scholarly journals Inhibition of competence development in Streptococcus pneumoniae by increased basal-level expression of the ComDE two-component regulatory system

Microbiology ◽  
2006 ◽  
Vol 152 (2) ◽  
pp. 323-331 ◽  
Author(s):  
Sébastien Guiral ◽  
Vincent Hénard ◽  
Chantal Granadel ◽  
Bernard Martin ◽  
Jean-Pierre Claverys
Keyword(s):  
Streptococcus Pneumoniae ◽  
Response Regulator ◽  
Signal Transduction Pathway ◽  
Regulatory System ◽  
Competence Development ◽  
Critical Threshold ◽  
Transcription Terminator ◽  
Two Component ◽  
Cognate Response Regulator ◽  
Basal Level Expression

Natural competence for genetic transformation in Streptococcus pneumoniae is controlled by the ComCDE signal-transduction pathway. Together, ComD, a membrane histidine kinase, and ComE, its cognate response regulator, constitute a typical two-component regulatory system involved in sensing the comC-encoded competence-stimulating peptide (CSP). The comCDE operon is strongly upregulated when CSP reaches a critical threshold, probably to coordinate competence induction throughout the population. During a study of the early regulation of the comCDE operon, a mutation which resulted in increased β-galactosidase production from a comC : : lacZ fusion was isolated. This mutation, which was characterized as a G→T change in the transcription terminator of the tRNAArg located immediately upstream of comCDE, is suggested to destabilize the terminator and to allow transcriptional readthrough of comCDE. Here, it is shown that, quite unexpectedly, the mutation confers reduced transformability. A series of experiments undertaken with the aim of understanding this surprising phenotype is described. Evidence is presented that increased basal-level expression of comDE impedes both spontaneous and CSP-induced competence in S. pneumoniae. There is a discussion of how an increased concentration of ComD and/or ComE could affect competence development.

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 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 Exposure of a 23F Serotype Strain ofStreptococcus pneumoniaeto Cigarette Smoke Condensate Is Associated with Selective Upregulation of Genes Encoding the Two-Component Regulatory System 11 (TCS11)

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
Riana Cockeran ◽  
Jenny A. Herbert ◽  
Timothy J. Mitchell ◽  
Thérèse Dix-Peek ◽  
Caroline Dickens ◽  
...  
Keyword(s):  
Cigarette Smoke ◽  
Response Regulator ◽  
Expression Profiles ◽  
Regulatory System ◽  
Cigarette Smoke Condensate ◽  
Genome Expression ◽  
Two Component ◽  
Genes Encoding ◽  
Whole Genome Expression ◽  
Cognate Response Regulator

Alterations in whole genome expression profiles following exposure of the pneumococcus (strain 172, serotype 23F) to cigarette smoke condensate (160 μg/mL) for 15 and 60 min have been determined using the TIGR4 DNA microarray chip. Exposure to CSC resulted in the significant (P<0.014–0.0006) upregulation of the genes encoding the two-component regulatory system 11 (TCS11), consisting of the sensor kinase,hk11, and its cognate response regulator,rr11, in the setting of increased biofilm formation. These effects of cigarette smoke on the pneumococcus may contribute to colonization of the airways by this microbial pathogen.

scholarly journals Effect of new alleles of the histidine kinase gene ciaH on the activity of the response regulator CiaR in Streptococcus pneumoniae R6

Microbiology ◽  
2011 ◽  
Vol 157 (11) ◽  
pp. 3104-3112 ◽  
Author(s):  
Miriam Müller ◽  
Patrick Marx ◽  
Regine Hakenbeck ◽  
Reinhold Brückner
Keyword(s):  
Streptococcus Pneumoniae ◽  
Histidine Kinase ◽  
Response Regulator ◽  
Regulatory System ◽  
Competence Development ◽  
Kinase Gene ◽  
Lactam Antibiotic ◽  
Spontaneous Mutants ◽  
New Alleles

