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Constantino-Teles P, Jouault A, Touqui L, Saliba AM. Role of Host and Bacterial Lipids in Pseudomonas aeruginosa Respiratory Infections. Front Immunol 2022; 13:931027. [PMID: 35860265 PMCID: PMC9289105 DOI: 10.3389/fimmu.2022.931027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 06/07/2022] [Indexed: 11/13/2022] Open
Abstract
The opportunistic pathogen Pseudomonas aeruginosa is one of the most common agents of respiratory infections and has been associated with high morbidity and mortality rates. The ability of P. aeruginosa to cause severe respiratory infections results from the coordinated action of a variety of virulence factors that promote bacterial persistence in the lungs. Several of these P. aeruginosa virulence mechanisms are mediated by bacterial lipids, mainly lipopolysaccharide, rhamnolipid, and outer membrane vesicles. Other mechanisms arise from the activity of P. aeruginosa enzymes, particularly ExoU, phospholipase C, and lipoxygenase A, which modulate host lipid signaling pathways. Moreover, host phospholipases, such as cPLA2α and sPLA2, are also activated during the infectious process and play important roles in P. aeruginosa pathogenesis. These mechanisms affect key points of the P. aeruginosa-host interaction, such as: i) biofilm formation that contributes to bacterial colonization and survival, ii) invasion of tissue barriers that allows bacterial dissemination, iii) modulation of inflammatory responses, and iv) escape from host defenses. In this mini-review, we present the lipid-based mechanism that interferes with the establishment of P. aeruginosa in the lungs and discuss how bacterial and host lipids can impact the outcome of P. aeruginosa respiratory infections.
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Affiliation(s)
- Pamella Constantino-Teles
- Department of Microbiology, Immunology and Parasitology, Faculty of Medical Sciences, Rio de Janeiro State University, Rio de Janeiro, Brazil
| | - Albane Jouault
- Sorbonne Université, Centre de Recherche Saint-Antoine, Inserm, Institut Pasteur, Mucoviscidose et Bronchopathies Chroniques, Département Santé Globale, Paris, France
| | - Lhousseine Touqui
- Sorbonne Université, Centre de Recherche Saint-Antoine, Inserm, Institut Pasteur, Mucoviscidose et Bronchopathies Chroniques, Département Santé Globale, Paris, France
| | - Alessandra Mattos Saliba
- Department of Microbiology, Immunology and Parasitology, Faculty of Medical Sciences, Rio de Janeiro State University, Rio de Janeiro, Brazil
- *Correspondence: Alessandra Mattos Saliba,
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Hardy KS, Tessmer MH, Frank DW, Audia JP. Perspectives on the Pseudomonas aeruginosa Type III Secretion System Effector ExoU and Its Subversion of the Host Innate Immune Response to Infection. Toxins (Basel) 2021; 13:880. [PMID: 34941717 PMCID: PMC8708460 DOI: 10.3390/toxins13120880] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 11/19/2021] [Accepted: 12/04/2021] [Indexed: 12/02/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic, Gram-negative pathogen and an important cause of hospital acquired infections, especially in immunocompromised patients. Highly virulent P. aeruginosa strains use a type III secretion system (T3SS) to inject exoenzyme effectors directly into the cytoplasm of a target host cell. P. aeruginosa strains that express the T3SS effector, ExoU, associate with adverse outcomes in critically ill patients with pneumonia, owing to the ability of ExoU to rapidly damage host cell membranes and subvert the innate immune response to infection. Herein, we review the structure, function, regulation, and virulence characteristics of the T3SS effector ExoU, a highly cytotoxic phospholipase A2 enzyme.
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Affiliation(s)
- Kierra S. Hardy
- Department of Microbiology and Immunology, University of South Alabama College of Medicine, Mobile, AL 36608, USA;
- Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL 36608, USA
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Maxx H. Tessmer
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA;
| | - Dara W. Frank
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Jonathon P. Audia
- Department of Microbiology and Immunology, University of South Alabama College of Medicine, Mobile, AL 36608, USA;
- Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL 36608, USA
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3
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Wagener BM, Hu R, Wu S, Pittet JF, Ding Q, Che P. The Role of Pseudomonas aeruginosa Virulence Factors in Cytoskeletal Dysregulation and Lung Barrier Dysfunction. Toxins (Basel) 2021; 13:776. [PMID: 34822560 PMCID: PMC8625199 DOI: 10.3390/toxins13110776] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 10/24/2021] [Accepted: 10/28/2021] [Indexed: 12/19/2022] Open
Abstract
Pseudomonas (P.) aeruginosa is an opportunistic pathogen that causes serious infections and hospital-acquired pneumonia in immunocompromised patients. P. aeruginosa accounts for up to 20% of all cases of hospital-acquired pneumonia, with an attributable mortality rate of ~30-40%. The poor clinical outcome of P. aeruginosa-induced pneumonia is ascribed to its ability to disrupt lung barrier integrity, leading to the development of lung edema and bacteremia. Airway epithelial and endothelial cells are important architecture blocks that protect the lung from invading pathogens. P. aeruginosa produces a number of virulence factors that can modulate barrier function, directly or indirectly, through exploiting cytoskeleton networks and intercellular junctional complexes in eukaryotic cells. This review summarizes the current knowledge on P. aeruginosa virulence factors, their effects on the regulation of the cytoskeletal network and associated components, and molecular mechanisms regulating barrier function in airway epithelial and endothelial cells. A better understanding of these processes will help to lay the foundation for new therapeutic approaches against P. aeruginosa-induced pneumonia.
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Affiliation(s)
- Brant M. Wagener
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (B.M.W.); (R.H.); (S.W.); (J.-F.P.); (Q.D.)
- Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Division of Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Ruihan Hu
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (B.M.W.); (R.H.); (S.W.); (J.-F.P.); (Q.D.)
- Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Department of Internal Medicine, Guiqian International General Hospital, Guiyang 550024, China
| | - Songwei Wu
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (B.M.W.); (R.H.); (S.W.); (J.-F.P.); (Q.D.)
- Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jean-Francois Pittet
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (B.M.W.); (R.H.); (S.W.); (J.-F.P.); (Q.D.)
- Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Division of Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Qiang Ding
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (B.M.W.); (R.H.); (S.W.); (J.-F.P.); (Q.D.)
- Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Pulin Che
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (B.M.W.); (R.H.); (S.W.); (J.-F.P.); (Q.D.)
- Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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4
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A pipeline to evaluate inhibitors of the Pseudomonas aeruginosa exotoxin U. Biochem J 2021; 478:647-668. [PMID: 33459338 PMCID: PMC7886320 DOI: 10.1042/bcj20200780] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 01/15/2021] [Accepted: 01/18/2021] [Indexed: 01/07/2023]
Abstract
Pseudomonas aeruginosa has recently been highlighted by the World Health Organisation (WHO) as a major threat with high priority for the development of new therapies. In severe P. aeruginosa infections, the phospholipase activity of the type 3 secretion system toxin, ExoU, induces lysis of target host cells and results in the poorest clinical outcomes. We have developed an integrated pipeline to evaluate small molecule inhibitors of ExoU in vitro and in cultured cell models, including a disease-relevant corneal epithelial (HCE-T) scratch and infection model using florescence microscopy and cell viability assays. Compounds Pseudolipasin A, compound A and compound B were effective in vitro inhibitors of ExoU and mitigated P. aeruginosa ExoU-dependent cytotoxicity after infection of HCE-T cells at concentrations as low as 0.5 µM. Addition of the antimicrobial moxifloxacin controlled bacterial load, allowing these assays to be extended from 6 h to 24 h. P. aeruginosa remained cytotoxic to HCE-T cells with moxifloxacin, present at the minimal inhibitory concentration for 24 h, but, when used in combination with either Pseudolipasin A, compound A or compound B, a greater amount of viable cells and scratch healing were observed. Thus, our pipeline provides evidence that ExoU inhibitors could be used in combination with certain antimicrobials as a novel means to treat infections due to ExoU producing P. aeruginosa, as well as the means to identify more potent ExoU inhibitors for future therapeutics.
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5
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Armentrout EI, Kundracik EC, Rietsch A. Cell-type-specific hypertranslocation of effectors by the Pseudomonas aeruginosa type III secretion system. Mol Microbiol 2020; 115:305-319. [PMID: 33012037 DOI: 10.1111/mmi.14617] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 09/22/2020] [Indexed: 12/23/2022]
Abstract
Many Gram-negative pathogens use a type III secretion system (T3SS) to promote disease by injecting effector proteins into host cells. Common to many T3SSs is that injection of effector proteins is feedback inhibited. The mechanism of feedback inhibition and its role in pathogenesis are unclear. In the case of P. aeruginosa, the effector protein ExoS is central to limiting effector injection. ExoS is bifunctional, with an amino-terminal RhoGAP and a carboxy-terminal ADP-ribosyltransferase domain. We demonstrate that both domains are required to fully feedback inhibit effector injection. The RhoGAP-, but not the ADP-ribosyltransferase domain of the related effector protein ExoT also participates. Feedback inhibition does not involve translocator insertion nor pore-formation. Instead, feedback inhibition is due, in part, to a loss of the activating trigger for effector injection, and likely also decreased translocon stability. Surprisingly, feedback inhibition is abrogated in phagocytic cells. The lack of feedback inhibition in these cells requires phagocytic uptake of the bacteria, but cannot be explained through acidification of the phagosome or calcium limitation. Given that phagocytes are crucial for controlling P. aeruginosa infections, our data suggest that feedback inhibition allows P. aeruginosa to direct its effector arsenal against the cell types most damaging to its survival.
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Affiliation(s)
- Erin I Armentrout
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH, USA
| | - Emma C Kundracik
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH, USA
| | - Arne Rietsch
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH, USA
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Balczon R, Morrow KA, Leavesley S, Francis CM, Stevens TC, Agwaramgbo E, Williams C, Stevens RP, Langham G, Voth S, Cioffi EA, Weintraub SE, Stevens T. Cystatin C regulates the cytotoxicity of infection-induced endothelial-derived β-amyloid. FEBS Open Bio 2020; 10:2464-2477. [PMID: 33030263 PMCID: PMC7609779 DOI: 10.1002/2211-5463.12997] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 08/25/2020] [Accepted: 10/05/2020] [Indexed: 02/06/2023] Open
Abstract
Infection of rat pulmonary microvascular endothelial cells with the bacterium Pseudomonas aeruginosa induces the production and release of cytotoxic oligomeric tau and beta amyloid (Aβ). Here, we characterized these cytotoxic amyloids. Cytotoxic behavior and oligomeric tau were partially resistant to digestion with proteinase K, but cytotoxicity was abolished by various denaturants including phenol, diethylpyrocarbonate (DEPC), and 1,1,1,3,3,3-hexafluoro-2-isopropanol (HFIP). Ultracentrifugation for 8 h at 150 000 g was required to remove cytotoxic activity from the supernatant. Ultracentrifugation, DEPC treatment, and immunodepletion using antibodies against Aβ also demonstrated that cytoprotective protein(s) are released from endothelial cells during P. aeruginosa infection. Mass spectrometry of endothelial cell culture media following P. aeruginosa infection allowed identification of multiple potential secreted modulators of Aβ, including cystatin C, gelsolin, and ApoJ/clusterin. Immunodepletion, co-immunoprecipitation, and ultracentrifugation determined that the cytoprotective factor released during infection of endothelial cells by P. aeruginosa is cystatin C, which appears to be in a complex with Aβ. Cytoprotective cystatin C may provide a novel therapeutic avenue for protection against the long-term consequences of infection with P. aeruginosa.
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Affiliation(s)
- Ron Balczon
- Department of Biochemistry and Molecular BiologyUniversity of South AlabamaMobileALUSA
- Center for Lung BiologyUniversity of South AlabamaMobileALUSA
| | - Kyle A. Morrow
- Department of Cell Biology and PhysiologyEdward Via College of Osteopathic MedicineMonroeLAUSA
| | - Silas Leavesley
- Center for Lung BiologyUniversity of South AlabamaMobileALUSA
- Department of Chemical and Biomedical EngineeringUniversity of South AlabamaMobileALUSA
| | - Christopher M. Francis
- Center for Lung BiologyUniversity of South AlabamaMobileALUSA
- Department of Physiology and Cell BiologyUniversity of South AlabamaMobileALUSA
| | - Trevor C. Stevens
- Center for Lung BiologyUniversity of South AlabamaMobileALUSA
- Department of Physiology and Cell BiologyUniversity of South AlabamaMobileALUSA
| | - Ezinne Agwaramgbo
- Department of Physiology and Cell BiologyUniversity of South AlabamaMobileALUSA
| | | | - Reece P. Stevens
- Center for Lung BiologyUniversity of South AlabamaMobileALUSA
- Department of Physiology and Cell BiologyUniversity of South AlabamaMobileALUSA
| | - Geri Langham
- Department of Physiology and Cell BiologyUniversity of South AlabamaMobileALUSA
| | - Sarah Voth
- Center for Lung BiologyUniversity of South AlabamaMobileALUSA
- Department of Physiology and Cell BiologyUniversity of South AlabamaMobileALUSA
| | - Eugene A. Cioffi
- Department of PharmacologyUniversity of South AlabamaMobileALUSA
| | - Susan E. Weintraub
- Department of Biochemistry and Structural Biology and Mass Spectrometry LaboratoryUniversity of Texas at San Antonio Health Sciences CenterTXUSA
| | - Troy Stevens
- Center for Lung BiologyUniversity of South AlabamaMobileALUSA
- Department of Physiology and Cell BiologyUniversity of South AlabamaMobileALUSA
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7
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Matanza XM, Osorio CR. Exposure of the Opportunistic Marine Pathogen Photobacterium damselae subsp. damselae to Human Body Temperature Is a Stressful Condition That Shapes the Transcriptome, Viability, Cell Morphology, and Virulence. Front Microbiol 2020; 11:1771. [PMID: 32849395 PMCID: PMC7396505 DOI: 10.3389/fmicb.2020.01771] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 07/06/2020] [Indexed: 01/21/2023] Open
Abstract
