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 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 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 Localization and Cellular Amounts of the WalRKJ (VicRKX) Two-Component Regulatory System Proteins in Serotype 2 Streptococcus pneumoniae

2010 ◽  
Vol 192 (17) ◽  
pp. 4388-4394 ◽  
Author(s):  
Kyle J. Wayne ◽  
Lok-To Sham ◽  
Ho-Ching T. Tsui ◽  
Alina D. Gutu ◽  
Skye M. Barendt ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Histidine Kinase ◽  
Cellular Localization ◽  
Immunofluorescence Microscopy ◽  
Response Regulator ◽  
Regulatory System ◽  
Respiratory Pathogen ◽  
Cell Periphery ◽  
Gram Positive Bacteria ◽  
Two Component

ABSTRACT The WalRK two-component regulatory system coordinates gene expression that maintains cell wall homeostasis and responds to antibiotic stress in low-GC Gram-positive bacteria. Phosphorylated WalR (VicR) of the major human respiratory pathogen Streptococcus pneumoniae (WalR Spn ) positively regulates transcription of several surface virulence genes and, most critically, pcsB, which encodes an essential cell division protein. Despite numerous studies of several species, little is known about the signals sensed by the WalK histidine kinase or the function of the WalJ ancillary protein encoded in the walRKSpn operon. To better understand the functions of the WalRKJ Spn proteins in S. pneumoniae, we performed experiments to determine their cellular localization and amounts. In contrast to WalK from Bacillus subtilis (WalK Bsu ), which is localized at division septa, immunofluorescence microscopy showed that WalK Spn is distributed throughout the cell periphery. WalJ Spn is also localized to the cell surface periphery, whereas WalR Spn was found to be localized in the cytoplasm around the nucleoid. In fractionation experiments, WalR Spn was recovered from the cytoplasmic fraction, while WalK Spn and the majority of WalJ Spn were recovered from the cell membrane fraction. This fractionation is consistent with the localization patterns observed. Lastly, we determined the cellular amounts of WalRKJ Spn by quantitative Western blotting. The WalR Spn response regulator is relatively abundant and present at levels of ≈6,200 monomers per cell, which are ≈14-fold greater than the amount of the WalK Spn histidine kinase, which is present at ≈460 dimers (920 monomers) per cell. We detected ≈1,200 monomers per cell of WalJ Spn ancillary protein, similar to the amount of WalK Spn .

scholarly journals Fumarate Regulation of Gene Expression in Escherichia coli by the DcuSR (dcuSR Genes) Two-Component Regulatory System

1998 ◽  
Vol 180 (20) ◽  
pp. 5421-5425 ◽  
Author(s):  
Evelyn Zientz ◽  
Johannes Bongaerts ◽  
Gottfried Unden
Keyword(s):  
Escherichia Coli ◽  
Histidine Kinase ◽  
Response Regulator ◽  
Regulation Of Gene Expression ◽  
Regulatory System ◽  
E Coli ◽  
Expression In Escherichia Coli ◽  
Two Component ◽  
Genes Encoding ◽  
Periplasmic Domain

ABSTRACT In Escherichia coli the genes encoding the anaerobic fumarate respiratory system are transcriptionally regulated by C4-dicarboxylates. The regulation is effected by a two-component regulatory system, DcuSR, consisting of a sensory histidine kinase (DcuS) and a response regulator (DcuR). DcuS and DcuR are encoded by the dcuSR genes (previouslyyjdHG) at 93.7 min on the calculated E. coli map. Inactivation of the dcuR anddcuS genes caused the loss of C4-dicarboxylate-stimulated synthesis of fumarate reductase (frdABCD genes) and of the anaerobic fumarate-succinate antiporter DcuB (dcuB gene). DcuS is predicted to contain a large periplasmic domain as the supposed site for C4-dicarboxylate sensing. Regulation by DcuR and DcuS responded to the presence of the C4-dicarboxylates fumarate, succinate, malate, aspartate, tartrate, and maleate. Since maleate is not taken up by the bacteria under these conditions, the carboxylates presumably act from without. Genes of the aerobic C4-dicarboxylate pathway encoding succinate dehydrogenase (sdhCDAB) and the aerobic succinate carrier (dctA) are only marginally or negatively regulated by the DcuSR system. The CitAB two-component regulatory system, which is highly similar to DcuSR, had no effect on C4-dicarboxylate regulation of any of the genes.

