scholarly journals ZraP is a periplasmic molecular chaperone and a repressor of the zinc-responsive two-component regulator ZraSR

2012 ◽  
Vol 442 (1) ◽  
pp. 85-93 ◽  
Author(s):  
Corinne Appia-Ayme ◽  
Andrea Hall ◽  
Elaine Patrick ◽  
Shiny Rajadurai ◽  
Thomas A. Clarke ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Regulatory System ◽  
Enteric Bacteria ◽  
Polymyxin B ◽  
Regulatory Function ◽  
Cationic Antimicrobial Peptide ◽  
Envelope Stress ◽  
Two Component ◽  
Periplasmic Proteins ◽  
Zinc Concentrations

The bacterial envelope is the interface with the surrounding environment and is consequently subjected to a barrage of noxious agents including a range of compounds with antimicrobial activity. The ESR (envelope stress response) pathways of enteric bacteria are critical for maintenance of the envelope against these antimicrobial agents. In the present study, we demonstrate that the periplasmic protein ZraP contributes to envelope homoeostasis and assign both chaperone and regulatory function to ZraP from Salmonella Typhimurium. The ZraP chaperone mechanism is catalytic and independent of ATP; the chaperone activity is dependent on the presence of zinc, which is shown to be responsible for the stabilization of an oligomeric ZraP complex. Furthermore, ZraP can act to repress the two-component regulatory system ZraSR, which itself is responsive to zinc concentrations. Through structural homology, ZraP is a member of the bacterial CpxP family of periplasmic proteins, which also consists of CpxP and Spy. We demonstrate environmental co-expression of the CpxP family and identify an important role for these proteins in Salmonella's defence against the cationic antimicrobial peptide polymyxin B.

scholarly journals A mutation in the pmrD gene of Shigella flexneri abrogates functional PhoPQ-PmrD-PmrAB signaling and polymyxin B resistance

2021 ◽  
Author(s):  
Joseph B McPhee ◽  
Raymond Huynh
Keyword(s):  
Gene Loss ◽  
Shigella Flexneri ◽  
Regulatory System ◽  
Polymyxin B ◽  
Initiation Site ◽  
Specific Gene ◽  
Gene Gain ◽  
Cationic Antimicrobial Peptide ◽  
Translational Initiation ◽  
Two Component

Shigella spp. are the causative agent of bacillary dysentery, a major cause of food-borne morbidity and mortality worldwide. These organisms are recently evolved, polyphyletic pathovar of E. coli, and since their divergence they have undergone multiple cases of gene gain and gene loss and understanding how gene inactivation events alter bacterial behaviour represents an important objective to be better able to understand how virulence and other phenotypes are affected. Here, we identify a frameshift mutation in the pmrD gene of S. flexneri that although it would be predicted to make a functional, full-length protein, no such production occurs, likely due to the non-optimal spacing between the translational initiation site and the Shine-Dalgarno sequence. We show that this loss severs the normal connection between the PhoPQ two-component regulatory system and the PmrAB two-component regulatory system, abrogating low Mg2+ mediated cationic antimicrobial peptide and polymyxin B resistance, while maintaining normal PmrAB-mediated polymyxin B resistance. In contrast, S. sonnei maintains a functional PmrD protein and canonical signaling through this regulatory network. This species specific gene loss suggests that S. flexneri and S. sonnei have evolved different regulatory responses to changing environmental conditions.

scholarly journals Adaptive Resistance to the “Last Hope” Antibiotics Polymyxin B and Colistin in Pseudomonas aeruginosa Is Mediated by the Novel Two-Component Regulatory System ParR-ParS

2010 ◽  
Vol 54 (8) ◽  
pp. 3372-3382 ◽  
Author(s):  
Lucía Fernández ◽  
W. James Gooderham ◽  
Manjeet Bains ◽  
Joseph B. McPhee ◽  
Irith Wiegand ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Lipid A ◽  
Antimicrobial Agents ◽  
Regulatory System ◽  
Opportunistic Pathogen ◽  
Polymyxin B ◽  
Adaptive Resistance ◽  
Two Component ◽  
Induce Resistance ◽  
Two Component Systems

