The two-component response regulator PprB modulates quorum-sensing signal production and global gene expression in Pseudomonas aeruginosa

The bacterial phytochrome of Pseudomonas aeruginosa (PaBphP) is an in vitro-active red/far-red light sensor histidine kinase of a two-component regulatory system. Despite solid biochemical data, its function in this heterotrophic, opportunistic pathogen is still unknown. Previous studies established that the genes encoding the two necessary phytochrome components BphO, a chromophore-producing haem oxygenase, and BphP, the apo-phytochrome, are co-transcribed in a bicistronic operon. Transcription has been shown to be induced in the stationary phase and to be dependent on the alternative sigma factor RpoS. Here we show an additional regulation of bphP expression through the quorum-sensing (QS) regulator LasR. This regulation is also reflected in a combination of expression profile experiments and proteome analyses of wild-type and phytochrome-deficient strains. While PaBphP has a pleiotropic effect on global gene expression, 66 % of the downregulated genes in the phytochrome mutant display a link to the Las QS system. Most of these genes seem to be indirectly regulated by LasR through BphP and the unknown response regulator BphR. A model of phytochrome function within the Las QS network is presented.

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Molecular Mechanisms of Phosphate Stress Activation of Pseudomonas aeruginosa Quorum Sensing Systems

mSphere ◽

10.1128/msphere.00119-20 ◽

2020 ◽

Vol 5 (2) ◽

Cited By ~ 6

Author(s):

Xianfa Meng ◽

Stephen Dela Ahator ◽

Lian-Hui Zhang

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Response Regulator ◽

Regulatory System ◽

Regulatory Genes ◽

Phosphate Deficiency ◽

Content Type ◽

Sensing Systems ◽

Two Component ◽

Phosphate Depletion

ABSTRACT The hierarchical quorum sensing (QS) systems of Pseudomonas aeruginosa, consisting of las, pqs, and rhl, coordinate the expression of bacterial virulence genes. Previous studies showed that under phosphate deficiency conditions, two-component regulatory system PhoRB could activate various genes involved in cytotoxicity through modulation of QS systems, but the mechanism by which PhoR/PhoB influences QS remains largely unknown. Here, we provide evidence that among the key QS regulatory genes in P. aeruginosa, rhlR, pqsA, mvfR, and lasI were activated by the response regulator PhoB under phosphate-depleted conditions. We show that PhoB is a strong competitor against LasR and RsaL for binding to the promoter of lasI and induces significant expression of lasI, rhlR, and mvfR. However, expression of lasI, encoding the signal 3-oxo-C12-HSL, was increased only marginally under the same phosphate-depleted conditions. This seeming inconsistency was attributed to the induction of pvdQ, which encodes an enzyme for degradation of 3-oxo-C12-HSL signal molecules. Taken together, the results from this study demonstrate that through the two-component regulatory system PhoR/PhoB, phosphate depletion stress could influence the QS network by modulating several key regulators, including lasI, rhlR, mvfR, and pvdQ. The findings highlight not only the potency of the PhoR/PhoB-mediated bacterial stress response mechanism but also the plasticity of the P. aeruginosa QS systems in coping with the changed environmental conditions. IMPORTANCE It is not fully understood how phosphate deficiency could influence the virulence of Pseudomonas aeruginosa through modulation of the bacterial QS systems. This report presents a systemic investigation on the impact of phosphate depletion on the hierarchy of quorum sensing systems of P. aeruginosa. The results showed that phosphate stress could have an extensive impact on the QS networks of this bacterial pathogen. Among the 7 QS regulatory genes representing the 3 sets of QS systems tested, 4 were significantly upregulated by phosphate depletion stress through the PhoR/PhoB two-component regulatory system, especially the upstream QS regulatory gene lasI. We also present evidence that the response regulator PhoB was a strong competitor against the las regulators LasR and RsaL for the lasI promoter, unveiling the mechanistic basis of the process by which phosphate stress could modulate the bacterial QS systems.

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

Microbiology ◽

10.1099/mic.0.26882-0 ◽

2004 ◽

Vol 150 (6) ◽

pp. 1851-1857 ◽

Cited By ~ 21

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.