scholarly journals The Cpx Envelope Stress Response Is Controlled by Amplification and Feedback Inhibition

1999 ◽  
Vol 181 (17) ◽  
pp. 5263-5272 ◽  
Author(s):  
Tracy L. Raivio ◽  
Daniel L. Popkin ◽  
Thomas J. Silhavy
Keyword(s):  
Escherichia Coli ◽  
Stress Response ◽  
Virulence Factors ◽  
Histidine Kinase ◽  
Feedback Inhibition ◽  
Response Regulator ◽  
Regulatory System ◽  
Concomitant Increase ◽  
Envelope Stress ◽  
Two Component

ABSTRACT In Escherichia coli, the Cpx two-component regulatory system activates expression of protein folding and degrading factors in response to misfolded proteins in the bacterial envelope (inner membrane, periplasm, and outer membrane). It is comprised of the histidine kinase CpxA and the response regulator CpxR. This response plays a role in protection from stresses, such as elevated pH, as well as in the biogenesis of virulence factors. Here, we show that the Cpx periplasmic stress response is subject to amplification and repression through positive and negative autofeedback mechanisms. Western blot and operon fusion analyses demonstrated that the cpxRA operon is autoactivated. Conditions that lead to elevated levels of phosphorylated CpxR cause a concomitant increase in transcription ofcpxRA. Conversely, overproduction of CpxP, a small, Cpx-regulated protein of previously unknown function, represses the regulon and can block activation of the pathway. This repression is dependent on an intact CpxA sensing domain. The ability to autoactivate and then subsequently repress allows for a temporary amplification of the Cpx response that may be important in rescuing cells from transitory stresses and cueing the appropriately timed elaboration of virulence factors.

scholarly journals Succinoglycan Production by Rhizobium meliloti Is Regulated through the ExoS-ChvI Two-Component Regulatory System

1998 ◽  
Vol 180 (1) ◽  
pp. 20-26 ◽  
Author(s):  
Hai-Ping Cheng ◽  
Graham C. Walker
Keyword(s):  
Histidine Kinase ◽  
Cytoplasmic Membrane ◽  
Rhizobium Meliloti ◽  
Response Regulator ◽  
Regulatory System ◽  
Kinase Domain ◽  
Cloning And Sequencing ◽  
System A ◽  
Two Component ◽  
Close Homolog

ABSTRACT The Rhizobium meliloti exoS gene is involved in regulating the production of succinoglycan, which plays a crucial role in the establishment of the symbiosis between R. melilotiRm1021 and its host plant, alfalfa. TheexoS96::Tn5 mutation causes the upregulation of the succinoglycan biosynthetic genes, thereby resulting in the overproduction of succinoglycan. Through cloning and sequencing, we found that the exoS gene is a close homolog of theAgrobacterium tumefaciens chvG gene, which has been proposed to encode the sensor protein of the ChvG-ChvI two-component regulatory system, a member of the EnvZ-OmpR family. Further analyses revealed the existence of a newly discovered A. tumefaciens chvI homolog located just upstream of the R. meliloti exoS gene. R. meliloti ChvI may serve as the response regulator of ExoS in a two-component regulatory system. By using ExoS-specific antibodies, it was found that the ExoS protein cofractionated with membrane proteins, suggesting that it is located in the cytoplasmic membrane. By using the same antibodies, it was shown that the exoS96::Tn5 allele encodes an N-terminal truncated derivative of ExoS. The cytoplasmic histidine kinase domain of ExoS was expressed in Escherichia coli and purified, as was the R. meliloti ChvI protein. The ChvI protein autophosphorylated in the presence of acetylphosphate, and the ExoS cytoplasmic domain fragment autophosphorylated at a histidine residue in the presence of ATP. The ChvI protein was phosphorylated in the presence of ATP only when the histidine kinase domain of ExoS was also present. We propose a model for regulation of succinoglycan production by R. meliloti through the ExoS-ChvI two-component regulatory system.