Photobacterium damselae subsp. damselae (Pdd), an important pathogen for marine animals, is also an opportunistic human pathogen that can cause fatal necrotizing fasciitis. The regulatory changes triggered by the temperature shift experienced by this marine pathogen upon entering the human body, are completely unknown. Here we report an RNA-seq approach combined with phenotypical assays to study the response of Pdd to cultivation at 37°C in comparison to 25°C. We found that cultivation of a Pdd highly virulent strain for fish and mice, RM-71, at 37°C, initially enhanced bacterial growth in comparison to 25°C as evidenced by the increase in optical density. However, cells were found to undergo a progressive loss of viability after 6 h cultivation at 37°C, and no viable cells could be detected from 30 h cultures at 37°C. In contrast, at 25°C, viable cell counts achieved the highest values at 30 h cultivation. Cells grown at 25°C showed normal rod morphology by scanning electron microscopy analysis whereas cells grown at 37°C exhibited chain-like structures and aberrant long shapes suggesting a defect in daughter cell separation and in septum formation. Cells grown at 37°C also exhibited reduced tolerance to benzylpenicillin. Using a RNA-seq approach we discovered that growth at 37°C triggered a heat-shock response, whereas genes involved in motility and virulence were repressed including iron acquisition systems, the type two secretion system, and damselysin toxin, a major virulence factor of Pdd. Human isolates did not exhibit advantage growing at 37°C compared to fish isolates, and comparative genomics did not reveal gene markers specific of human isolates, suggesting that any Pdd genotype existing in the marine environment might potentially cause disease in humans. Altogether, these data indicate that the potential of Pdd to cause disease in humans is an accidental condition rather than a selected trait, and that human body temperature constitutes a stressful condition for Pdd. This study provides the first transcriptome profile of Pdd exposed at human body temperature, and unveils a number of candidate molecular targets for prevention and control of human infections caused by this pathogen.
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Affiliation(s)
- Xosé M Matanza
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Carlos R Osorio
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
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8
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Pseudomonas aeruginosa Toxin ExoU as a Therapeutic Target in the Treatment of Bacterial Infections. Microorganisms 2019; 7:microorganisms7120707. [PMID: 31888268 PMCID: PMC6955817 DOI: 10.3390/microorganisms7120707] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 12/10/2019] [Accepted: 12/14/2019] [Indexed: 12/20/2022] Open
Abstract
The opportunistic pathogen Pseudomonas aeruginosa employs the type III secretion system (T3SS) and four effector proteins, ExoS, ExoT, ExoU, and ExoY, to disrupt cellular physiology and subvert the host’s innate immune response. Of the effector proteins delivered by the T3SS, ExoU is the most toxic. In P. aeruginosa infections, where the ExoU gene is expressed, disease severity is increased with poorer prognoses. This is considered to be due to the rapid and irreversible damage exerted by the phospholipase activity of ExoU, which cannot be halted before conventional antibiotics can successfully eliminate the pathogen. This review will discuss what is currently known about ExoU and explore its potential as a therapeutic target, highlighting some of the small molecule ExoU inhibitors that have been discovered from screening approaches.
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Springer TI, Reid TE, Gies SL, Feix JB. Interactions of the effector ExoU from Pseudomonas aeruginosa with short-chain phosphatidylinositides provide insights into ExoU targeting to host membranes. J Biol Chem 2019; 294:19012-19021. [PMID: 31662432 DOI: 10.1074/jbc.ra119.010278] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 10/21/2019] [Indexed: 12/25/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic multidrug-resistant pathogen and a common cause of infection in cystic fibrosis and ventilator-associated pneumonia and in burn and wound patients. P. aeruginosa uses its type III secretion system to secrete various effector proteins directly into mammalian host cells. ExoU is a potent type III secretion system effector that, after secretion, localizes to the inner cytoplasmic membrane of eukaryotic cells, where it exerts its phospholipase A2 activity upon interacting with ubiquitin and/or ubiquitinated proteins. In this study, we used site-directed spin-labeling electron paramagnetic resonance spectroscopy to examine the interaction of ExoU with soluble analogs of phosphatidylinositol (4,5)-bisphosphate (PI(4,5)P2). We found that dioctanoyl PI(4,5)P2 binds to and induces conformational changes in a C-terminal four-helix bundle (4HB) domain of ExoU implicated previously in membrane binding. Other soluble phosphoinositides also interacted with the 4HB but less effectively. Molecular modeling and ligand docking studies indicated the potential for numerous hydrogen bond interactions within and between interhelical loops of the 4HB and suggested several potential interaction sites for PI(4,5)P2 Site-directed mutagenesis experiments confirmed that the side chains of Gln-623 and Arg-661 play important roles in mediating PI(4,5)P2-induced conformational changes in ExoU. These results support a mechanism in which direct interactions with phosphatidylinositol-containing lipids play an essential role in targeting ExoU to host membrane bilayers. Molecules or peptides that block this interaction may prove useful in preventing the cytotoxic effects of ExoU to mitigate the virulence of P. aeruginosa strains that express this potent phospholipase toxin.
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Affiliation(s)
- Tzvia I Springer
- Department of Pharmaceutical Sciences, Concordia University Wisconsin, Mequon, Wisconsin 53097
| | - Terry-Elinor Reid
- Department of Pharmaceutical Sciences, Concordia University Wisconsin, Mequon, Wisconsin 53097
| | - Samantha L Gies
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Jimmy B Feix
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
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10
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Melo TG, Adesse D, Meirelles MDN, Pereira MCS. Trypanosoma cruzi down-regulates mechanosensitive proteins in cardiomyocytes. Mem Inst Oswaldo Cruz 2019; 114:e180593. [PMID: 31433004 PMCID: PMC6697411 DOI: 10.1590/0074-02760180593] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 07/08/2019] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Cardiac physiology depends on coupling and electrical and mechanical
coordination through the intercalated disc. Focal adhesions offer mechanical
support and signal transduction events during heart contraction-relaxation
processes. Talin links integrins to the actin cytoskeleton and serves as a
scaffold for the recruitment of other proteins, such as paxillin in focal
adhesion formation and regulation. Chagasic cardiomyopathy is caused by
infection by Trypanosoma cruzi and is a debilitating
condition comprising extensive fibrosis, inflammation, cardiac hypertrophy
and electrical alterations that culminate in heart failure. OBJECTIVES Since mechanotransduction coordinates heart function, we evaluated the
underlying mechanism implicated in the mechanical changes, focusing
especially in mechanosensitive proteins and related signalling pathways
during infection of cardiac cells by T. cruzi. METHODS We investigated the effect of T. cruzi infection on the
expression and distribution of talin/paxillin and associated proteins in
mouse cardiomyocytes in vitro by western blotting, immunofluorescence and
quantitative real-time polymerase chain reaction (qRT-PCR). FINDINGS Talin and paxillin spatial distribution in T.
cruzi-infected cardiomyocytes in vitro were
altered associated with a downregulation of these proteins and mRNAs levels
at 72 h post-infection (hpi). Additionally, we observed an increase in the
activation of the focal adhesion kinase (FAK) concomitant with increase in
β-1-integrin at 24 hpi. Finally, we detected a decrease in the activation of
FAK at 72 hpi in T. cruzi-infected cultures. MAIN CONCLUSION The results suggest that these changes may contribute to the
mechanotransduction disturbance evidenced in chagasic cardiomyopathy.