ABSTRACT As multidrug resistance increases alarmingly, polymyxin B and colistin are increasingly being used in the clinic to treat serious Pseudomonas aeruginosa infections. In this opportunistic pathogen, subinhibitory levels of polymyxins and certain antimicrobial peptides induce resistance toward higher, otherwise lethal, levels of these antimicrobial agents. It is known that the modification of lipid A of lipopolysaccharide (LPS) is a key component of this adaptive peptide resistance, but to date, the regulatory mechanism underlying peptide regulation in P. aeruginosa has remained elusive. The PhoP-PhoQ and PmrA-PmrB two-component systems, which control this modification under low-Mg2+ conditions, do not appear to play a major role in peptide-mediated adaptive resistance, unlike in Salmonella where PhoQ is a peptide sensor. Here we describe the identification and characterization of a novel P. aeruginosa two-component regulator affecting p olymyxin- a daptive r esistance, ParR-ParS (PA1799-PA1798). This system was required for activation of the arnBCADTEF LPS modification operon in the presence of subinhibitory concentrations of polymyxin, colistin, or the bovine peptide indolicidin, leading to increased resistance to various polycationic antibiotics, including aminoglycosides. This study highlights the complexity of the regulatory network controlling resistance to cationic antibiotics and host peptides in P. aeruginosa, which has major relevance in the development and deployment of cationic antimicrobials.

scholarly journals Polymyxin B Resistance and Biofilm Formation in Vibrio cholerae Are Controlled by the Response Regulator CarR

2015 ◽  
Vol 83 (3) ◽  
pp. 1199-1209 ◽  
Author(s):  
Kivanc Bilecen ◽  
Jiunn C. N. Fong ◽  
Andrew Cheng ◽  
Christopher J. Jones ◽  
David Zamorano-Sánchez ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Biofilm Formation ◽  
Lipid A ◽  
Response Regulator ◽  
Regulatory Region ◽  
Regulatory System ◽  
Polymyxin B ◽  
Content Type ◽  
Two Component ◽  
Antimicrobial Peptide Resistance

Two-component systems play important roles in the physiology of many bacterial pathogens.Vibrio cholerae's CarRS two-component regulatory system negatively regulates expression ofvps(Vibriopolysaccharide) genes and biofilm formation. In this study, we report that CarR confers polymyxin B resistance by positively regulating expression of thealmEFGgenes, whose products are required for glycine and diglycine modification of lipid A. We determined that CarR directly binds to the regulatory region of thealmEFGoperon. Similarly to acarRmutant, strains lackingalmE,almF, andalmGexhibited enhanced polymyxin B sensitivity. We also observed that strains lackingalmEor thealmEFGoperon have enhanced biofilm formation. Our results reveal that CarR regulates biofilm formation and antimicrobial peptide resistance inV. cholerae.

scholarly journals Role of the LytSR Two-Component Regulatory System in Adaptation to Cationic Antimicrobial Peptides in Staphylococcus aureus

2013 ◽  
Vol 57 (8) ◽  
pp. 3875-3882 ◽  
Author(s):  
Soo-Jin Yang ◽  
Yan Q. Xiong ◽  
Michael R. Yeaman ◽  
Kenneth W. Bayles ◽  
Wessam Abdelhady ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Peptides ◽  
Regulatory System ◽  
Target Tissue ◽  
Adaptive Responses ◽  
Cationic Antimicrobial Peptide ◽  
Cationic Antimicrobial Peptides ◽  
Content Type ◽  
Response System ◽  
Two Component

