scholarly journals Activation of the Campylobacter jejuni FlgSR Two-Component System Is Linked to the Flagellar Export Apparatus

2009 ◽  
Vol 191 (8) ◽  
pp. 2656-2667 ◽  
Author(s):  
Stephanie N. Joslin ◽  
David R. Hendrixson
Keyword(s):  
Gene Expression ◽  
Campylobacter Jejuni ◽  
Response Regulator ◽  
Regulatory System ◽  
Two Component System ◽  
Regulatory Cascade ◽  
Regulatory Systems ◽  
Two Component ◽  
Flagellar Protein ◽  
Flagellar Genes

ABSTRACT Activation of σ54-dependent gene expression essential for formation of flagella in Campylobacter jejuni requires the components of the inner membrane-localized flagellar export apparatus and the FlgSR two-component regulatory system. In this study, we characterized the FlgS sensor kinase and how activation of the protein is linked to the flagellar export apparatus. We found that FlgS is localized to the C. jejuni cytoplasm and that His141 of FlgS is essential for autophosphorylation, phosphorelay to the cognate FlgR response regulator, motility, and expression of σ54-dependent flagellar genes. Mutants with incomplete flagellar export apparatuses produced wild-type levels of FlgS and FlgR, but they were defective for signaling through the FlgSR system. By using genetic approaches, we found that FlgSR activity is linked to and downstream of the flagellar export apparatus in a regulatory cascade that terminates in expression of σ54-dependent flagellar genes. By analyzing defined flhB and fliI mutants of C. jejuni that form flagellar export apparatuses that are secretion incompetent, we determined that formation of the apparatus is required to contribute to the signal sensed by FlgS to terminate in activation of expression of σ54-dependent flagellar genes. Considering that the flagellar export apparatuses of Escherichia coli and Salmonella species influence σ28-dependent flagellar gene expression, our work expands the signaling activity of the apparatuses to include σ54-dependent pathways of C. jejuni and possibly other motile bacteria. This study indicates that these apparatuses have broader functions beyond flagellar protein secretion, including activation of essential two-component regulatory systems required for expression of σ54-dependent flagellar genes.

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 Identification of a Second Two-Component Signal Transduction System That Controls Fosfomycin Tolerance and Glycerol-3-Phosphate Uptake

2014 ◽  
Vol 197 (5) ◽  
pp. 861-871 ◽  
Author(s):  
Kumiko Kurabayashi ◽  
Yuko Hirakawa ◽  
Koichi Tanimoto ◽  
Haruyoshi Tomita ◽  
Hidetada Hirakawa
Keyword(s):  
Phosphate Uptake ◽  
Response Regulator ◽  
Anaerobic Respiration ◽  
Regulatory System ◽  
Carbon Substrate ◽  
Two Component System ◽  
Component System ◽  
Content Type ◽  
Two Component ◽  
Biological Cost

Particular interest in fosfomycin has resurfaced because it is a highly beneficial antibiotic for the treatment of refractory infectious diseases caused by pathogens that are resistant to other commonly used antibiotics. The biological cost to cells of resistance to fosfomycin because of chromosomal mutation is high. We previously found that a bacterial two-component system, CpxAR, induces fosfomycin tolerance in enterohemorrhagicEscherichia coli(EHEC) O157:H7. This mechanism does not rely on irreversible genetic modification and allows EHEC to relieve the fitness burden that results from fosfomycin resistance in the absence of fosfomycin. Here we show that another two-component system, TorSRT, which was originally characterized as a regulatory system for anaerobic respiration utilizing trimethylamine-N-oxide (TMAO), also induces fosfomycin tolerance. Activation of the Tor regulatory pathway by overexpression oftorR, which encodes the response regulator, or addition of TMAO increased fosfomycin tolerance in EHEC. We also show that phosphorylated TorR directly represses the expression ofglpT, a gene that encodes a symporter of fosfomycin and glycerol-3-phosphate, and activation of the TorR protein results in the reduced uptake of fosfomycin by cells. However, cells in which the Tor pathway was activated had an impaired growth phenotype when cultured with glycerol-3-phosphate as a carbon substrate. These observations suggest that the TorSRT pathway is the second two-component system to reversibly control fosfomycin tolerance and glycerol-3-phosphate uptake in EHEC, and this may be beneficial for bacteria by alleviating the biological cost. We expect that this mechanism could be a potential target to enhance the utility of fosfomycin as chemotherapy against multidrug-resistant pathogens.