The two-component regulatory system CiaRH of Streptococcus pneumoniae affects β-lactam susceptibility, autolysis, bacteriocin production, competence development, host colonization and virulence. The system was discovered in a screen for S. pneumoniae R6 mutants resistant to the β-lactam antibiotic cefotaxime. A mutation in the histidine kinase gene ciaH led to this phenotype by enhancing CiaR-mediated gene expression. Additional mutations in ciaH have been described in other spontaneous β-lactam-resistant mutants of S. pneumoniae R6, but their influence on CiaR-mediated gene regulation has not been determined. Likewise, altered ciaH alleles are present in clinical S. pneumoniae isolates, none of which had been characterized. These novel ciaH variants were introduced into S. pneumoniae R6 to measure their ability to activate CiaR-dependent regulation. The ciaH alleles from spontaneous mutants obtained in the laboratory increased the activity of CiaR-dependent promoters between four- and 26-fold, while variants from clinical strains were less effective, with a threefold activation at most. Accordingly, phenotypes associated with a hyperactive CiaRH system, β-lactam resistance, and prevention of competence development, were far more pronounced in the laboratory mutants. Amino acid changes affecting CiaH function were positioned throughout the protein. Five of the most activating changes are located close to the conserved histidine and one in the extracytoplasmic sensor domain. The characterization of new alleles of ciaH expands the spectrum of CiaH variants, which may help to elucidate signal transduction of this important regulatory system. Our study also demonstrates that ciaH alleles overstimulating CiaR regulon expression are present in clinical isolates of S. pneumoniae.

scholarly journals Identification of cpxR as a Positive Regulator Essential for Expression of the Shigella sonnei virF Gene

1998 ◽  
Vol 180 (14) ◽  
pp. 3522-3528 ◽  
Author(s):  
Shu-ichi Nakayama ◽  
Haruo Watanabe
Keyword(s):  
Response Regulator ◽  
Binding Capacity ◽  
Regulatory System ◽  
Upstream Region ◽  
Dependent Manner ◽  
Acetyl Phosphate ◽  
Two Component ◽  
Transcription In Vitro ◽  
Cognate Response Regulator

ABSTRACT virF is the master regulator which activates the virulence determinant genes of Shigella spp. such asipaBCD and virG. We previously reported that expression of virF itself is regulated in a pH-dependent manner and that cpxA, a sensor of a two-component regulatory system, is involved in this regulation (S. Nakayama and H. Watanabe, J. Bacteriol. 177:5062–5069, 1995). Disruption of cpxR, which has been thought to be the cognate response regulator of cpxA (J. Dong, S. Iuchi, H.-S. Kwan, Z. Lue, and E. C. C. Lin, Gene 136:227–230, 1993), abolishedvirF expression almost completely. Purified CpxR bound directly to the upstream region of virF. Binding capacity was enhanced when CpxR was phosphorylated by coincubation with acetyl phosphate in vitro. Furthermore, we observed that phosphorylated CpxR could activate virF transcription in vitro. These results clearly indicated that CpxR was an essential activator for virF expression and strongly suggested that the binding of phosphorylated CpxR to the target site upstream of the virF gene induced a direct activation of virF transcription.

AgmR controls transcription of a regulon with several operons essential for ethanol oxidation in Pseudomonas aeruginosa ATCC 17933

Microbiology ◽  
2004 ◽  
Vol 150 (6) ◽  
pp. 1851-1857 ◽  
Author(s):  
Nicole Gliese ◽  
Viola Khodaverdi ◽  
Max Schobert ◽  
Helmut Görisch
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Ethanol Oxidation ◽  
Response Regulator ◽  
Regulatory System ◽  
Pyrroloquinoline Quinone ◽  
Kanamycin Resistance ◽  
Kanamycin Resistance Cassette ◽  
Two Component ◽  
Ethanol Dehydrogenase ◽  
Oxidation System

The response regulator AgmR was identified to be involved in the regulation of the quinoprotein ethanol oxidation system of Pseudomonas aeruginosa ATCC 17933. Interruption of the agmR gene by insertion of a kanamycin-resistance cassette resulted in mutant NG3, unable to grow on ethanol. After complementation with the intact agmR gene, growth on ethanol was restored. Transcriptional lacZ fusions were used to identify four operons which are regulated by the AgmR protein: the exaA operon encodes the pyrroloquinoline quinone (PQQ)-dependent ethanol dehydrogenase, the exaBC operon encodes a soluble cytochrome c 550 and an aldehyde dehydrogenase, the pqqABCDE operon carries the PQQ biosynthetic genes, and operon exaDE encodes a two-component regulatory system which controls transcription of the exaA operon. Transcription of exaA was restored by transformation of NG3 with a pUCP20T derivative carrying the exaDE genes under lac-promoter control. These data indicate that the AgmR response regulator and the exaDE two-component regulatory system are organized in a hierarchical manner. Gene PA1977, which appears to form an operon with the agmR gene, was found to be non-essential for growth on ethanol.