ABSTRACTMany host defense cationic antimicrobial peptides (HDPs) perturb the staphylococcal cell membrane (CM) and alter transmembrane potential (ΔΨ) as key parts of their lethal mechanism. Thus, a sense-response system for detecting and mediating adaptive responses to such stresses could impact organism survival; theStaphylococcus aureusLytSR two-component regulatory system (TCRS) may serve as such a ΔΨ sensor. One well-known target of this system is thelrgABoperon, which, along with the relatedcidABCoperon, has been shown to be a regulator in the control of programmed cell death and lysis. We used an isogenic set ofS. aureusstrains: (i) UAMS-1, (ii) its isogenic ΔlytSand ΔlrgABmutants, and (iii) plasmid-complemented ΔlytSRand ΔlrgABmutants. The ΔlytSstrain displayed significantly increasedin vitrosusceptibilities to all HDPs tested (neutrophil-derived human neutrophil peptide 1 [hNP-1], platelet-derived thrombin-induced platelet microbicidal proteins [tPMPs], and the tPMP-mimetic peptide RP-1), as well as to calcium-daptomycin (DAP), a cationic antimicrobial peptide (CAP). In contrast, the ΔlrgABstrain exhibited no significant changes in susceptibilities to these cationic peptides, indicating that althoughlytSRpositively regulates transcription oflrgAB, increased HDP/CAP susceptibilities in the ΔlytSmutant werelrgABindependent. Further, parental UAMS-1 (but not the ΔlytSmutant) became more resistant to hNP-1 and DAP following pretreatment with carbonyl cyanidem-chlorophenylhydrazone (CCCP) (a CM-depolarizing agent). Of note,lytSR-dependent survival against CAP/HDP killing was not associated with changes in either surface positive charge, expression ofmprFanddlt, or CM fluidity. The ΔlytSstrain (but not the ΔlrgABmutant) displayed a significant reduction in target tissue survival in an endocarditis model during DAP treatment. Collectively, these results suggest that thelytSRTCRS plays an important role in adaptive responses ofS. aureusto CM-perturbing HDPs/CAPs, likely by functioning as a sense-response system for detecting subtle changes in ΔΨ.

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 NasT-Mediated Antitermination Plays an Essential Role in the Regulation of the Assimilatory Nitrate Reductase Operon in Azotobacter vinelandii

2012 ◽  
Vol 78 (18) ◽  
pp. 6558-6567 ◽  
Author(s):  
Baomin Wang ◽  
Leland S. Pierson ◽  
Christopher Rensing ◽  
Malkanthi K. Gunatilaka ◽  
Christina Kennedy
Keyword(s):  
Nitrogen Fixation ◽  
Rna Binding ◽  
Azotobacter Vinelandii ◽  
Regulatory System ◽  
Enteric Bacteria ◽  
Regulatory Function ◽  
Transcriptional Terminator ◽  
Content Type ◽  
Sequence Elements ◽  
Nitrate And Nitrite

ABSTRACTAzotobacter vinelandiiis a well-studied model system for nitrogen fixation in bacteria. Regulation of nitrogen fixation inA. vinelandiiis independent of NtrB/NtrC, a conserved nitrogen regulatory system in proteobacteria. Previous work showed that anntrCmutation inA. vinelandiiresulted in a loss of induction of assimilatory nitrate and nitrite reductases encoded by thenasABoperon. In addition to NtrC, several other proteins, including NasT, a protein containing a potential RNA-binding domain ANTAR (AmiR andNasRtranscriptionantiterminationregulators), have been implicated innasABregulation. In this work, we characterize the sequence upstream ofnasAand identify several DNA sequence elements, including two potential NtrC binding sites and a putative intrinsic transcriptional terminator upstream ofnasAthat are potentially involved innasABregulation. Our analyses confirm that thenasABpromoter,PnasA, is under NtrC control. However, unlike NtrC-regulated promoters in enteric bacteria,PnasAshows high activity in the presence of ammonium; in addition, thePnasAactivity is altered in thenifAgene mutation background. We discuss the implication of these results on NtrC-mediated regulation inA. vinelandii. Our study provides direct evidence that induction ofnasABis regulated by NasT-mediated antitermination, which occurs within the leader region of the operon. The results also support the hypothesis that NasT binds the promoter proximal hairpin ofnasABfor its regulatory function, which contributes to the understanding of the regulatory mechanism of ANTAR-containing antiterminators.

