentous Fungi Is Involved in the Fungicidal Activity of the Bacterial Polyketide Ambruticin

2008 ◽  
Vol 75 (1) ◽  
pp. 127-134 ◽  
Author(s):  
Anita Dongo ◽  
Nelly Bataill�-Simoneau ◽  
Claire Campion ◽  
Thomas Guillemette ◽  
Bruno Hamon ◽  
...  
Keyword(s):  
Filamentous Fungi ◽  
Histidine Kinase ◽  
Response Regulator ◽  
Alternaria Brassicicola ◽  
Mitogen Activated Protein Kinase ◽  
Natural Resistance ◽  
Single Amino Acid ◽  
Kinase Gene ◽  
Group Iii ◽  
Moderate Resistance

ABSTRACT We have shown that the plant pathogen Alternaria brassicicola exhibited very high susceptibility to ambruticin VS4 and to a lesser extent to the phenylpyrrole fungicide fludioxonil. These compounds are both derived from natural bacterial metabolites with antifungal properties and are thought to exert their toxicity by interfering with osmoregulation in filamentous fungi. Disruption of the osmosensor group III histidine kinase gene AbNIK1 (for A. brassicola NIK1) resulted in high levels of resistance to ambruticin and fludioxonil, while a mutant isolate characterized by a single-amino-acid substitution in the HAMP domain of the kinase only exhibited moderate resistance. Moreover, the natural resistance of Saccharomyces cerevisiae to these antifungal molecules switched to sensitivity in strains expressing AbNIK1p. We also showed that exposure to fludioxonil and ambruticin resulted in abnormal phosphorylation of a Hog1-like mitogen-activated protein kinase (MAPK) in A. brassicicola. Parallel experiments carried out with wild-type and mutant isolates of Neurospora crassa revealed that, in this species, ambruticin susceptibility was dependent on the OS1-RRG1 branch of the phosphorelay pathway downstream of the OS2 MAPK cascade but independent of the yeast Skn7-like response regulator RRG2. These results show that the ability to synthesize a functional group III histidine kinase is a prerequisite for the expression of ambruticin and phenylpyrrole susceptibility in A. brassicicola and N. crassa and that, at least in the latter species, improper activation of the high-osmolarity glycerol-related pathway could explain their fungicidal properties.

scholarly journals Molecular Characterization of Two-Component Systems of Helicobacter pylori

2000 ◽  
Vol 182 (8) ◽  
pp. 2068-2076 ◽  
Author(s):  
Dagmar Beier ◽  
Rainer Frank
Keyword(s):  
Helicobacter Pylori ◽  
Histidine Kinase ◽  
Response Regulator ◽  
Response Regulators ◽  
Reading Frame ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems

ABSTRACT Two-component systems are frequently involved in the adaptation of bacteria to changing environmental conditions at the level of transcriptional regulation. Here we report the characterization of members of the two-component systems of the gastric pathogenHelicobacter pylori deduced from the genome sequence of strain 26695. We demonstrate that the response regulators HP166, HP1043, and HP1021 have essential functions, as disruption of the corresponding genes is lethal for the bacteria, irrespective of the fact that HP1043 and HP1021 have nonconserved substitutions in crucial amino acids of their receiver domains. An analysis of the in vitro phosphorylation properties of the two-component proteins demonstrates that HP244-HP703 and HP165-HP166 are cognate histidine kinase-response regulator pairs. Furthermore, we provide evidence that the variability of the histidine kinase HP165 caused by a poly(C) tract of variable length close to the 3′ end of open reading frame 165/164 does not interfere with the kinase activity of the transmitter domain of HP165.

scholarly journals Allosteric Activation of Bacterial Response Regulators: the Role of the Cognate Histidine Kinase Beyond Phosphorylation

mBio ◽  
2014 ◽  
Vol 5 (6) ◽  
Author(s):  
Felipe Trajtenberg ◽  
Daniela Albanesi ◽  
Natalia Ruétalo ◽  
Horacio Botti ◽  
Ariel E. Mechaly ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Histidine Kinase ◽  
Response Regulator ◽  
Activation Mechanism ◽  
Response Regulators ◽  
Content Type ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems

ABSTRACT Response regulators are proteins that undergo transient phosphorylation, connecting specific signals to adaptive responses. Remarkably, the molecular mechanism of response regulator activation remains elusive, largely because of the scarcity of structural data on multidomain response regulators and histidine kinase/response regulator complexes. We now address this question by using a combination of crystallographic data and functional analyses in vitro and in vivo, studying DesR and its cognate sensor kinase DesK, a two-component system that controls membrane fluidity in Bacillus subtilis. We establish that phosphorylation of the receiver domain of DesR is allosterically coupled to two distinct exposed surfaces of the protein, controlling noncanonical dimerization/tetramerization, cooperative activation, and DesK binding. One of these surfaces is critical for both homodimerization- and kinase-triggered allosteric activations. Moreover, DesK induces a phosphorylation-independent activation of DesR in vivo, uncovering a novel and stringent level of specificity among kinases and regulators. Our results support a model that helps to explain how response regulators restrict phosphorylation by small-molecule phosphoryl donors, as well as cross talk with noncognate sensors. IMPORTANCE The ability to sense and respond to environmental variations is an essential property for cell survival. Two-component systems mediate key signaling pathways that allow bacteria to integrate extra- or intracellular signals. Here we focus on the DesK/DesR system, which acts as a molecular thermometer in B. subtilis, regulating the cell membrane’s fluidity. Using a combination of complementary approaches, including determination of the crystal structures of active and inactive forms of the response regulator DesR, we unveil novel molecular mechanisms of DesR’s activation switch. In particular, we show that the association of the cognate histidine kinase DesK triggers DesR activation beyond the transfer of the phosphoryl group. On the basis of sequence and structural analyses of other two-component systems, this activation mechanism appears to be used in a wide range of sensory systems, contributing a further level of specificity control among different signaling pathways.