scholarly journals Novel two-component regulatory systems play a role in biofilm formation of Lactobacillus reuteri rodent isolate 100-23

Microbiology ◽  
2014 ◽  
Vol 160 (4) ◽  
pp. 795-806 ◽  
Author(s):  
Marcia Shu-Wei Su ◽  
Michael G. Gänzle
Keyword(s):  
Histidine Kinase ◽  
Biofilm Formation ◽  
Lactobacillus Reuteri ◽  
Response Regulator ◽  
Multiple Genes ◽  
Regulatory Systems ◽  
Two Component ◽  
Two Component Systems ◽  
Processing Peptidase

This study characterized the two-component regulatory systems encoded by bfrKRT and cemAKR, and assessed their influence on biofilm formation by Lactobacillus reuteri 100-23. A method for deletion of multiple genes was employed to disrupt the genetic loci of two-component systems. The operons bfrKRT and cemAKR showed complementary organization. Genes bfrKRT encode a histidine kinase, a response regulator and an ATP-binding cassette-type transporter with a bacteriocin-processing peptidase domain, respectively. Genes cemAKR code for a signal peptide, a histidine kinase and a response regulator, respectively. Deletion of single or multiple genes in the operons bfrKRT and cemAKR did not affect cell morphology, growth or the sensitivity to various stressors. However, gene disruption affected biofilm formation; this effect was dependent on the carbon source. Deletion of bfrK or cemA increased sucrose-dependent biofilm formation in vitro. Glucose-dependent biofilm formation was particularly increased by deletion of cemK. The expression of cemK and cemR was altered by deletion of bfrK, indicating cross-talk between these two regulatory systems. These results may contribute to our understanding of the genetic factors related to the biofilm formation and competitiveness of L. reuteri in intestinal ecosystems.

scholarly journals Analysis of the Activity and Regulon of the Two-Component Regulatory System Composed by Cjj81176_1484 and Cjj81176_1483 of Campylobacter jejuni

2015 ◽  
Vol 197 (9) ◽  
pp. 1592-1605 ◽  
Author(s):  
Paul M. Luethy ◽  
Steven Huynh ◽  
Craig T. Parker ◽  
David R. Hendrixson
Keyword(s):  
Campylobacter Jejuni ◽  
Histidine Kinase ◽  
Intestinal Tract ◽  
Diarrheal Disease ◽  
Response Regulator ◽  
Optimal Growth ◽  
Content Type ◽  
Regulatory Systems ◽  
Two Component ◽  
Genes Encoding

ABSTRACTCampylobacter jejuniis a leading cause of bacterial diarrheal disease and a frequent commensal of the intestinal tract in poultry and other animals. For optimal growth and colonization of hosts,C. jejuniemploys two-component regulatory systems (TCSs) to monitor environmental conditions and promote proper expression of specific genes. We analyzed the potential ofC. jejuniCjj81176_1484(Cjj1484) andCjj81176_1483(Cjj1483) to encode proteins of a cognate TCS that influences expression of genes possibly important forC. jejunigrowth and colonization. Transcriptome analysis revealed that the regulons of the Cjj81176_1484 (Cjj1484) histidine kinase and the Cjj81176_1483 (Cjj1483) response regulator contain many common genes, suggesting that these proteins likely form a cognate TCS. We found that this TCS generally functions to repress expression of specific proteins with roles in metabolism, iron/heme acquisition, and respiration. Furthermore, the TCS repressed expression ofCjj81176_0438andCjj81176_0439, which had previously been found to encode a gluconate dehydrogenase complex required for commensal colonization of the chick intestinal tract. However, the TCS and other specific genes whose expression is repressed by the TCS were not required for colonization of chicks. We observed that the Cjj1483 response regulator binds target promoters in both unphosphorylated and phosphorylated forms and influences expression of some specific genes independently of the Cjj1484 histidine kinase. This work further expands the signaling mechanisms ofC. jejuniand provides additional insights regarding the complex and multifactorial regulation of many genes involved in basic metabolism, respiration, and nutrient acquisition that the bacterium requires for optimal growth in different environments.IMPORTANCEBacterial two-component regulatory systems (TCSs) link environmental cues to expression of specific genes that enable optimal bacterial growth or colonization of hosts. We found that theCampylobacter jejuniCjj1484 histidine kinase and Cjj1483 response regulator function as a cognate TCS to largely repress expression of target genes encoding a gluconate dehydrogenase complex required for commensal colonization of the chick intestinal tract, as well as other genes encoding proteins for heme or iron acquisition, metabolism, and respiration. We also discovered different modes by which Cjj1483 may mediate repression with and without Cjj1484. This work provides insight into the signal transduction mechanisms of a leading cause of bacterial diarrheal disease and emphasizes the multifactorial and complex regulation of specific biological processes inC. jejuni.