scholarly journals The BaeSR Two-Component Regulatory System Mediates Resistance to Condensed Tannins in Escherichia coli

2007 ◽  
Vol 74 (2) ◽  
pp. 535-539 ◽  
Author(s):  
Erwin G. Zoetendal ◽  
Alexandra H. Smith ◽  
Monica A. Sundset ◽  
Roderick I. Mackie
Keyword(s):  
Escherichia Coli ◽  
Cell Envelope ◽  
Expression Profiles ◽  
Stress Protein ◽  
Gene Expression Profiles ◽  
Regulatory System ◽  
Multidrug Transporter ◽  
Resistance Strategies ◽  
Envelope Stress ◽  
Two Component

ABSTRACT The gene expression profiles of Escherichia coli strains grown anaerobically with or without Acacia mearnsii (black wattle) extract were compared to identify tannin resistance strategies. The cell envelope stress protein gene spy and the multidrug transporter-encoding operon mdtABCD, both under the control of the BaeSR two-component regulatory system, were significantly up-regulated in the presence of tannins. BaeSR mutants were more tannin sensitive than their wild-type counterparts.

scholarly journals Interaction of the GraRS Two-Component System with the VraFG ABC Transporter To Support Vancomycin-Intermediate Resistance in Staphylococcus aureus

2007 ◽  
Vol 51 (8) ◽  
pp. 2679-2689 ◽  
Author(s):  
Michael Meehl ◽  
Silvia Herbert ◽  
Friedrich Götz ◽  
Ambrose Cheung
Keyword(s):  
Staphylococcus Aureus ◽  
Abc Transporter ◽  
Regulatory System ◽  
Polymyxin B ◽  
Current Treatment ◽  
Peptide Antibiotics ◽  
Genetic Changes ◽  
Resistance Phenotype ◽  
Two Component ◽  
Intermediate Resistance

ABSTRACTCurrent treatment for serious infections caused by methicillin-resistantStaphylococcus aureusrelies heavily upon the glycopeptide antibiotic vancomycin. Unfortunately, this practice has led to an intermediate resistance phenotype that is particularly difficult to treat in invasive staphylococcal diseases, such as septicemia and its metastatic complications, including endocarditis. Although the vancomycin-intermediate resistance phenotype has been linked to abnormal cell wall structures and autolytic rates, the corresponding genetic changes have not been fully elucidated. Previously, whole-genome array studies listed numerous genes that are overexpressed in vancomycin-intermediate sensitive strains, includinggraRS(SACOL0716 to -0717), encoding a two-component regulatory system (TCRS), as well as the adjacentvraFG(SACOL0718 to -0720), encoding an ATP-binding cassette (ABC) transporter; but the exact contribution of these genes to increased vancomycin resistance has not been defined. In this study, we showed that isogenic strains with mutations in genes encoding the GraRS TCRS and the VraFG ABC transporter are hypersensitive to vancomycin as well as polymyxin B. Moreover, GraRS regulates the expression of the adjacent VraFG pump, reminiscent of gram-positive bacteriocin-immunity regulons. Mutations ofgraRSandvraFGalso led to increased autolytic rates and a more negative net surface charge, which may explain, in part, to their increased sensitivity to cationic antimicrobial peptides. Taken together, these data reveal an important genetic mediator to the vancomycin-intermediateS. aureusphenotype and may hold clues to the selective pressures on staphylococci upon exposure to selective cationic peptide antibiotics used in clinical practice.

scholarly journals Characterization of the CpxRA Regulon in Haemophilus ducreyi

2010 ◽  
Vol 78 (11) ◽  
pp. 4779-4791 ◽  
Author(s):  
Maria Labandeira-Rey ◽  
Chad A. Brautigam ◽  
Eric J. Hansen
Keyword(s):  
Stress Response ◽  
Response Regulator ◽  
Cell Envelope ◽  
Bacterial Species ◽  
Regulatory System ◽  
Promoter Regions ◽  
Mobility Shift ◽  
Envelope Stress ◽  
Two Component ◽  
Genes Encoding