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Affiliation(s)
- Tatiana G Melo
- Fundação Oswaldo Cruz, Instituto Oswaldo Cruz, Laboratório de Ultraestrutura Celular, Rio de Janeiro, RJ, Brasil
| | - Daniel Adesse
- Fundação Oswaldo Cruz, Instituto Oswaldo Cruz, Laboratório de Biologia Estrutural, Rio de Janeiro, RJ, Brasil
| | - Maria de Nazareth Meirelles
- Fundação Oswaldo Cruz, Instituto Oswaldo Cruz, Laboratório de Ultraestrutura Celular, Rio de Janeiro, RJ, Brasil
| | - Mirian Claudia S Pereira
- Fundação Oswaldo Cruz, Instituto Oswaldo Cruz, Laboratório de Ultraestrutura Celular, Rio de Janeiro, RJ, Brasil
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11
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Phosphoinositides: multipurpose cellular lipids with emerging roles in cell death. Cell Death Differ 2019; 26:781-793. [PMID: 30742090 DOI: 10.1038/s41418-018-0269-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 12/18/2018] [Accepted: 12/19/2018] [Indexed: 02/07/2023] Open
Abstract
Phosphorylated phosphatidylinositol lipids, or phosphoinositides, critically regulate diverse cellular processes, including signalling transduction, cytoskeletal reorganisation, membrane dynamics and cellular trafficking. However, phosphoinositides have been inadequately investigated in the context of cell death, where they are mainly regarded as signalling secondary messengers. However, recent studies have begun to highlight the importance of phosphoinositides in facilitating cell death execution. Here, we cover the latest phosphoinositide research with a particular focus on phosphoinositides in the mechanisms of cell death. This progress article also raises key questions regarding the poorly defined role of phosphoinositides, particularly during membrane-associated events in cell death such as apoptosis and secondary necrosis. The review then further discusses important future directions for the phosphoinositide field, including therapeutically targeting phosphoinositides to modulate cell death.
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12
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Identification and Verification of Ubiquitin-Activated Bacterial Phospholipases. J Bacteriol 2019; 201:JB.00623-18. [PMID: 30455285 DOI: 10.1128/jb.00623-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 11/16/2018] [Indexed: 12/22/2022] Open
Abstract
ExoU is a potent type III secretion system effector that is injected directly into mammalian cells by the opportunistic pathogen Pseudomonas aeruginosa As a ubiquitin-activated phospholipase A2 (PLA2), ExoU exhibits cytotoxicity by cleaving membrane phospholipids, resulting in lysis of the host cells and inhibition of the innate immune response. Recently, ExoU has been established as a model protein for a group of ubiquitin-activated PLA2 enzymes encoded by a variety of bacteria. Bioinformatic analyses of homologous proteins is a powerful approach that can complement and enhance the overall understanding of protein structure and function. To conduct homology studies, it is important to have efficient and effective tools to screen and to validate the putative homologs of interest. Here we make use of an Escherichia coli-based dual expression system to screen putative ubiquitin-activated PLA2 enzymes from a variety of bacteria that are known to colonize humans and to cause human infections. The screen effectively identified multiple ubiquitin-activated phospholipases, which were validated using both biological and biochemical techniques. In this study, two new ExoU orthologs were identified and the ubiquitin activation of the rickettsial enzyme RP534 was verified. Conversely, ubiquitin was not found to regulate the activity of several other tested enzymes. Based on structural homology analyses, functional properties were predicted for AxoU, a unique member of the group expressed by Achromobacter xylosoxidans IMPORTANCE Bacterial phospholipases act as intracellular and extracellular enzymes promoting the destruction of phospholipid barriers and inflammation during infections. Identifying enzymes with a common mechanism of activation is an initial step in understanding structural and functional properties. These properties serve as critical information for the design of specific inhibitors to reduce enzymatic activity and ameliorate host cell death. In this study, we identify and verify cytotoxic PLA2 enzymes from several bacterial pathogens. Similar to the founding member of the group, ExoU, these enzymes share the property of ubiquitin-mediated activation. The identification and validation of potential toxins from multiple bacterial species provide additional proteins from which to derive structural insights that could lead to paninhibitors useful for treating a variety of infections.
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13
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Belyy A, Santecchia I, Renault L, Bourigault B, Ladant D, Mechold U. The extreme C terminus of the Pseudomonas aeruginosa effector ExoY is crucial for binding to its eukaryotic activator, F-actin. J Biol Chem 2018; 293:19785-19796. [PMID: 30377256 DOI: 10.1074/jbc.ra118.003784] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Revised: 10/22/2018] [Indexed: 12/25/2022] Open
Abstract
Bacterial nucleotidyl cyclase toxins are potent virulence factors that upon entry into eukaryotic cells are stimulated by endogenous cofactors to catalyze the production of large amounts of 3'5'-cyclic nucleoside monophosphates. The activity of the effector ExoY from Pseudomonas aeruginosa is stimulated by the filamentous form of actin (F-actin). Utilizing yeast phenotype analysis, site-directed mutagenesis, functional biochemical assays, and confocal microscopy, we demonstrate that the last nine amino acids of the C terminus of ExoY are crucial for the interaction with F-actin and, consequently, for ExoY's enzymatic activity in vitro and toxicity in a yeast model. We observed that isolated C-terminal sequences of P. aeruginosa ExoY that had been fused to a carrier protein bind to F-actin and that synthetic peptides corresponding to the extreme ExoY C terminus inhibit ExoY enzymatic activity in vitro and compete with the full-length enzyme for F-actin binding. Interestingly, we noted that various P. aeruginosa isolates of the PA14 family, including highly virulent strains, harbor ExoY variants with a mutation altering the C terminus of this effector. We found that these naturally occurring ExoY variants display drastically reduced enzymatic activity and toxicity. Our findings shed light on the molecular basis of the ExoY-F-actin interaction, revealing that the extreme C terminus of ExoY is critical for binding to F-actin in target cells and that some P. aeruginosa isolates carry C-terminally mutated, low-activity ExoY variants.