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.

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 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.

Identification of genes required for different stages of dendritic swarming in Bacillus subtilis, with a novel role for phrC

Microbiology ◽  
2009 ◽  
Vol 155 (2) ◽  
pp. 398-412 ◽  
Author(s):  
Kassem Hamze ◽  
Daria Julkowska ◽  
Sabine Autret ◽  
Krzysztof Hinc ◽  
Krzysztofa Nagorska ◽  
...  
Keyword(s):  
Histidine Kinase ◽  
Cytoplasmic Membrane ◽  
Mutational Analysis ◽  
Response Regulator ◽  
Liquid Cultures ◽  
Global Regulators ◽  
Two Component ◽  
Control Production ◽  
Surfactin Production ◽  
First Time

Highly branched dendritic swarming of B. subtilis on synthetic B-medium involves a developmental-like process that is absolutely dependent on flagella and surfactin secretion. In order to identify new swarming genes, we targeted the two-component ComPA signalling pathway and associated global regulators. In liquid cultures, the histidine kinase ComP, and the response regulator ComA, respond to secreted pheromones ComX and CSF (encoded by phrC) in order to control production of surfactin synthases and ComS (competence regulator). In this study, for what is believed to be the first time, we established that distinct early stages of dendritic swarming can be clearly defined, and that they are amenable to genetic analysis. In a mutational analysis producing several mutants with distinctive phenotypes, we were able to assign the genes sfp (activation of surfactin synthases), comA, abrB and codY (global regulators), hag (flagellin), mecA and yvzB (hag-like), and swrB (motility), to the different swarming stages. Surprisingly, mutations in genes comPX, comQ, comS, rapC and oppD, which are normally indispensable for import of CSF, had only modest effects, if any, on swarming and surfactin production. Therefore, during dendritic swarming, surfactin synthesis is apparently subject to novel regulation that is largely independent of the ComXP pathway; we discuss possible alternative mechanisms for driving srfABCD transcription. We showed that the phrC mutant, largely independent of any effect on surfactin production, was also, nevertheless, blocked early in swarming, forming stunted dendrites, with abnormal dendrite initiation morphology. In a mixed swarm co-inoculated with phrC sfp+ and phrC+ sfp (GFP), an apparently normal swarm was produced. In fact, while initiation of all dendrites was of the abnormal phrC type, these were predominantly populated by sfp cells, which migrated faster than the phrC cells. This and other results indicated a specific migration defect in the phrC mutant that could not be trans-complemented by CSF in a mixed swarm. CSF is the C-terminal pentapeptide of the surface-exposed PhrC pre-peptide and we propose that the residual PhrC 35 aa residue peptide anchored in the exterior of the cytoplasmic membrane has an apparently novel extracellular role in swarming.

scholarly journals Functional reconstitution of the Salmonella typhimurium PhoQ histidine kinase sensor in proteoliposomes

2005 ◽  
Vol 390 (3) ◽  
pp. 769-776 ◽  
Author(s):  
Sarah Sanowar ◽  
Hervé Le Moual
Keyword(s):  
Salmonella Typhimurium ◽  
Histidine Kinase ◽  
Catalytic Domain ◽  
Response Regulator ◽  
Phosphoryl Group ◽  
Two Component ◽  
Two Component Signal Transduction ◽  
High Concentrations

Two-component signal-transduction systems are widespread in bacteria. They are usually composed of a transmembrane histidine kinase sensor and a cytoplasmic response regulator. The PhoP/PhoQ two-component system of Salmonella typhimurium contributes to virulence by co-ordinating the adaptation to low concentrations of environmental Mg2+. Limiting concentrations of extracellular Mg2+ activate the PhoP/PhoQ phosphorylation cascade modulating the transcription of PhoP-regulated genes. In contrast, high concentrations of extracellular Mg2+ stimulate the dephosphorylation of the response regulator PhoP by the PhoQ kinase sensor. In the present study, we report the purification and functional reconstitution of PhoQHis, a PhoQ variant with a C-terminal His tag, into Escherichia coli liposomes. The functionality of PhoQHis was essentially similar to that of PhoQ as shown in vivo and in vitro. Purified PhoQHis was inserted into liposomes in a unidirectional orientation, with the sensory domain facing the lumen and the catalytic domain facing the extraluminal environment. Reconstituted PhoQHis exhibited all the catalytic activities that have been described for histidine kinase sensors. Reconstituted PhoQHis was capable of autokinase activity when incubated in the presence of Mg2+-ATP. The phosphoryl group could be transferred from reconstituted PhoQHis to PhoP. Reconstituted PhoQHis catalysed the dephosphorylation of phospho-PhoP and this activity was stimulated by the addition of extraluminal ADP.