ABSTRACT The H aemophilus ducreyi 35000HP genome encodes a homolog of the CpxRA two-component cell envelope stress response system originally characterized in E scherichia coli. CpxR, the cytoplasmic response regulator, was shown previously to be involved in repression of the expression of the lspB-lspA2 operon (M. Labandeira-Rey, J. R. Mock, and E. J. Hansen, Infect. Immun. 77:3402-3411, 2009). In the present study, the H. ducreyi CpxR and CpxA proteins were shown to closely resemble those of other well-studied bacterial species. A cpxA deletion mutant and a CpxR-overexpressing strain were used to explore the extent of the CpxRA regulon. DNA microarray and real-time reverse transcriptase (RT) PCR analyses indicated several potential regulatory targets for the H. ducreyi CpxRA two-component regulatory system. Electrophoretic mobility shift assays (EMSAs) were used to prove that H. ducreyi CpxR interacted with the promoter regions of genes encoding both known and putative virulence factors of H. ducreyi, including the lspB-lspA2 operon, the flp operon, and dsrA. Interestingly, the use of EMSAs also indicated that H. ducreyi CpxR did not bind to the promoter regions of several genes predicted to encode factors involved in the cell envelope stress response. Taken together, these data suggest that the CpxRA system in H. ducreyi, in contrast to that in E. coli, may be involved primarily in controlling expression of genes not involved in the cell envelope stress response.

scholarly journals Identification and Genetic Characterization of PmrA-Regulated Genes and Genes Involved in Polymyxin B Resistance in Salmonella enterica Serovar Typhimurium

2002 ◽  
Vol 70 (12) ◽  
pp. 6770-6778 ◽  
Author(s):  
Rita Tamayo ◽  
Sara S. Ryan ◽  
Andrea J. McCoy ◽  
John S. Gunn
Keyword(s):  
Salmonella Enterica ◽  
Lipid A ◽  
Regulatory System ◽  
Enteric Bacteria ◽  
Polymyxin B ◽  
High Iron ◽  
Transposon Insertion ◽  
Mucosal Surfaces ◽  
Serovar Typhimurium

ABSTRACT Salmonella enterica serovar Typhimurium encounters antimicrobial peptides (AP) within the phagosomes of professional phagocytes and at intestinal mucosal surfaces. Salmonella serovar Typhimurium utilizes the two-component regulatory system PmrA-PmrB, which is activated in response to the environmental conditions encountered in vivo, to regulate resistance to several AP, including polymyxin B (PM). Random MudJ transposon mutagenesis was used to identify PmrA-PmrB-regulated genes, as well as genetic loci necessary for PM resistance. Three different phenotypic classes of genes were identified: those necessary for PM resistance and regulated by PmrA, those necessary for PM resistance and not regulated by PmrA, and PmrA-regulated genes not required for PM resistance. Loci identified as necessary for PM resistance showed between 6- and 192-fold increased sensitivities to PM, and transposon insertion sites include surA, tolB, and gnd. PmrA-regulated loci identified included dgoA and yibD and demonstrated 500- and 2,500-fold activation by PmrA, respectively. The role of the identified loci in aminoarabinose modification of lipid A was determined by paper chromatography. The gnd mutant demonstrated a loss of aminoarabinose from lipid A, which was suggested to be due to a polar effect on the downstream gene pmrE. The remaining PMs mutants (surA and tolB), as well as the two PmrA-regulated gene (yibD and dgoA) mutants, retained aminoarabinose on lipid A. yibD, dgoA, and gnd (likely affecting pmrE) played no role in PmrA-regulated resistance to high iron concentrations, while surA and tolB mutations grew poorly on high iron media. All PMs mutants identified in this study demonstrated a defect in virulence compared to wild-type Salmonella serovar Typhimurium when administered orally to mice, while the PmrA-regulated gene (yibD and dgoA) mutants showed normal virulence in mice. These data broaden our understanding of in vivo gene regulation, lipopolysaccharide modification, and mechanisms of resistance to AP in enteric bacteria.

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