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Affiliation(s)
- Alexander Belyy
- From the Institut Pasteur, CNRS UMR 3528, Unité de Biochimie des Interactions Macromoléculaires, Département de Biologie Structurale et Chimie and
| | - Ignacio Santecchia
- Unité Biologie et Génétique de la Paroi Bactérienne, Département de Microbiologie, 75724 Paris cedex 15, France and
| | - Louis Renault
- the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette cedex, France
| | - Blandine Bourigault
- the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette cedex, France
| | - Daniel Ladant
- From the Institut Pasteur, CNRS UMR 3528, Unité de Biochimie des Interactions Macromoléculaires, Département de Biologie Structurale et Chimie and
| | - Undine Mechold
- From the Institut Pasteur, CNRS UMR 3528, Unité de Biochimie des Interactions Macromoléculaires, Département de Biologie Structurale et Chimie and
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Baker LY, Hobby CR, Siv AW, Bible WC, Glennon MS, Anderson DM, Symes SJ, Giles DK. Pseudomonas aeruginosa responds to exogenous polyunsaturated fatty acids (PUFAs) by modifying phospholipid composition, membrane permeability, and phenotypes associated with virulence. BMC Microbiol 2018; 18:117. [PMID: 30217149 PMCID: PMC6137939 DOI: 10.1186/s12866-018-1259-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 09/05/2018] [Indexed: 12/20/2022] Open
Abstract
Background Pseudomonas aeruginosa, a common opportunistic pathogen, is known to cause infections in a variety of compromised human tissues. An emerging mechanism for microbial survival is the incorporation of exogenous fatty acids to alter the cell’s membrane phospholipid profile. With these findings, we show that exogenous fatty acid exposure leads to changes in bacterial membrane phospholipid structure, membrane permeability, virulence phenotypes and consequent stress responses that may influence survival and persistence of Pseudomonas aeruginosa. Results Thin-layer chromatography and ultra performance liquid chromatography / ESI-mass spectrometry indicated alteration of bacterial phospholipid profiles following growth in the presence of polyunsaturated fatty acids (PUFAs) (ranging in carbon length and unsaturation). The exogenously supplied fatty acids were incorporated into the major bacterial phospholipids phosphatidylethanolamine and phosphatidylglycerol. The incorporation of fatty acids increased membrane permeability as judged by both accumulation and exclusion of ethidium bromide. Individual fatty acids were identified as modifying resistance to the cyclic peptide antibiotics polymyxin B and colistin, but not the beta-lactam imipenem. Biofilm formation was increased by several PUFAs and significant fluctuations in swimming motility were observed. Conclusions Our results emphasize the relevance and complexity of exogenous fatty acids in the membrane physiology and pathobiology of a medically important pathogen. P. aeruginosa exhibits versatility with regard to utilization of and response to exogenous fatty acids, perhaps revealing potential strategies for prevention and control of infection. Electronic supplementary material The online version of this article (10.1186/s12866-018-1259-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lyssa Y Baker
- Department of Biology, Geology, and Environmental Science, The University of Tennessee at Chattanooga, Chattanooga, TN, USA
| | - Chelsea R Hobby
- Department of Biology, Geology, and Environmental Science, The University of Tennessee at Chattanooga, Chattanooga, TN, USA
| | - Andrew W Siv
- Department of Biology, Geology, and Environmental Science, The University of Tennessee at Chattanooga, Chattanooga, TN, USA
| | - William C Bible
- Department of Biology, Geology, and Environmental Science, The University of Tennessee at Chattanooga, Chattanooga, TN, USA
| | - Michael S Glennon
- Department of Biology, Geology, and Environmental Science, The University of Tennessee at Chattanooga, Chattanooga, TN, USA
| | - Derek M Anderson
- Department of Chemistry and Physics, The University of Tennessee at Chattanooga, Chattanooga, TN, USA
| | - Steven J Symes
- Department of Chemistry and Physics, The University of Tennessee at Chattanooga, Chattanooga, TN, USA
| | - David K Giles
- Department of Biology, Geology, and Environmental Science, The University of Tennessee at Chattanooga, Chattanooga, TN, USA.
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15
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Feix JB, Kohn S, Tessmer MH, Anderson DM, Frank DW. Conformational Changes and Membrane Interaction of the Bacterial Phospholipase, ExoU: Characterization by Site-Directed Spin Labeling. Cell Biochem Biophys 2018; 77:79-87. [PMID: 30047043 DOI: 10.1007/s12013-018-0851-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 07/12/2018] [Indexed: 12/20/2022]
Abstract
Numerous pathogenic bacteria produce proteins evolved to facilitate their survival and dissemination by modifying the host environment. These proteins, termed effectors, often play a significant role in determining the virulence of the infection. Consequently, bacterial effectors constitute an important class of targets for the development of novel antibiotics. ExoU is a potent phospholipase effector produced by the opportunistic pathogen Pseudomonas aeruginosa. Previous studies have established that the phospholipase activity of ExoU requires non-covalent interaction with ubiquitin, however the molecular details of the mechanism of activation and the manner in which ExoU associates with a target lipid bilayer are not understood. In this review we describe our recent studies using site-directed spin labeling (SDSL) and EPR spectroscopy to elucidate the conformational changes and membrane interactions that accompany activation of ExoU. We find that ubiquitin binding and membrane interaction act synergistically to produce structural transitions that occur upon ExoU activation, and that the C-terminal four-helix bundle of ExoU functions as a phospholipid-binding domain, facilitating the association of ExoU with the membrane surface.
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Affiliation(s)
- Jimmy B Feix
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.
| | - Samantha Kohn
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Maxx H Tessmer
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - David M Anderson
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, 37232, USA
| | - Dara W Frank
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
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16
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Carda-Diéguez M, Ghai R, Rodríguez-Valera F, Amaro C. Wild eel microbiome reveals that skin mucus of fish could be a natural niche for aquatic mucosal pathogen evolution. MICROBIOME 2017; 5:162. [PMID: 29268781 PMCID: PMC5740887 DOI: 10.1186/s40168-017-0376-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 11/21/2017] [Indexed: 05/21/2023]
Abstract
BACKGROUND Fish skin mucosal surfaces (SMS) are quite similar in composition and function to some mammalian MS and, in consequence, could constitute an adequate niche for the evolution of mucosal aquatic pathogens in natural environments. We aimed to test this hypothesis by searching for metagenomic and genomic evidences in the SMS-microbiome of a model fish species (Anguilla Anguilla or eel), from different ecosystems (four natural environments of different water salinity and one eel farm) as well as the water microbiome (W-microbiome) surrounding the host. RESULTS Remarkably, potentially pathogenic Vibrio monopolized wild eel SMS-microbiome from natural ecosystems, Vibrio anguillarum/Vibrio vulnificus and Vibrio cholerae/Vibrio metoecus being the most abundant ones in SMS from estuary and lake, respectively. Functions encoded in the SMS-microbiome differed significantly from those in the W-microbiome and allowed us to predict that successful mucus colonizers should have specific genes for (i) attachment (mainly by forming biofilms), (ii) bacterial competence and communication, and (iii) resistance to mucosal innate immunity, predators (amoeba), and heavy metals/drugs. In addition, we found several mobile genetic elements (mainly integrative conjugative elements) as well as a series of evidences suggesting that bacteria exchange DNA in SMS. Further, we isolated and sequenced a V. metoecus strain from SMS. This isolate shares pathogenicity islands with V. cholerae O1 from intestinal infections that are absent in the rest of sequenced V. metoecus strains, all of them from water and extra-intestinal infections. CONCLUSIONS We have obtained metagenomic and genomic evidence in favor of the hypothesis on the role of fish mucosal surfaces as a specialized habitat selecting microbes capable of colonizing and persisting on other comparable mucosal surfaces, e.g., the human intestine.