scholarly journals FlhF and Its GTPase Activity Are Required for Distinct Processes in Flagellar Gene Regulation and Biosynthesis in Campylobacter jejuni

2009 ◽  
Vol 191 (21) ◽  
pp. 6602-6611 ◽  
Author(s):  
Murat Balaban ◽  
Stephanie N. Joslin ◽  
David R. Hendrixson
Keyword(s):  
Gene Expression ◽  
Gene Regulation ◽  
Campylobacter Jejuni ◽  
Regulatory System ◽  
Flagellar Gene ◽  
Gtpase Activity ◽  
Gtp Hydrolysis ◽  
Genetic Analyses ◽  
Flagellar Biosynthesis ◽  
Two Component

ABSTRACT FlhF proteins are putative GTPases that are often necessary for one or more steps in flagellar organelle development in polarly flagellated bacteria. In Campylobacter jejuni, FlhF is required for σ54-dependent flagellar gene expression and flagellar biosynthesis, but how FlhF influences these processes is unknown. Furthermore, the GTPase activity of any FlhF protein and the requirement of this speculated activity for steps in flagellar biosynthesis remain uncharacterized. We show here that C. jejuni FlhF hydrolyzes GTP, indicating that these proteins are GTPases. C. jejuni mutants producing FlhF proteins with reduced GTPase activity were not severely defective for σ54-dependent flagellar gene expression, unlike a mutant lacking FlhF. Instead, these mutants had a propensity to lack flagella or produce flagella in improper numbers or at nonpolar locations, indicating that GTP hydrolysis by FlhF is required for proper flagellar biosynthesis. Additional studies focused on elucidating a possible role for FlhF in σ54-dependent flagellar gene expression were conducted. These studies revealed that FlhF does not influence production of or signaling between the flagellar export apparatus and the FlgSR two-component regulatory system to activate σ54. Instead, our data suggest that FlhF functions in an independent pathway that converges with or works downstream of the flagellar export apparatus-FlgSR pathway to influence σ54-dependent gene expression. This study provides corroborative biochemical and genetic analyses suggesting that different activities of the C. jejuni FlhF GTPase are required for distinct steps in flagellar gene expression and biosynthesis. Our findings are likely applicable to many polarly flagellated bacteria that utilize FlhF in flagellar biosynthesis processes.

scholarly journals Progress Overview of Bacterial Two-Component Regulatory Systems as Potential Targets for Antimicrobial Chemotherapy

Antibiotics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 635
Author(s):  
Hidetada Hirakawa ◽  
Jun Kurushima ◽  
Yusuke Hashimoto ◽  
Haruyoshi Tomita
Keyword(s):  
Drug Resistance ◽  
Antimicrobial Chemotherapy ◽  
Response Regulator ◽  
Regulatory System ◽  
Laboratory Strain ◽  
Regulatory Systems ◽  
Two Component ◽  
Bacterial Genes ◽  
Conventional Antibiotics ◽  
External Stimuli

Bacteria adapt to changes in their environment using a mechanism known as the two-component regulatory system (TCS) (also called “two-component signal transduction system” or “two-component system”). It comprises a pair of at least two proteins, namely the sensor kinase and the response regulator. The former senses external stimuli while the latter alters the expression profile of bacterial genes for survival and adaptation. Although the first TCS was discovered and characterized in a non-pathogenic laboratory strain of Escherichia coli, it has been recognized that all bacteria, including pathogens, use this mechanism. Some TCSs are essential for cell growth and fitness, while others are associated with the induction of virulence and drug resistance/tolerance. Therefore, the TCS is proposed as a potential target for antimicrobial chemotherapy. This concept is based on the inhibition of bacterial growth with the substances acting like conventional antibiotics in some cases. Alternatively, TCS targeting may reduce the burden of bacterial virulence and drug resistance/tolerance, without causing cell death. Therefore, this approach may aid in the development of antimicrobial therapeutic strategies for refractory infections caused by multi-drug resistant (MDR) pathogens. Herein, we review the progress of TCS inhibitors based on natural and synthetic compounds.

