scholarly journals The Escherichia coli CpxA-CpxR Envelope Stress Response System Regulates Expression of the Porins OmpF and OmpC

2005 ◽  
Vol 187 (16) ◽  
pp. 5723-5731 ◽  
Author(s):  
Eric Batchelor ◽  
Don Walthers ◽  
Linda J. Kenney ◽  
Mark Goulian
Keyword(s):  
Escherichia Coli ◽  
Stress Response ◽  
Response Regulator ◽  
Gene Encoding ◽  
Fluorescent Reporter ◽  
Response System ◽  
Dnase I Footprinting ◽  
Envelope Stress ◽  
Two Component ◽  
Stress Response System

ABSTRACT We performed transposon mutagenesis of a two-color fluorescent reporter strain to identify new regulators of the porin genes ompF and ompC in Escherichia coli. Screening of colonies by fluorescence microscopy revealed numerous mutants that exhibited interesting patterns of porin expression. One mutant harbored an insertion in the gene encoding the histidine kinase CpxA, the sensor for a two-component signaling system that responds to envelope stress. The cpxA mutant exhibited increased transcription of ompC and a very strong decrease in transcription of ompF under conditions in which acetyl phosphate levels were high. Subsequent genetic analysis revealed that this phenotype is dependent on phosphorylation of the response regulator CpxR and that activation of CpxA in wild-type cells results in similar regulation of porin expression. Using DNase I footprinting, we demonstrated that CpxR binds upstream of both the ompF and ompC promoters. It thus appears that two distinct two-component systems, CpxA-CpxR and EnvZ-OmpR, converge at the porin promoters. Within the context of envelope stress, outer membrane beta-barrel proteins have generally been associated with the sigma E pathway. However, at least for the classical porins OmpF and OmpC, our results show that the Cpx envelope stress response system plays a role in regulating their expression.

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 Activation of the Cpx-envelope stress response system promotes tolerance to antibacterials delivered by arginine-rich peptides and aminoglycosides in Escherichia coli

2020 ◽  
Author(s):  
Jakob Frimodt-Møller ◽  
Andreas Koulouktsis ◽  
Godefroid Charbon ◽  
Marit Otterlei ◽  
Peter E. Nielsen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Stress Response ◽  
Cell Penetrating Peptides ◽  
Resistant Bacteria ◽  
Antimicrobial Compounds ◽  
Inner Membrane ◽  
Response System ◽  
Envelope Stress ◽  
Cell Penetrating ◽  
Stress Response System

AbstractCell penetrating peptides (CPP) are increasingly used for cellular drug delivery in both pro- and eukaryotic cells, and oligoarginines have attracted special attention. However; their mechanism of action, particularly for prokaryotes is still unknown. Arginine-rich CPPs (R-CPP) efficiently delivers the antimicrobial peptide nucleic acid (PNA) into bacteria. Here, we show that resistance to an R-CPP PNA conjugate in Escherichia coli requires multiple genetic modifications and is specific to R-CPP and not to the PNA-part. An integral part of the resistance was the constitutively activated Cpx-envelope stress response system (cpx*), which decreased the cytoplasmic membrane potential and thereby indicates an indirectly energy dependent uptake mechanism. Interestingly, cpx* mutants also showed increased tolerance to aminoglycosides and R-CPP conjugated to a peptide targeting the DNA sliding clamp; i.e., similar uptake in E. coli for these antimicrobial compounds. We speculate that the cpx* phenotype could create an evolutionary opportunity to adapt and evolve in the presence of either compounds.Author summaryThe emergence of multidrug resistant bacteria is raising the need for new classes of antibiotics. Peptide nucleic acids (PNAs) may fill this requirement by their ability to block translation of essential mRNAs and hence inhibit growth. PNA needs conjugation to a delivery peptide (cell penetrating peptide; CPP) to enter the bacteria. Arginine-rich CPPs (CPPR) are receiving a lot of attention for use as delivery vessels. Here, we show, for the first time, CPPR-PNA resistance in Escherichia coli directed towards the delivery peptide. Consequently, resistance also applies to other antimicrobial compounds delivered by the same carrier. An integral part of CPPR resistance is due to a constitutive active Cpx-response system, which leads to a decreased electric potential (ΔΨ) across the inner membrane. The decreased ΔΨ is a result of down-regulation of two aerobic respiratory operons, namely NADH:ubiquinone oxidoreductase complex I and cytochrome bo3 ubiquinol oxidase. The decreased ΔΨ also led to increased tolerance to aminoglycosides. This shows that a (large) negative ΔΨ is important for providing sufficient free energy for membrane translocation of both CPPR and that the inner membrane is the main barrier for entry of both arginine-rich delivery peptides and aminoglycosides.