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The YebC Family Protein PA0964 Negatively Regulates the Pseudomonas aeruginosa Quinolone Signal System and Pyocyanin Production

Journal of Bacteriology ◽

10.1128/jb.00428-08 ◽

2008 ◽

Vol 190 (18) ◽

pp. 6217-6227 ◽

Cited By ~ 72

Author(s):

Haihua Liang ◽

Lingling Li ◽

Zhaolin Dong ◽

Michael G. Surette ◽

Kangmin Duan

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Virulence Factors ◽

Response Regulator ◽

Initial Study ◽

Pfam Family ◽

Swarming Motility ◽

Sensing Systems ◽

Family Protein ◽

Pyocyanin Production

ABSTRACT Bacterial pathogenicity is often manifested by the expression of various cell-associated and secreted virulence factors, such as exoenzymes, protease, and toxins. In Pseudomonas aeruginosa, the expression of virulence genes is coordinately controlled by the global regulatory quorum-sensing systems, which includes the las and rhl systems as well as the Pseudomonas quinolone signal (PQS) system. Phenazine compounds are among the virulence factors under the control of both the rhl and PQS systems. In this study, regulation of the phzA1B1C1D1E1 (phzA1) operon, which is involved in phenazine synthesis, was investigated. In an initial study of inducing conditions, we observed that phzA1 was induced by subinhibitory concentrations of tetracycline. Screening of 13,000 mutants revealed 32 genes that altered phzA1 expression in the presence of subinhibitory tetracycline concentrations. Among them, the gene PA0964, designated pmpR ( p qsR-mediated P QS r egulator), has been identified as a novel regulator of the PQS system. It belongs to a large group of widespread conserved hypothetical proteins with unknown function, the YebC protein family (Pfam family DUF28). It negatively regulates the quorum-sensing response regulator pqsR of the PQS system by binding at its promoter region. Alongside phzA1 expression and phenazine and pyocyanin production, a set of virulence factors genes controlled by both rhl and the PQS were shown to be modulated by PmpR. Swarming motility and biofilm formation were also significantly affected. The results added another layer of regulation in the rather complex quorum-sensing systems in P. aeruginosa and demonstrated a clear functional clue for the YebC family proteins.

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Individual Matrix Metalloproteinases Control Distinct Transcriptional Responses in Airway Epithelial Cells Infected with Pseudomonas aeruginosa

Infection and Immunity ◽

10.1128/iai.00799-07 ◽

2007 ◽

Vol 75 (12) ◽

pp. 5640-5650 ◽

Cited By ~ 48

Author(s):

Sean Y. Kassim ◽

Sina A. Gharib ◽

Brigham H. Mecham ◽

Timothy P. Birkland ◽

William C. Parks ◽

...

Keyword(s):

Gene Expression ◽

Pseudomonas Aeruginosa ◽

Initial Point ◽

Global Gene Expression ◽

Airway Epithelial Cells ◽

Airway Epithelial ◽

Transcriptional Responses ◽

Matrix Metalloproteinase 7 ◽

Node Network ◽

Global Gene Expression Analysis

ABSTRACT Airway epithelium is the initial point of host-pathogen interaction in Pseudomonas aeruginosa infection, an important pathogen in cystic fibrosis and nosocomial pneumonia. We used global gene expression analysis to determine airway epithelial transcriptional responses dependent on matrilysin (matrix metalloproteinase 7 [MMP-7]) and stromelysin-2 (MMP-10), two MMPs induced by acute P. aeruginosa pulmonary infection. Extraction of differential gene expression (EDGE) analysis of gene expression changes in P. aeruginosa-infected organotypic tracheal epithelial cell cultures from wild-type, Mmp7 −/−, and Mmp10 −/− mice identified 2,091 matrilysin-dependent and 1,628 stromelysin-2-dependent genes that were differentially expressed. Key node network analysis showed that these MMPs controlled distinct gene expression programs involved in proliferation, cell death, immune responses, and signal transduction, among other host defense processes. Our results demonstrate discrete roles for these MMPs in regulating epithelial responses to Pseudomonas infection and show that a global genomics strategy can be used to assess MMP function.

