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Tao H, Zhou L, Yu D, Chen Y, Luo Y, Lin T. Effects of polystyrene microplastics on the metabolic level of Pseudomonas aeruginosa. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 922:171335. [PMID: 38423332 DOI: 10.1016/j.scitotenv.2024.171335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 02/22/2024] [Accepted: 02/26/2024] [Indexed: 03/02/2024]
Abstract
Given the widespread presence of Pseudomonas aeruginosa in water and its threat to human health, the metabolic changes in Pseudomonas aeruginosa when exposed to polystyrene microplastics (PS-MPs) exposure were studied, focusing on molecular level. Through non-targeted metabolomics, a total of 64 differential metabolites were screened out under positive ion mode and 44 under negative ion mode. The content of bacterial metabolites changed significantly, primarily involving lipids, nucleotides, amino acids, and organic acids. Heightened intracellular oxidative damage led to a decrease in lipid molecules and nucleotide-related metabolites. The down-regulation of amino acid metabolites, such as L-Glutamic and L-Proline, highlighted disruptions in cellular energy metabolism and the impaired ability to synthesize proteins as a defense against oxidation. The impact of PS-MPs on organic acid metabolism was evident in the inhibition of pyruvate and citrate, thereby disrupting the cells' normal participation in energy cycles. The integration of Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that PS-MPs mainly caused changes in metabolic pathways, including ABC transporters, Aminoacyl-tRNA biosynthesis, Purine metabolism, Glycerophospholipid metabolism and TCA cycle in Pseudomonas aeruginosa. Most of the differential metabolites enriched in these pathways were down-regulated, demonstrating that PS-MPs hindered the expression of metabolic pathways, ultimately impairing the ability of cells to synthesize proteins, DNA, and RNA. This disruption affected cell proliferation and information transduction, thus hampering energy circulation and inhibiting cell growth. Findings of this study supplemented the toxic effects of microplastics and the defense mechanisms of microorganisms, in turn safeguarding drinking water safety and human health.
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Affiliation(s)
- Hui Tao
- Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China.
| | - Lingqin Zhou
- Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China
| | - Duo Yu
- Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China
| | - Yiyang Chen
- Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China
| | - Yunxin Luo
- Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China
| | - Tao Lin
- Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China
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Kho ZY, Azad MAK, Zhu Y, Han ML, Zhou QT, Velkov T, Naderer T, Li J. Transcriptomic interplay between Acinetobacter baumannii , human macrophage and polymyxin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.23.576770. [PMID: 38328180 PMCID: PMC10849618 DOI: 10.1101/2024.01.23.576770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Optimization of antibiotic therapy has been hindered by our dearth of understanding on the mechanism of the host-pathogen-drug interactions. Here, we employed dual RNA-sequencing to examine transcriptomic perturbations in response to polymyxin B in a co-culture infection model of Acinetobacter baumannii and human macrophages. Our findings revealed that polymyxin B treatment induced significant transcriptomic response in macrophage-interacting A. baumannii , exacerbating bacterial oxidative stress, disrupting metal homeostasis, affecting osmoadaptation, triggering stringent stress response, and influencing pathogenic factors. Moreover, infected macrophages adapt heme catabolism, coagulation cascade, and hypoxia-inducible signaling to confront bacterial invasion. Disrupting rcnB , ompW , and traR/dksA genes in A. baumannii impairs metal homeostasis, osmotic stress defense and stringent responses, thereby enhancing antibacterial killing by polymyxin. These findings shed light on the global stress adaptations at the network level during host-pathogen-drug interactions, revealing promising therapeutic targets for further investigation. IMPORTANCE In the context of the development of bacterial resistance during the course of antibiotic therapy, the role of macrophages in shaping bacterial response to antibiotic killing remains enigmatic. Herein we employed dual RNA-sequencing and an in vitro tripartite model to delve into the unexplored transcriptional networks of the Acinetobacter baumannii -macrophage-polymyxin axis. Our findings uncovered the potential synergy between macrophages and polymyxin B which appear to act in co-operation to disrupt multiple stress tolerance mechanisms in A. baumannii . Notably, we discovered the critical roles of bacterial nickel/cobalt homeostasis ( rcnB family), osmotic stress defense ( ompW family), and stringent response regulator ( traR/dksA C4-type zinc finger) in tolerating the last-line antibiotic polymyxin B. Our findings may lead to potential targets for the development of novel therapeutics against the problematic pathogen A. baumannii .