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 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 Regulation of Virulence by a Two-Component System in Group B Streptococcus

2005 ◽  
Vol 187 (3) ◽  
pp. 1105-1113 ◽  
Author(s):  
Sheng-Mei Jiang ◽  
Michael J. Cieslewicz ◽  
Dennis L. Kasper ◽  
Michael R. Wessels
Keyword(s):  
Response Regulator ◽  
Newborn Infants ◽  
Regulatory System ◽  
Virulence Determinants ◽  
Wild Type ◽  
Two Component System ◽  
Component System ◽  
Two Component ◽  
Mutant Strains ◽  
Group B

ABSTRACT Group B Streptococcus (GBS) is frequently carried in the gastrointestinal or genitourinary tract as a commensal organism, yet it has the potential to cause life-threatening infection in newborn infants, pregnant women, and individuals with chronic illness. Regulation of virulence factor expression may affect whether GBS behaves as an asymptomatic colonizer or an invasive pathogen, but little is known about how such factors are controlled in GBS. We now report the characterization of a GBS locus that encodes a two-component regulatory system similar to CsrRS (or CovRS) in Streptococcus pyogenes. Inactivation of csrR, encoding the putative response regulator, in two unrelated wild-type strains of GBS resulted in a marked increase in production of beta-hemolysin/cytolysin and a striking decrease in production of CAMP factor, an unrelated cytolytic toxin. Quantitative RNA hybridization experiments revealed that these two phenotypes were associated with a marked increase and decrease in expression of the corresponding genes, cylE and cfb, respectively. The CsrR mutant strains also displayed increased expression of scpB encoding C5a peptidase. Similar, but less marked, changes in gene expression were observed in CsrS (putative sensor component) mutants, evidence that CsrR and CsrS constitute a functional two-component system. Experimental infection studies in mice demonstrated reduced virulence of both CsrR and CsrS mutant strains relative to the wild type. Together, these results indicate that CsrRS regulates expression of multiple GBS virulence determinants and is likely to play an important role in GBS pathogenesis.

scholarly journals Mutations Affecting HVO_1357 or HVO_2248 Cause Hypermotility in Haloferax volcanii, Suggesting Roles in Motility Regulation

Genes ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 58
Author(s):  
Michiyah Collins ◽  
Simisola Afolayan ◽  
Aime B. Igiraneza ◽  
Heather Schiller ◽  
Elise Krespan ◽  
...  
Keyword(s):  
Histidine Kinase ◽  
Response Regulator ◽  
Regulatory System ◽  
Haloferax Volcanii ◽  
Adjacent Gene ◽  
Transposon Insertion ◽  
Regulatory Systems ◽  
Two Component ◽  
Motility Regulation ◽  
Transposon Insertions

Motility regulation plays a key role in prokaryotic responses to environmental stimuli. Here, we used a motility screen and selection to isolate hypermotile Haloferax volcanii mutants from a transposon insertion library. Whole genome sequencing revealed that hypermotile mutants were predominantly affected in two genes that encode HVO_1357 and HVO_2248. Alterations of these genes comprised not only transposon insertions but also secondary genome alterations. HVO_1357 contains a domain that was previously identified in the regulation of bacteriorhodopsin transcription, as well as other domains frequently found in two-component regulatory systems. The genes adjacent to hvo_1357 encode a sensor box histidine kinase and a response regulator, key players of a two-component regulatory system. None of the homologues of HVO_2248 have been characterized, nor does it contain any of the assigned InterPro domains. However, in a significant number of Haloferax species, the adjacent gene codes for a chemotaxis receptor/transducer. Our results provide a foundation for characterizing the root causes underlying Hfx. volcanii hypermotility.