scholarly journals The Cpx Stress Response System Potentiates the Fitness and Virulence of Uropathogenic Escherichia coli

2013 ◽  
Vol 81 (5) ◽  
pp. 1450-1459 ◽  
Author(s):  
Irina Debnath ◽  
J. Paul Norton ◽  
Amelia E. Barber ◽  
Elizabeth M. Ott ◽  
Bijaya K. Dhakal ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Stress Response ◽  
Aminoglycoside Antibiotic ◽  
Deletion Mutants ◽  
Content Type ◽  
Response System ◽  
Stress Response System ◽  
Tract Infections ◽  
Auxiliary Factor

ABSTRACTStrains of uropathogenicEscherichia coli(UPEC) are the primary cause of urinary tract infections, representing one of the most widespread and successful groups of pathogens on the planet. To colonize and persist within the urinary tract, UPEC must be able to sense and respond appropriately to environmental stresses, many of which can compromise the bacterial envelope. The Cpx two-component envelope stress response system is comprised of the inner membrane histidine kinase CpxA, the cytosolic response regulator CpxR, and the periplasmic auxiliary factor CpxP. Here, by using deletion mutants along with mouse and zebrafish infection models, we show that the Cpx system is critical to the fitness and virulence of two reference UPEC strains, the cystitis isolate UTI89 and the urosepsis isolate CFT073. Specifically, deletion of thecpxRAoperon impaired the ability of UTI89 to colonize the murine bladder and greatly reduced the virulence of CFT073 during both systemic and localized infections within zebrafish embryos. These defects coincided with diminished host cell invasion by UTI89 and increased sensitivity of both strains to complement-mediated killing and the aminoglycoside antibiotic amikacin. Results obtained with thecpxPdeletion mutants were more complicated, indicating variable strain-dependent and niche-specific requirements for this well-conserved auxiliary factor.

scholarly journals Phage-shock-protein (Psp) Envelope Stress Response: Evolutionary History & Discovery of Novel Players

2020 ◽  
Author(s):  
Janani Ravi ◽  
Vivek Anantharaman ◽  
Samuel Zorn Chen ◽  
Pratik Datta ◽  
L Aravind ◽  
...  
Keyword(s):  
Stress Response ◽  
Web Application ◽  
Cell Envelope ◽  
Contextual Information ◽  
Specific Cell ◽  
Bacterial Phyla ◽  
Response System ◽  
Envelope Stress ◽  
Stress Response System ◽  
Conserved Gene

AbstractThe phage shock protein (Psp) stress-response system protects bacteria from envelope stress and stabilizes the cell membrane. Recent work from our group suggests that the psp systems have evolved independently in distinct Gram-positive and Gram-negative bacterial clades to effect similar stress response functions. Despite the prevalence of the key effector, PspA, and the functional Psp system, the various genomic contexts of Psp proteins, as well as their evolution across the kingdoms of life, have not yet been characterized. We have developed a computational pipeline for comparative genomics and protein sequence-structure-function analyses to identify sequence homologs, phyletic patterns, domain architectures, gene neighborhoods, and evolution of the candidates across the tree of life. This integrative pipeline enabled us to make several new discoveries, including the truly universal nature of PspA and the ancestry of the PspA/Snf7 dating all the way back to the Last Universal Common Ancestor. Using contextual information from conserved gene neighborhoods and their domain architectures, we delineated the phyletic patterns of all the Psp members. Next, we systematically identified all possible ‘flavors’ and genomic neighborhoods of the Psp systems. Finally, we traced their evolution, leading us to several interesting findings of their occurrence and co-migration that together point to the functions and roles of Psp in stress-response systems that are often lineage-specific. Conservation of the Psp systems across bacterial phyla emphasizes the established importance of this stress response system in prokaryotes, while the modularity in various lineages is indicative of adaptation to bacteria-specific cell-envelope structures, lifestyles, and adaptation strategies. We also developed an interactive web application that hosts all the data and results in this study that researchers can explore (https://jravilab.shinyapps.io/psp-evolution).