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Affiliation(s)
- Miguel Carda-Diéguez
- Department of Microbiology and Ecology abd Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), University of Valencia, Valencia, Spain
| | - Rohit Ghai
- Institute of Hydrobiology, Department of Aquatic Microbial Ecology, Biology Center of the Academy of Sciences of the Czech Republic, České Budějovice, Czech Republic
| | - Francisco Rodríguez-Valera
- Evolutionary Genomics Group, Department de Producción Vegetal y Microbiología, Universidad Miguel Hernández, San Juan de Alicante, Spain
| | - Carmen Amaro
- Department of Microbiology and Ecology abd Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), University of Valencia, Valencia, Spain.
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17
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Phosphatidylinositol 4,5-Bisphosphate-Dependent Oligomerization of the Pseudomonas aeruginosa Cytotoxin ExoU. Infect Immun 2017; 86:IAI.00402-17. [PMID: 28993456 DOI: 10.1128/iai.00402-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 10/01/2017] [Indexed: 12/11/2022] Open
Abstract
The Pseudomonas aeruginosa type III secretion system delivers effector proteins directly into target cells, allowing the bacterium to modulate host cell functions. ExoU is the most cytotoxic of the known effector proteins and has been associated with more severe infections in humans. ExoU is a patatin-like A2 phospholipase requiring the cellular host factors phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and ubiquitin for its activation in vitro We demonstrated that PI(4,5)P2 also induces the oligomerization of ExoU and that this PI(4,5)P2-mediated oligomerization does not require ubiquitin. Single amino acid substitutions in the C-terminal membrane localization domain of ExoU reduced both its activity and its ability to form higher-order complexes in transfected cells and in vitro Combining inactive truncated ExoU proteins partially restored phospholipase activity and cytotoxicity, indicating that ExoU oligomerization may have functional significance. Our results indicate that PI(4,5)P2 induces the oligomerization of ExoU, which may be a mechanism by which this coactivator enhances the phospholipase activity of ExoU.
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18
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Zhang J, Wang Y, Guo H, Mao Z, Ge C. Identification and characterization of a phospholipase A1 activity type three secreted protein, PP_ExoU from Pseudomonas plecoglossicida NB2011, the causative agent of visceral granulomas disease in large yellow croaker (Larimichthys crocea). JOURNAL OF FISH DISEASES 2017; 40:831-840. [PMID: 27734506 DOI: 10.1111/jfd.12565] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Revised: 08/31/2016] [Accepted: 09/01/2016] [Indexed: 06/06/2023]
Abstract
Pseudomonas plecoglossicida NB2011, the causative agent of visceral granulomas disease in farmed Larimichthys crocea in China, encodes a predicted type three effector PP_ExoU, a homolog of the cytotoxin ExoU of Pseudomonas aeruginosa. In this study, secretion of PP_ExoU was tested in various broth, the protein was expressed with the pET30a prokaryotic system, the phospholipase A (PLA) activity of the recombinant protein was determined with fluorogenic phospholipid substrates, fusion expression with green fluorescent protein in transfected HeLa cells was investigated, and the lactate dehydrogenase (LDH) level was measured. The results showed the protein was type three secreted in several media; the recombinant protein displayed significant PLA1 activity with ubiquitin. Fluorescence was observed on the cell membrane and scattered in the cytoplasm of HeLa cells expressing catalytic wild-type PP_ExoU, blebbing and stretching developed in the cell membranes indicating of membrane damage. Fluorescence scattered in the cytoplasm of cells expressing the catalytic inactive protein. A significant LDH level was detected in HeLa cells expressing wild-type PP_exoU, but not in the Ser/Asp-mutated protein, suggestion mutation of predicted catalytic residues abolished the PLA activity. This is the first report on the function of a secreted type three protein from P. plecoglossicida.
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Affiliation(s)
- J Zhang
- Biological and Environmental College, Zhejiang Wanli University, Ningbo, China
| | - Y Wang
- Biological and Environmental College, Zhejiang Wanli University, Ningbo, China
| | - H Guo
- College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
| | - Z Mao
- Biological and Environmental College, Zhejiang Wanli University, Ningbo, China
| | - C Ge
- Biological and Environmental College, Zhejiang Wanli University, Ningbo, China
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19
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Torres IM, Demirdjian S, Vargas J, Goodale BC, Berwin B. Acidosis increases the susceptibility of respiratory epithelial cells to Pseudomonas aeruginosa-induced cytotoxicity. Am J Physiol Lung Cell Mol Physiol 2017; 313:L126-L137. [PMID: 28385813 DOI: 10.1152/ajplung.00524.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 03/16/2017] [Accepted: 03/31/2017] [Indexed: 12/21/2022] Open
Abstract
Bacterial infection can lead to acidosis of the local microenvironment, which is believed to exacerbate disease pathogenesis; however, the mechanisms by which changes in pH alter disease progression are poorly understood. We test the hypothesis that acidosis enhances respiratory epithelial cell death in response to infection with Pseudomonas aeruginosa Our findings support the idea that acidosis in the context of P. aeruginosa infection results in increased epithelial cell cytotoxicity due to ExoU intoxication. Importantly, enforced maintenance of neutral pH during P. aeruginosa infection demonstrates that cytotoxicity is dependent on the acidosis. Investigation of the underlying mechanisms revealed that host cell cytotoxicity correlated with increased bacterial survival during an acidic infection that was due to reduced bactericidal activity of host-derived antimicrobial peptides. These findings extend previous reports that the activities of antimicrobial peptides are pH-dependent and provide novel insights into the consequences of acidosis on infection-derived pathology. Therefore, this report provides the first evidence that physiological levels of acidosis increase the susceptibility of epithelial cells to acute Pseudomonas infection and demonstrates the benefit of maintaining pH homeostasis during a bacterial infection.