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Sánchez-Jiménez A, Llamas MA, Marcos-Torres FJ. Transcriptional Regulators Controlling Virulence in Pseudomonas aeruginosa. Int J Mol Sci 2023; 24:11895. [PMID: 37569271 PMCID: PMC10418997 DOI: 10.3390/ijms241511895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 07/21/2023] [Accepted: 07/22/2023] [Indexed: 08/13/2023] Open
Abstract
Pseudomonas aeruginosa is a pathogen capable of colonizing virtually every human tissue. The host colonization competence and versatility of this pathogen are powered by a wide array of virulence factors necessary in different steps of the infection process. This includes factors involved in bacterial motility and attachment, biofilm formation, the production and secretion of extracellular invasive enzymes and exotoxins, the production of toxic secondary metabolites, and the acquisition of iron. Expression of these virulence factors during infection is tightly regulated, which allows their production only when they are needed. This process optimizes host colonization and virulence. In this work, we review the intricate network of transcriptional regulators that control the expression of virulence factors in P. aeruginosa, including one- and two-component systems and σ factors. Because inhibition of virulence holds promise as a target for new antimicrobials, blocking the regulators that trigger the production of virulence determinants in P. aeruginosa is a promising strategy to fight this clinically relevant pathogen.
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Affiliation(s)
| | - María A. Llamas
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain;
| | - Francisco Javier Marcos-Torres
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain;
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Pukale DD, Lazarenko D, Aryal SR, Khabaz F, Shriver LP, Leipzig ND. Osmotic Contribution of Synthesized Betaine by Choline Dehydrogenase Using In Vivo and In Vitro Models of Post-traumatic Syringomyelia. Cell Mol Bioeng 2023; 16:41-54. [PMID: 36660584 PMCID: PMC9842837 DOI: 10.1007/s12195-022-00749-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 10/27/2022] [Indexed: 11/28/2022] Open
Abstract
Introduction Syringomyelia (SM) is a debilitating spinal cord disorder in which a cyst, or syrinx, forms in the spinal cord parenchyma due to congenital and acquired causes. Over time syrinxes expand and elongate, which leads to compressing the neural tissues and a mild to severe range of symptoms. In prior omics studies, significant upregulation of betaine and its synthesis enzyme choline dehydrogenase (CHDH) were reported during syrinx formation/expansion in SM injured spinal cords, but the role of betaine regulation in SM etiology remains unclear. Considering betaine's known osmoprotectant role in biological systems, along with antioxidant and methyl donor activities, this study aimed to better understand osmotic contributions of synthesized betaine by CHDH in response to SM injuries in the spinal cord. Methods A post-traumatic SM (PTSM) rat model and in vitro cellular models using rat astrocytes and HepG2 liver cells were utilized to investigate the role of betaine synthesis by CHDH. Additionally, the osmotic contributions of betaine were evaluated using a combination of experimental as well as simulation approaches. Results In the PTSM injured spinal cord CHDH expression was observed in cells surrounding syrinxes. We next found that rat astrocytes and HepG2 cells were capable of synthesizing betaine via CHDH under osmotic stress in vitro to maintain osmoregulation. Finally, our experimental and simulation approaches showed that betaine was capable of directly increasing meaningful osmotic pressure. Conclusions The findings from this study demonstrate new evidence that CHDH activity in the spinal cord provides locally synthesized betaine for osmoregulation in SM pathophysiology. Supplementary Information The online version of this article contains supplementary material available 10.1007/s12195-022-00749-5.
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Affiliation(s)
- Dipak D. Pukale
- Department of Chemical, Biomolecular, and Corrosion Engineering, University of Akron, Akron, OH 44325 USA
| | - Daria Lazarenko
- School of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325 USA
| | - Siddhartha R. Aryal
- Department of Biomedical Engineering, The University of Akron, Akron, OH 44325 USA
| | - Fardin Khabaz
- Department of Chemical, Biomolecular, and Corrosion Engineering, University of Akron, Akron, OH 44325 USA
- School of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325 USA
| | - Leah P. Shriver
- Department of Chemistry, Washington University, Saint Louis, MO 63130 USA
- Department of Medicine, Washington University, Saint Louis, MO 63130 USA
- Center for Metabolomics and Isotope Tracing, Washington University, Saint Louis, MO 63130 USA
| | - Nic D. Leipzig
- Department of Chemical, Biomolecular, and Corrosion Engineering, University of Akron, Akron, OH 44325 USA
- Department of Biomedical Engineering, The University of Akron, Akron, OH 44325 USA
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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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Serral F, Pardo AM, Sosa E, Palomino MM, Nicolás MF, Turjanski AG, Ramos PIP, Fernández Do Porto D. Pathway Driven Target Selection in Klebsiella pneumoniae: Insights Into Carbapenem Exposure. Front Cell Infect Microbiol 2022; 12:773405. [PMID: 35174104 PMCID: PMC8841789 DOI: 10.3389/fcimb.2022.773405] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 01/07/2022] [Indexed: 12/13/2022] Open
Abstract
Carbapenem-resistant Klebsiella pneumoniae (CR-KP) represents an emerging threat to public health. CR-KP infections result in elevated morbidity and mortality. This fact, coupled with their global dissemination and increasingly limited number of therapeutic options, highlights the urgency of novel antimicrobials. Innovative strategies linking genome-wide interrogation with multi-layered metabolic data integration can accelerate the early steps of drug development, particularly target selection. Using the BioCyc ontology, we generated and manually refined a metabolic network for a CR-KP, K. pneumoniae Kp13. Converted into a reaction graph, we conducted topological-based analyses in this network to prioritize pathways exhibiting druggable features and fragile metabolic points likely exploitable to develop novel antimicrobials. Our results point to the aptness of previously recognized pathways, such as lipopolysaccharide and peptidoglycan synthesis, and casts light on the possibility of targeting less explored cellular functions. These functions include the production of lipoate, trehalose, glycine betaine, and flavin, as well as the salvaging of methionine. Energy metabolism pathways emerged as attractive targets in the context of carbapenem exposure, targeted either alone or in conjunction with current therapeutic options. These results prompt further experimental investigation aimed at controlling this highly relevant pathogen.