scholarly journals Activated by Different Signals, the PhoP/PhoQ Two-Component System Differentially Regulates Metal Uptake

2009 ◽  
Vol 191 (23) ◽  
pp. 7174-7181 ◽  
Author(s):  
Eunna Choi ◽  
Eduardo A. Groisman ◽  
Dongwoo Shin
Keyword(s):  
Metal Uptake ◽  
Response Regulator ◽  
Regulatory System ◽  
Acidic Ph ◽  
Transporter Gene ◽  
Coding Region ◽  
Two Component System ◽  
Component System ◽  
Input Signals ◽  
Two Component

ABSTRACT The PhoP/PhoQ two-component system controls several physiological and virulence functions in Salmonella enterica. This system is activated by low Mg2+, acidic pH, and antimicrobial peptides, but the biological consequences resulting from sensing multiple signals are presently unclear. Here, we report that the PhoP/PhoQ system regulates different Salmonella genes depending on whether the inducing signal is acidic pH or low Mg2+. When Salmonella experiences acidic pH, the PhoP/PhoQ system promotes Fe2+ uptake in a process that requires the response regulator RstA, activating transcription of the Fe2+ transporter gene feoB. In contrast, the PhoP-induced RstA protein did not promote feoB expression at neutral pH with low Mg2+. The PhoP/PhoQ system promotes the expression of the Mg2+ transporter mgtA gene only when activated in bacteria starved for Mg2+. This is because mgtA transcription promoted at high Mg2+ concentrations by the acidic-pH-activated PhoP protein failed to reach the mgtA coding region due to the mgtA leader region functioning as a Mg2+ sensor. Our results show that a single two-component regulatory system can regulate distinct sets of genes in response to different input signals.

DevR–DevS is a bona fide two-component system of Mycobacterium tuberculosis that is hypoxia-responsive in the absence of the DNA-binding domain of DevR

Microbiology ◽  
2004 ◽  
Vol 150 (4) ◽  
pp. 865-875 ◽  
Author(s):  
Deepak Kumar Saini ◽  
Vandana Malhotra ◽  
Deepanwita Dey ◽  
Neha Pant ◽  
Taposh K. Das ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Pathogenic Bacteria ◽  
Response Regulator ◽  
Regulatory System ◽  
Site Directed Mutagenesis ◽  
Phosphoryl Transfer ◽  
Dependent Manner ◽  
Two Component System ◽  
Component System ◽  
Two Component

Two-component systems play a central role in the adaptation of pathogenic bacteria to the environment prevailing within host tissues. The genes encoding the response regulator DevR (Rv3133c/DosR) and the cytoplasmic portion (DevS201) of the histidine kinase DevS (Rv3132c/DosS), a putative two-component system of Mycobacterium tuberculosis, were cloned and the protein products were overexpressed, purified and refolded as N-terminally His6-tagged proteins from Escherichia coli. DevS201 underwent autophosphorylation and participated in rapid phosphotransfer to DevR in a Mg2+-dependent manner. Chemical stability analysis and site-directed mutagenesis implicated the highly conserved residues His395 and Asp54 as the sites of phosphorylation in DevS and DevR, respectively. Mutations in Asp8 and Asp9 residues, postulated to form the acidic Mg2+-binding pocket, and the invariant Lys104 of DevR, abrogated phosphoryl transfer from DevS201 to DevR. DevR–DevS was thus established as a typical two-component regulatory system based on His-to-Asp phosphoryl transfer. Expression of the Rv3134c–devR–devS operon was induced at the RNA level in hypoxic cultures of M. tuberculosis H37Rv and was associated with an increase in the level of DevR protein. However, in a devR mutant strain expressing the N-terminal domain of DevR, induction was observed at the level of RNA expression but not at that of protein. DevS was translated independently of DevR and induction of devS transcripts was not associated with an increase in protein level in either wild-type or mutant strains, reflecting differential regulation of this locus during hypoxia.

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