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The two-component system CopRS maintains femtomolar levels of free copper in the periplasm of Pseudomonas aeruginosa using a phosphatase-based mechanism

10.1101/2020.05.13.092544 ◽

2020 ◽

Author(s):

Lorena Novoa-Aponte ◽

Fernando C. Soncini ◽

José M. Argüello

Keyword(s):

Pseudomonas Aeruginosa ◽

Phosphatase Activity ◽

Response Regulator ◽

Redox Enzymes ◽

Two Component System ◽

Component System ◽

Component Systems ◽

Two Component ◽

Two Component Systems ◽

Systems Control

ABSTRACTTwo component systems control periplasmic Cu+ homeostasis in Gram-negative bacteria. In characterized systems such as Escherichia coli CusRS, upon Cu+ binding to the periplasmic sensing domain of CusS, a cytoplasmic phosphotransfer domain phosphorylates the response regulator CusR. This drives the expression of efflux transporters, chaperones, and redox enzymes to ameliorate metal toxic effects. Here, we show that the Pseudomonas aeruginosa two component sensor histidine kinase CopS exhibits a Cu-dependent phosphatase activity that maintains a non-phosphorylated CopR when the periplasmic Cu levels are below its activation threshold. Upon Cu+ binding to the sensor, the phosphatase activity is blocked and the phosphorylated CopR activates transcription of the CopRS regulon. Supporting the model, mutagenesis experiments revealed that the ΔcopS strain showed constitutive high expression of the CopRS regulon, lower intracellular Cu+ levels, and larger Cu tolerance when compared to wild type cells. The invariant phospho-acceptor residue His235 of CopS was not required for the phosphatase activity itself, but necessary for its Cu-dependency. To sense the metal, the periplasmic domain of CopS binds two Cu+ ions at its dimeric interface. Homology modeling of CopS based on CusS structure (four Ag+ binding sites) clearly explains the different binding stoichiometries in both systems. Interestingly, CopS binds Cu+/2+ with 30 × 10−15 M affinities, pointing to the absence of free (hydrated) Cu+/2+ in the periplasm.IMPORTANCECopper is a micronutrient required as cofactor in redox enzymes. When free, copper is toxic, mismetallating proteins, and generating damaging free radicals. Consequently, copper overload is a strategy that eukaryotic cells use to combat pathogens. Bacteria have developed copper sensing transcription factors to control copper homeostasis. The cell envelope is the first compartment that has to cope with copper stress. Dedicated two component systems control the periplasmic response to metal overload. This manuscript shows that the copper sensing two component system present in Pseudomonadales exhibits a signal-dependent phosphatase activity controlling the activation of the response regulator, distinct from previously described periplasmic Cu sensors. Importantly, the data show that the sensor is activated by copper levels compatible with the absence of free copper in the cell periplasm. This emphasizes the diversity of molecular mechanisms that have evolved in various bacteria to manage the copper cellular distribution.

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Pseudomonas aeruginosa Biofilms Exposed to Imipenem Exhibit Changes in Global Gene Expression and β-Lactamase and Alginate Production

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.48.4.1175-1187.2004 ◽

2004 ◽

Vol 48 (4) ◽

pp. 1175-1187 ◽

Cited By ~ 202

Author(s):

Niels Bagge ◽

Martin Schuster ◽

Morten Hentzer ◽

Oana Ciofu ◽

Michael Givskov ◽

...

Keyword(s):

Gene Expression ◽

Pseudomonas Aeruginosa ◽

Lung Function ◽

Structural Changes ◽

Global Gene Expression ◽

Significant Differential Expression ◽

Alginate Production ◽

Impaired Lung Function ◽

Subinhibitory Concentrations ◽

Suppressive Antibiotic Therapy

ABSTRACT The lungs of cystic fibrosis (CF) patients are commonly colonized with Pseudomonas aeruginosa biofilms. Chronic endobronchial P. aeruginosa infections are impossible to eradicate with antibiotics, but intensive suppressive antibiotic therapy is essential to maintain the lung function of CF patients. The treatment often includes β-lactam antibiotics. How these antibiotics influence gene expression in the surviving biofilm population of P. aeruginosa is not clear. Thus, we used the microarray technology to study the effects of subinhibitory concentrations of a β-lactam antibiotic, imipenem, on gene expression in biofilm populations. Many genes showed small but statistically significant differential expression in response to imipenem. We identified 34 genes that were induced or repressed in biofilms exposed to imipenem more than fivefold compared to the levels of induction or repression for the controls. As expected, the most strongly induced gene was ampC, which codes for chromosomal β-lactamase. We also found that genes coding for alginate biosynthesis were induced by exposure to imipenem. Alginate production is correlated to the development of impaired lung function, and P. aeruginosa strains isolated from chronically colonized lungs of CF patients are nearly always mucoid due to the overproduction of alginate. Exposure to subinhibitory concentrations of imipenem caused structural changes in the biofilm, e.g., an increased biofilm volume. Increased levels of alginate production may be an unintended adverse consequence of imipenem treatment in CF patients.