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 Induction Kinetics of a Conditional pH Stress Response System in Escherichia coli

2009 ◽  
Vol 393 (2) ◽  
pp. 272-286 ◽  
Author(s):  
Georg Fritz ◽  
Christiane Koller ◽  
Korinna Burdack ◽  
Larissa Tetsch ◽  
Ina Haneburger ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Stress Response ◽  
Response System ◽  
Induction Kinetics ◽  
Ph Stress ◽  
Stress Response System ◽  
Kinetics Of

scholarly journals The Positive Regulator, TraJ, of the Escherichia coli F Plasmid Is Unstable in a cpxA* Background

2002 ◽  
Vol 184 (20) ◽  
pp. 5781-5788 ◽  
Author(s):  
Michael J. Gubbins ◽  
Isabella Lau ◽  
William R. Will ◽  
Janet M. Manchak ◽  
Tracy L. Raivio ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Stress Response ◽  
Response Regulator ◽  
Cell Envelope ◽  
Conjugative Plasmid ◽  
F Plasmid ◽  
Gain Of Function ◽  
Positive Regulator ◽  
Envelope Stress ◽  
Detection Of Stress

ABSTRACT The Cpx (conjugative plasmid expression) stress response of Escherichia coli is induced in response to extracytoplasmic signals generated in the cell envelope, such as misfolded proteins in the periplasm. Detection of stress is mediated by the membrane-bound histidine kinase, CpxA. Signaling of the response regulator CpxR by activated CpxA results in the expression of several factors required for responding to cell envelope stress. CpxA was originally thought to be required for the expression of the positive regulator of the F plasmid transfer (tra) operon, TraJ. It was later determined that constitutive gain-of-function mutations in cpxA led to activation of the Cpx envelope stress response and decreased TraJ expression. In order to determine the nature of the downregulation of TraJ, the level of expression of TraJ, TraM, and TraY, the F-encoded regulatory proteins of the F tra region, was determined both in a cpxA* background and in a wild-type background in which the Cpx stress response was induced by overexpression of the outer membrane lipoprotein, NlpE. Our results suggest that TraJ downregulation is controlled by a posttranscriptional mechanism that operates in the cytoplasm in response to upregulation of the Cpx stress response by both the cpxA* gain-of-function mutation and the overexpression of NlpE.

scholarly journals Toward a Semisynthetic Stress Response System To Engineer Microbial Solvent Tolerance

mBio ◽  
2012 ◽  
Vol 3 (5) ◽  
Author(s):  
Kyle A. Zingaro ◽  
Eleftherios Terry Papoutsakis
Keyword(s):  
Escherichia Coli ◽  
Stress Response ◽  
Heat Shock ◽  
Heat Shock Proteins ◽  
Solvent Tolerance ◽  
Content Type ◽  
Response System ◽  
Wide Range ◽  
Stress Response System ◽  
Shock Proteins

ABSTRACT Strain tolerance to toxic metabolites is an important trait for many biotechnological applications, such as the production of solvents as biofuels or commodity chemicals. Engineering a complex cellular phenotype, such as solvent tolerance, requires the coordinated and tuned expression of several genes. Using combinations of heat shock proteins (HSPs), we engineered a semisynthetic stress response system in Escherichia coli capable of tolerating high levels of toxic solvents. Simultaneous overexpression of the HSPs GrpE and GroESL resulted in a 2-fold increase in viable cells (CFU) after exposure to 5% (vol/vol) ethanol for 24 h. Co-overexpression of GroESL and ClpB on coexisting plasmids resulted in 1,130%, 78%, and 25% increases in CFU after 24 h in 5% ethanol, 1% n-butanol, and 1% i-butanol, respectively. Co-overexpression of GrpE, GroESL, and ClpB on a single plasmid produced 200%, 390%, and 78% increases in CFU after 24 h in 7% ethanol, 1% n-butanol, or 25% 1,2,4-butanetriol, respectively. Overexpression of other autologous HSPs (DnaK, DnaJ, IbpA, and IbpB) alone or in combinations failed to improve tolerance. Expression levels of HSP genes, tuned through inducible promoters and the plasmid copy number, affected the effectiveness of the engineered stress response system. Taken together, these data demonstrate that tuned co-overexpression of GroES, GroEL, ClpB, and GrpE can be engaged to engineer a semisynthetic stress response system capable of greatly increasing the tolerance of E. coli to solvents and provides a starting platform for engineering customized tolerance to a wide variety of toxic chemicals. IMPORTANCE Microbial production of useful chemicals is often limited by the toxicity of desired products, feedstock impurities, and undesired side products. Improving tolerance is an essential step in the development of practical platform organisms for production of a wide range of chemicals. By overexpressing autologous heat shock proteins in Escherichia coli, we have developed a modular semisynthetic stress response system capable of improving tolerance to ethanol, n-butanol, and potentially other toxic solvents. Using this system, we demonstrate that a practical stress response system requires both tuning of individual gene components and a reliable framework for gene expression. This system can be used to seek out new interacting partners to improve the tolerance phenotype and can be used in the development of more robust solvent production strains.

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