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.

Bacteriocin production in Streptococcus gallolyticus is controlled by a complex 4-component regulatory system with activator and anti-activator activities

2020 ◽  
Author(s):  
Alexis Proutière ◽  
Bruno Périchon ◽  
Laurence du Merle ◽  
Hugo Varet ◽  
Patrick Trieu-Cuot ◽  
...  
Keyword(s):  
Histidine Kinase ◽  
Response Regulator ◽  
Regulatory System ◽  
Opportunistic Pathogen ◽  
Bacteriocin Production ◽  
Two Component System ◽  
Promoter Regions ◽  
Component System ◽  
Streptococcus Gallolyticus ◽  
Two Component

AbstractBacteriocins are natural antimicrobial peptides produced by bacteria to kill closely related competitors. The opportunistic pathogen Streptococcus gallolyticus (Sgg) was recently shown to outcompete commensal enterococci of the murine microbiota in tumoral conditions thanks to the production of a two-peptide bacteriocin named gallocin. We here identified 4 genes involved in the regulatory control of gallocin in Sgg UCN34, respectively encoding a histidine kinase/response regulator two-component system (BlpH/BlpR), a secreted peptide (GSP), and a putative regulator of unknown function (BlpS). While BlpR is a typical 243-aa response regulator possessing a phospho-receiver domain and a LytTR DNA-binding domain, BlpS is a 108-aa protein containing only a LytTR domain. Our results showed that the secreted peptide GSP activates the dedicated two-component system BlpH/BlpR to induce gallocin transcription. A genome-wide transcriptome analysis indicates that this regulatory system (GSP-BlpH/BlpR) is highly specific for bacteriocin production. Importantly, as opposed to BlpR, BlpS was shown to repress gallocin gene transcription. A conserved operator DNA sequence of 30-bp was found in all promoter regions regulated by BlpR and BlpS. EMSA assays showed direct and specific binding of the two gallocin regulators to various regulated promoter regions in a dose dependent manner. Gallocin expression appears tightly controlled in Sgg by quorum sensing and antagonistic activity of 2 LytTR-containing proteins.SignificanceStreptococcus gallolyticus (Sgg), formely known as S. bovis biotype I, is an opportunistic pathogen causing septicemia and endocarditis in the elderly often associated with asymptomatic colonic neoplasia. We previously showed that Sgg produces a bacteriocin, termed gallocin, enabling colonization of the colon in tumoral conditions by outcompeting commensal members of the gut. Here we characterized a 4-component regulatory system that regulates gallocin transcription, which is activated by the response regulator BlpR. BlpR itself is activated by a quorum sensing peptide GSP and a dedicated histidine kinase BlpH. Interestingly, BlpS, a small DNA-binding protein co-transcribed with BlpR was found to repress gallocin genes transcription, likely by antagonizing BlpR. Understanding gallocin regulation is crucial to prevent Sgg colon colonization in tumoral conditions.

Sign in / Sign up

Export Citation Format

Share Document