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 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 Analysis of a Growth-Phase-Regulated Two-Component Regulatory System in the Periodontal Pathogen Treponema denticola

2008 ◽  
Vol 190 (18) ◽  
pp. 6162-6169 ◽  
Author(s):  
Jesse R. Frederick ◽  
Elizabeth A. Rogers ◽  
Richard T. Marconi
Keyword(s):  
Growth Phase ◽  
Regulatory Networks ◽  
Response Regulator ◽  
Regulatory System ◽  
Open Reading Frames ◽  
Periodontal Pathogen ◽  
Treponema Denticola ◽  
Rt Pcr ◽  
Two Component ◽  
Transcriptional Regulatory Mechanisms

ABSTRACT Nothing is currently known regarding the global regulatory networks of Treponema denticola and other oral spirochetes. In this report, we assess the properties and potential phosphotransfer capability of a putative two-component regulatory system (TCS) of T. denticola that is formed by the products of open reading frames tde0032 (a sensor kinase) and tde0033 (a response regulator), henceforth designated AtcS and AtcR, respectively. Using PCR and DNA sequence analyses, atcS and atcR were demonstrated to be widely distributed and conserved among T. denticola isolates. Reverse transcription-PCR (RT-PCR) analyses revealed that these genes are cotranscribed and may also be expressed as part of a larger operon that includes several flanking genes. Analyses using 5′ rapid amplification of cDNA ends identified the transcriptional start sites for these operons and provided evidence that some of these genes may be independently transcribed from internal promoters. Real-time RT-PCR and Western blot analysis revealed significant upregulation of atcRS during late-stage growth, indicating growth-phase-dependent expression. Lastly, the phosphorelay capability of the AtcRS system was assessed and demonstrated using recombinant proteins. AtcS was found to undergo autophosphorylation and to transfer phosphate to AtcR. These analyses represent the first description of a functional TCS in an oral spirochetes and provide insight into the transcriptional regulatory mechanisms of these important bacteria.

scholarly journals RocA Binds CsrS To Modulate CsrRS-Mediated Gene Regulation in Group A Streptococcus

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Nicola N. Lynskey ◽  
Jorge J. Velarde ◽  
Meredith B. Finn ◽  
Simon L. Dove ◽  
Michael R. Wessels
Keyword(s):  
Gene Regulation ◽  
Target Genes ◽  
Response Regulator ◽  
Critical Role ◽  
Regulatory Protein ◽  
Regulatory System ◽  
Fine Tuning ◽  
Human Pathogen ◽  
Two Component ◽  
Group A

ABSTRACT The orphan regulator RocA plays a critical role in the colonization and pathogenesis of the obligate human pathogen group A Streptococcus. Despite multiple lines of evidence supporting a role for RocA as an auxiliary regulator of the control of virulence two-component regulatory system CsrRS (or CovRS), the mechanism of action of RocA remains unknown. Using a combination of in vitro and in vivo techniques, we now find that RocA interacts with CsrS in the streptococcal membrane via its N-terminal region, which contains seven transmembrane domains. This interaction is essential for RocA-mediated regulation of CsrRS function. Furthermore, we demonstrate that RocA forms homodimers via its cytoplasmic domain. The serotype-specific RocA truncation in M3 isolates alters this homotypic interaction, resulting in protein aggregation and impairment of RocA-mediated regulation. Taken together, our findings provide insight into the molecular requirements for functional interaction of RocA with CsrS to modulate CsrRS-mediated gene regulation. IMPORTANCE Bacterial two-component regulatory systems, comprising a membrane-bound sensor kinase and cytosolic response regulator, are critical in coordinating the bacterial response to changing environmental conditions. More recently, auxiliary regulators which act to modulate the activity of two-component systems, allowing integration of multiple signals and fine-tuning of bacterial responses, have been identified. RocA is a regulatory protein encoded by all serotypes of the important human pathogen group A Streptococcus. Although RocA is known to exert its regulatory activity via the streptococcal two-component regulatory system CsrRS, the mechanism by which it functions was unknown. Based on new experimental evidence, we propose a model whereby RocA interacts with CsrS in the streptococcal cell membrane to enhance CsrS autokinase activity and subsequent phosphotransfer to the response regulator CsrR, which mediates transcriptional repression of target genes.

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