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Affiliation(s)
- Iviana M Torres
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire
| | - Sally Demirdjian
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire
| | - Jennifer Vargas
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire
| | - Britton C Goodale
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire
| | - Brent Berwin
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire
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20
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Tessmer MH, Anderson DM, Buchaklian A, Frank DW, Feix JB. Cooperative Substrate-Cofactor Interactions and Membrane Localization of the Bacterial Phospholipase A 2 (PLA 2) Enzyme, ExoU. J Biol Chem 2017; 292:3411-3419. [PMID: 28069812 DOI: 10.1074/jbc.m116.760074] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 01/05/2017] [Indexed: 11/06/2022] Open
Abstract
The ExoU type III secretion enzyme is a potent phospholipase A2 secreted by the Gram-negative opportunistic pathogen, Pseudomonas aeruginosa Activation of phospholipase activity is induced by protein-protein interactions with ubiquitin in the cytosol of a targeted eukaryotic cell, leading to destruction of host cell membranes. Previous work in our laboratory suggested that conformational changes within a C-terminal domain of the toxin might be involved in the activation mechanism. In this study, we use site-directed spin-labeling electron paramagnetic resonance spectroscopy to investigate conformational changes in a C-terminal four-helical bundle region of ExoU as it interacts with lipid substrates and ubiquitin, and to examine the localization of this domain with respect to the lipid bilayer. In the absence of ubiquitin or substrate liposomes, the overall structure of the C-terminal domain is in good agreement with crystallographic models derived from ExoU in complex with its chaperone, SpcU. Significant conformational changes are observed throughout the domain in the presence of ubiquitin and liposomes combined that are not observed with either liposomes or ubiquitin alone. In the presence of ubiquitin, two interhelical loops of the C-terminal four-helix bundle appear to penetrate the membrane bilayer, stabilizing ExoU-membrane association. Thus, ubiquitin and the substrate lipid bilayer act synergistically to induce a conformational rearrangement in the C-terminal domain of ExoU.
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Affiliation(s)
- Maxx H Tessmer
- Department of Microbiology and Molecular Genetics; Center for Infectious Disease Research
| | - David M Anderson
- Department of Microbiology and Molecular Genetics; Center for Infectious Disease Research
| | | | - Dara W Frank
- Department of Microbiology and Molecular Genetics; Center for Infectious Disease Research
| | - Jimmy B Feix
- Center for Infectious Disease Research; Department of Biophysics; National Biomedical EPR Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
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Chitinase 3-Like 1 (Chil1) Regulates Survival and Macrophage-Mediated Interleukin-1β and Tumor Necrosis Factor Alpha during Pseudomonas aeruginosa Pneumonia. Infect Immun 2016; 84:2094-2104. [PMID: 27141083 DOI: 10.1128/iai.00055-16] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 04/27/2016] [Indexed: 01/06/2023] Open
Abstract
Pseudomonas aeruginosa causes hospital-acquired pneumonia and is associated with high mortality. An effective response to such an infection includes efficient clearance of pathogenic organisms while limiting collateral damage from the host inflammatory response, known as host resistance and host tolerance, respectively. P. aeruginosa expresses a type III secretion system (T3SS) needle complex that induces NLRC4 (NOD-like receptor C4) activation, interleukin-1β (IL-1β) production, and host tissue damage. Chitinase 3-like-1 (Chil1) is expressed during infection and binds to its receptor, IL-13 receptor α2 (IL-13Rα2), to regulate the pathogen-host response during Streptococcus pneumoniae infection, but the role Chil1 plays in balancing the host resistance and host tolerance during P. aeruginosa pneumonia is not known. We conducted experiments using C57BL/6 mice with or without a genetic deficiency of Chil1 and demonstrated that Chil1-deficient mice succumb to P. aeruginosa infection more rapidly than the wild type (WT). The decreased survival time in infected Chil1-deficient mice is associated with more neutrophils recruited to the airways, more lung parenchymal damage, and increased pulmonary consolidation while maintaining equivalent bacterial killing compared to WT mice. Infected Chil1-deficient mice and bone marrow-derived macrophages (BMDMs) from Chil1-deficient mice have increased production of tumor necrosis factor alpha (TNF-α) and IL-1β compared to infected WT mice and macrophages. Infection of Chil1-deficient BMDMs with non-NLRC4-triggering P. aeruginosa, which is deficient in the T3SS needle complex, did not alter the excessive IL-1β production compared to BMDMs from WT mice. The addition of recombinant Chil1 decreases the excessive IL-1β production but only partially rescues stimulated BMDMs from IL-13Rα2-deficient mice. Our data provide mechanistic insights into how Chil1 regulates P. aeruginosa-induced host responses.
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22
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Abstract
Bacterial sphingomyelinases and phospholipases are a heterogeneous group of esterases which are usually surface associated or secreted by a wide variety of Gram-positive and Gram-negative bacteria. These enzymes hydrolyze sphingomyelin and glycerophospholipids, respectively, generating products identical to the ones produced by eukaryotic enzymes which play crucial roles in distinct physiological processes, including membrane dynamics, cellular signaling, migration, growth, and death. Several bacterial sphingomyelinases and phospholipases are essential for virulence of extracellular, facultative, or obligate intracellular pathogens, as these enzymes contribute to phagosomal escape or phagosomal maturation avoidance, favoring tissue colonization, infection establishment and progression, or immune response evasion. This work presents a classification proposal for bacterial sphingomyelinases and phospholipases that considers not only their enzymatic activities but also their structural aspects. An overview of the main physiopathological activities is provided for each enzyme type, as are examples in which inactivation of a sphingomyelinase- or a phospholipase-encoding gene impairs the virulence of a pathogen. The identification of sphingomyelinases and phospholipases important for bacterial pathogenesis and the development of inhibitors for these enzymes could generate candidate vaccines and therapeutic agents, which will diminish the impacts of the associated human and animal diseases.
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23
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Structural Basis of Lipid Targeting and Destruction by the Type V Secretion System of Pseudomonas aeruginosa. J Mol Biol 2016; 428:1790-803. [DOI: 10.1016/j.jmb.2016.03.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 03/05/2016] [Accepted: 03/14/2016] [Indexed: 11/15/2022]
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24
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Parker D, Ahn D, Cohen T, Prince A. Innate Immune Signaling Activated by MDR Bacteria in the Airway. Physiol Rev 2016; 96:19-53. [PMID: 26582515 DOI: 10.1152/physrev.00009.2015] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Health care-associated bacterial pneumonias due to multiple-drug resistant (MDR) pathogens are an important public health problem and are major causes of morbidity and mortality worldwide. In addition to antimicrobial resistance, these organisms have adapted to the milieu of the human airway and have acquired resistance to the innate immune clearance mechanisms that normally prevent pneumonia. Given the limited efficacy of antibiotics, bacterial clearance from the airway requires an effective immune response. Understanding how specific airway pathogens initiate and regulate innate immune signaling, and whether this response is excessive, leading to host-induced pathology may guide future immunomodulatory therapy. We will focus on three of the most important causes of health care-associated pneumonia, Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae, and review the mechanisms through which an inappropriate or damaging innate immune response is stimulated, as well as describe how airway pathogens cause persistent infection by evading immune activation.