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Global Gene Expression Profiles Suggest an Important Role for Nutrient Acquisition in Early Pathogenesis in a Plant Model of Pseudomonas aeruginosa Infection

Applied and Environmental Microbiology ◽

10.1128/aem.00860-08 ◽

2008 ◽

Vol 74 (18) ◽

pp. 5784-5791 ◽

Cited By ~ 18

Author(s):

Tiffany L. Weir ◽

Valerie J. Stull ◽

Dayakar Badri ◽

Lily A. Trunck ◽

Herbert P. Schweizer ◽

...

Keyword(s):

Gene Expression ◽

Pseudomonas Aeruginosa ◽

Salicylic Acid ◽

Expression Profiles ◽

Gene Expression Profiles ◽

Global Gene Expression ◽

Defense Responses ◽

N Gene ◽

Virulence Determinants ◽

In Planta

ABSTRACT Although Pseudomonas aeruginosa is an opportunistic pathogen that does not often naturally infect alternate hosts, such as plants, the plant-P. aeruginosa model has become a widely recognized system for identifying new virulence determinants and studying the pathogenesis of the organism. Here, we examine how both host factors and P. aeruginosa PAO1 gene expression are affected in planta after infiltration into incompatible and compatible cultivars of tobacco (Nicotiana tabacum L.). N. tabacum has a resistance gene (N) against tobacco mosaic virus, and although resistance to PAO1 infection is correlated with the presence of a dominant N gene, our data suggest that it is not a factor in resistance against PAO1. We did observe that the resistant tobacco cultivar had higher basal levels of salicylic acid and a stronger salicylic acid response upon infiltration of PAO1. Salicylic acid acts as a signal to activate defense responses in plants, limiting the spread of the pathogen and preventing access to nutrients. It has also been shown to have direct virulence-modulating effects on P. aeruginosa. We also examined host effects on the pathogen by analyzing global gene expression profiles of bacteria removed from the intracellular fluid of the two plant hosts. We discovered that the availability of micronutrients, particularly sulfate and phosphates, is important for in planta pathogenesis and that the amounts of these nutrients made available to the bacteria may in turn have an effect on virulence gene expression. Indeed, there are several reports suggesting that P. aeruginosa virulence is influenced in mammalian hosts by the availability of micronutrients, such as iron and nitrogen, and by levels of O2.

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Regulation of Quorum Sensing by RpoS inPseudomonas aeruginosa

Journal of Bacteriology ◽

10.1128/jb.182.15.4356-4360.2000 ◽

2000 ◽

Vol 182 (15) ◽

pp. 4356-4360 ◽

Cited By ~ 179

Author(s):

Marvin Whiteley ◽

Matthew R. Parsek ◽

E. P. Greenberg

Keyword(s):

Gene Expression ◽

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Gene Transcription ◽

Opportunistic Pathogen ◽

Null Mutant ◽

Global Regulators ◽

Acylhomoserine Lactone ◽

Sensing Systems

ABSTRACT The LasR-LasI and RhlR-RhlI quorum-sensing systems are global regulators of gene expression in the opportunistic pathogenPseudomonas aeruginosa. Previous studies suggest that the RhlR-RhlI system activates expression of rpoS. We constructed merodiploid strains of P. aeruginosa containing the native rpoS gene and an rpoS-lacZ fusion. Studies of lacZ transcription in these strains indicated that rpoS was not regulated by RhlR-RhlI. We also generated an rpoS null mutant. This rpoS mutant showed elevated levels of rhlI (but not rhlR) transcription, elevated levels of the RhlI-generated acylhomoserine lactone quorum-sensing signal, and elevated levels of RhlR-RhlI-regulated gene transcription. These findings indicate that there is a relationship between RpoS and quorum sensing, but rather than the RhlR-RhlI system influencing the expression ofrpoS, it appears that RpoS regulates rhlI.

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