scholarly journals A Novel Redox-Sensing Histidine Kinase That Controls Carbon Catabolite Repression inAzoarcussp. CIB

mBio ◽  
2019 ◽  
Vol 10 (2) ◽  
Author(s):  
J. Andrés Valderrama ◽  
Helena Gómez-Álvarez ◽  
Zaira Martín-Moldes ◽  
M. Álvaro Berbís ◽  
F. Javier Cañada ◽  
...  
Keyword(s):  
Aromatic Compounds ◽  
Histidine Kinase ◽  
Catabolite Repression ◽  
Carbon Catabolite Repression ◽  
Response Regulator ◽  
Sensor Kinase ◽  
General Role ◽  
Two Component ◽  
Redox Switch ◽  
Redox Sensing

ABSTRACTWe have identified and characterized the AccS multidomain sensor kinase that mediates the activation of the AccR master regulator involved in carbon catabolite repression (CCR) of the anaerobic catabolism of aromatic compounds inAzoarcussp. CIB. A truncated AccS protein that contains only the soluble C-terminal autokinase module (AccS′) accounts for the succinate-dependent CCR control. In vitroassays with purified AccS′ revealed its autophosphorylation, phosphotransfer from AccS′∼P to the Asp60 residue of AccR, and the phosphatase activity toward its phosphorylated response regulator, indicating that the equilibrium between the kinase and phosphatase activities of AccS′ may control the phosphorylation state of the AccR transcriptional regulator. Oxidized quinones, e.g., ubiquinone 0 and menadione, switched the AccS′ autokinase activity off, and three conserved Cys residues, which are not essential for catalysis, are involved in such inhibition. Thiol oxidation by quinones caused a change in the oligomeric state of the AccS′ dimer resulting in the formation of an inactive monomer. This thiol-based redox switch is tuned by the cellular energy state, which can change depending on the carbon source that the cells are using. This work expands the functional diversity of redox-sensitive sensor kinases, showing that they can control new bacterial processes such as CCR of the anaerobic catabolism of aromatic compounds. The AccSR two-component system is conserved in the genomes of some betaproteobacteria, where it might play a more general role in controlling the global metabolic state according to carbon availability.IMPORTANCETwo-component signal transduction systems comprise a sensor histidine kinase and its cognate response regulator, and some have evolved to sense and convert redox signals into regulatory outputs that allow bacteria to adapt to the altered redox environment. The work presented here expands knowledge of the functional diversity of redox-sensing kinases to control carbon catabolite repression (CCR), a phenomenon that allows the selective assimilation of a preferred compound among a mixture of several carbon sources. The newly characterized AccS sensor kinase is responsible for the phosphorylation and activation of the AccR master regulator involved in CCR of the anaerobic degradation of aromatic compounds in the betaproteobacteriumAzoarcussp. CIB. AccS seems to have a thiol-based redox switch that is modulated by the redox state of the quinone pool. The AccSR system is conserved in several betaproteobacteria, where it might play a more general role controlling their global metabolic state.

scholarly journals The Eukaryotic Two-Component Histidine Kinase Sln1p RegulatesOCH1via the Transcription Factor, Skn7p

2002 ◽  
Vol 13 (2) ◽  
pp. 412-424 ◽  
Author(s):  
Sheng Li ◽  
Susan Dean ◽  
Zhijian Li ◽  
Joe Horecka ◽  
Robert J. Deschenes ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Osmotic Stress ◽  
Binding Site ◽  
Histidine Kinase ◽  
Response Regulators ◽  
Hog Pathway ◽  
Receiver Domain ◽  
Osmotic Response ◽  
Two Component

The yeast “two-component” osmotic stress phosphorelay consists of the histidine kinase, Sln1p, the phosphorelay intermediate, Ypd1p and two response regulators, Ssk1p and Skn7p, whose activities are regulated by phosphorylation of a conserved aspartyl residue in the receiver domain. Dephospho-Ssk1p leads to activation of the hyper-osmotic response (HOG) pathway, whereas phospho-Skn7p presumably leads to activation of hypo-osmotic response genes. The multifunctional Skn7 protein is important in oxidative as well as osmotic stress; however, the Skn7p receiver domain aspartate that is the phosphoacceptor in the SLN1 pathway is dispensable for oxidative stress. Like many well-characterized bacterial response regulators, Skn7p is a transcription factor. In this report we investigate the role of Skn7p in osmotic response gene activation. Our studies reveal that the Skn7p HSF-like DNA binding domain interacts with acis-acting element identified upstream ofOCH1 that is distinct from the previously defined HSE-like Skn7p binding site. Our data support a model in which Skn7p receiver domain phosphorylation affects transcriptional activation rather than DNA binding to this class of DNA binding site.

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