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Affiliation(s)
- Dane Parker
- Departments of Pediatrics and Pharmacology, Columbia University, New York, New York
| | - Danielle Ahn
- Departments of Pediatrics and Pharmacology, Columbia University, New York, New York
| | - Taylor Cohen
- Departments of Pediatrics and Pharmacology, Columbia University, New York, New York
| | - Alice Prince
- Departments of Pediatrics and Pharmacology, Columbia University, New York, New York
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25
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Kondakova T, D'Heygère F, Feuilloley MJ, Orange N, Heipieper HJ, Duclairoir Poc C. Glycerophospholipid synthesis and functions in Pseudomonas. Chem Phys Lipids 2015; 190:27-42. [PMID: 26148574 DOI: 10.1016/j.chemphyslip.2015.06.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 06/29/2015] [Accepted: 06/30/2015] [Indexed: 11/25/2022]
Abstract
The genus Pseudomonas is one of the most heterogeneous groups of eubacteria, presents in all major natural environments and in wide range of associations with plants and animals. The wide distribution of these bacteria is due to the use of specific mechanisms to adapt to environmental modifications. Generally, bacterial adaptation is only considered under the aspect of genes and protein expression, but lipids also play a pivotal role in bacterial functioning and homeostasis. This review resumes the mechanisms and regulations of pseudomonal glycerophospholipid synthesis, and the roles of glycerophospholipids in bacterial metabolism and homeostasis. Recently discovered specific pathways of P. aeruginosa lipid synthesis indicate the lineage dependent mechanisms of fatty acids homeostasis. Pseudomonas glycerophospholipids ensure structure functions and play important roles in bacterial adaptation to environmental modifications. The lipidome of Pseudomonas contains a typical eukaryotic glycerophospholipid--phosphatidylcholine -, which is involved in bacteria-host interactions. The ability of Pseudomonas to exploit eukaryotic lipids shows specific and original strategies developed by these microorganisms to succeed in their infectious process. All compiled data provide the demonstration of the importance of studying the Pseudomonas lipidome to inhibit the infectious potential of these highly versatile germs.
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Affiliation(s)
- Tatiana Kondakova
- Normandie University of Rouen, Laboratory of Microbiology Signals and Microenvironment (LMSM), EA 4312, 55 rue St. Germain, 27000 Evreux, France
| | - François D'Heygère
- Centre de Biophysique Moléculaire, CNRS, UPR4301, rue Charles Sadron, 45071 Orléans, France
| | - Marc J Feuilloley
- Normandie University of Rouen, Laboratory of Microbiology Signals and Microenvironment (LMSM), EA 4312, 55 rue St. Germain, 27000 Evreux, France
| | - Nicole Orange
- Normandie University of Rouen, Laboratory of Microbiology Signals and Microenvironment (LMSM), EA 4312, 55 rue St. Germain, 27000 Evreux, France
| | - Hermann J Heipieper
- Department of Environmental Biotechnology, UFZ Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig, Germany
| | - Cécile Duclairoir Poc
- Normandie University of Rouen, Laboratory of Microbiology Signals and Microenvironment (LMSM), EA 4312, 55 rue St. Germain, 27000 Evreux, France.
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26
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Tyson GH, Halavaty AS, Kim H, Geissler B, Agard M, Satchell KJ, Cho W, Anderson WF, Hauser AR. A novel phosphatidylinositol 4,5-bisphosphate binding domain mediates plasma membrane localization of ExoU and other patatin-like phospholipases. J Biol Chem 2014; 290:2919-37. [PMID: 25505182 DOI: 10.1074/jbc.m114.611251] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Bacterial toxins require localization to specific intracellular compartments following injection into host cells. In this study, we examined the membrane targeting of a broad family of bacterial proteins, the patatin-like phospholipases. The best characterized member of this family is ExoU, an effector of the Pseudomonas aeruginosa type III secretion system. Upon injection into host cells, ExoU localizes to the plasma membrane, where it uses its phospholipase A2 activity to lyse infected cells. The targeting mechanism of ExoU is poorly characterized, but it was recently found to bind to the phospholipid phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), a marker for the plasma membrane of eukaryotic cells. We confirmed that the membrane localization domain (MLD) of ExoU had a direct affinity for PI(4,5)P2, and we determined that this binding was required for ExoU localization. Previously uncharacterized ExoU homologs from Pseudomonas fluorescens and Photorhabdus asymbiotica also localized to the plasma membrane and required PI(4,5)P2 for this localization. A conserved arginine within the MLD was critical for interaction of each protein with PI(4,5)P2 and for localization. Furthermore, we determined the crystal structure of the full-length P. fluorescens ExoU and found that it was similar to that of P. aeruginosa ExoU. Each MLD contains a four-helical bundle, with the conserved arginine exposed at its cap to allow for interaction with the negatively charged PI(4,5)P2. Overall, these findings provide a structural explanation for the targeting of patatin-like phospholipases to the plasma membrane and define the MLD of ExoU as a member of a new class of PI(4,5)P2 binding domains.
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Affiliation(s)
| | - Andrei S Halavaty
- Biochemistry and Center for Structural Genomics of Infectious Diseases, Northwestern University, Chicago, Illinois 60611 and
| | - Hyunjin Kim
- the Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607
| | | | | | | | - Wonhwa Cho
- the Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607
| | - Wayne F Anderson
- Biochemistry and Center for Structural Genomics of Infectious Diseases, Northwestern University, Chicago, Illinois 60611 and
| | - Alan R Hauser
- From the Departments of Microbiology-Immunology, Medicine, and
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Ubiquitin activates patatin-like phospholipases from multiple bacterial species. J Bacteriol 2014; 197:529-41. [PMID: 25404699 DOI: 10.1128/jb.02402-14] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Phospholipase A2 enzymes are ubiquitously distributed throughout the prokaryotic and eukaryotic kingdoms and are utilized in a wide array of cellular processes and physiological and immunological responses. Several patatin-like phospholipase homologs of ExoU from Pseudomonas aeruginosa were selected on the premise that ubiquitin activation of this class of bacterial enzymes was a conserved process. We found that ubiquitin activated all phospholipases tested in both in vitro and in vivo assays via a conserved serine-aspartate catalytic dyad. Ubiquitin chains versus monomeric ubiquitin were superior in inducing catalysis, and ubiquitin-like proteins failed to activate phospholipase activity. Toxicity studies in a prokaryotic dual-expression system grouped the enzymes into high- and low-toxicity classes. Toxicity measured in eukaryotic cells also suggested a two-tiered classification but was not predictive of the severity of cellular damage, suggesting that each enzyme may correspond to unique properties perhaps based on its specific biological function. Additional studies on lipid binding preference suggest that some enzymes in this family may be differentially sensitive to phosphatidyl-4,5-bisphosphate in terms of catalytic activation enhancement and binding affinity. Further analysis of the function and amino acid sequences of this enzyme family may lead to a useful approach to formulating a unifying model of how these phospholipases behave after delivery into the cytoplasmic compartment.
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