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Affiliation(s)
- Federico Serral
- Instituto de Cálculo, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (UBA), Buenos Aires, Argentina
| | - Agustin M. Pardo
- Instituto de Cálculo, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (UBA), Buenos Aires, Argentina
| | - Ezequiel Sosa
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - María Mercedes Palomino
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
- Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Universidad de Buenos Aires, Cdad. Universitaria, Buenos Aires, Argentina
| | - Marisa F. Nicolás
- Laboratório de Bioinformática (LABINFO), Laboratório Nacional de Computação Científica (LNCC), Petrópolis, Brazil
| | - Adrian G. Turjanski
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
- Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Universidad de Buenos Aires, Cdad. Universitaria, Buenos Aires, Argentina
| | - Pablo Ivan P. Ramos
- Centro de Integração de Dados e Conhecimentos para a Saúde (CIDACS), Instituto Gonçalo Moniz, Fundação Oswaldo Cruz (Fiocruz - Bahia), Salvador, Brazil
- *Correspondence: Darío Fernández Do Porto, ; Pablo Ivan P. Ramos,
| | - Darío Fernández Do Porto
- Instituto de Cálculo, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (UBA), Buenos Aires, Argentina
- Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Universidad de Buenos Aires, Cdad. Universitaria, Buenos Aires, Argentina
- *Correspondence: Darío Fernández Do Porto, ; Pablo Ivan P. Ramos,
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Monturiol-Gross L, Villalta-Romero F, Flores-Díaz M, Alape-Girón A. Bacterial phospholipases C with dual activity: phosphatidylcholinesterase and sphingomyelinase. FEBS Open Bio 2021; 11:3262-3275. [PMID: 34709730 PMCID: PMC8634861 DOI: 10.1002/2211-5463.13320] [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: 09/14/2021] [Revised: 10/25/2021] [Accepted: 10/27/2021] [Indexed: 02/06/2023] Open
Abstract
Bacterial phospholipases and sphingomyelinases are lipolytic esterases that are structurally and evolutionarily heterogeneous. These enzymes play crucial roles as virulence factors in several human and animal infectious diseases. Some bacterial phospholipases C (PLCs) have both phosphatidylcholinesterase and sphingomyelinase C activities. Among them, Listeria
monocytogenes PlcB, Clostridium perfringens PLC, and Pseudomonas aeruginosa PlcH are the most deeply understood. In silico predictions of substrates docking with these three bacterial enzymes provide evidence that they interact with different substrates at the same active site. This review discusses structural aspects, substrate specificity, and the mechanism of action of those bacterial enzymes on target cells and animal infection models to shed light on their roles in pathogenesis.
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Affiliation(s)
- Laura Monturiol-Gross
- Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica
| | - Fabian Villalta-Romero
- Centro de Investigación en Biotecnología, Escuela de Biología, Instituto Tecnológico de Costa Rica, Cartago, Costa Rica
| | - Marietta Flores-Díaz
- Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica
| | - Alberto Alape-Girón
- Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica.,Departamento de Bioquímica, Escuela de Medicina, Universidad de Costa Rica, San José, Costa Rica
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Pukale DD, Farrag M, Gudneppanavar R, Baumann HJ, Konopka M, Shriver LP, Leipzig ND. Osmoregulatory Role of Betaine and Betaine/γ-Aminobutyric Acid Transporter 1 in Post-Traumatic Syringomyelia. ACS Chem Neurosci 2021; 12:3567-3578. [PMID: 34550670 DOI: 10.1021/acschemneuro.1c00056] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Syringomyelia (SM) is primarily characterized by the formation of a fluid-filled cyst that forms in the parenchyma of the spinal cord following injury or other pathology. Recent omics studies in animal models have identified dysregulation of solute carriers, channels, transporters, and small molecules associated with osmolyte regulation during syrinx formation/expansion in the spinal cord. However, their connections to syringomyelia etiology are poorly understood. In this study, the biological functions of the potent osmolyte betaine and its associated solute carrier betaine/γ-aminobutyric acid (GABA) transporter 1 (BGT1) were studied in SM. First, a rat post-traumatic SM model was used to demonstrate that the BGT1 was primarily expressed in astrocytes in the vicinity of syrinxes. In an in vitro system, we found that astrocytes uptake betaine through BGT1 to regulate cell size under hypertonic conditions. Treatment with BGT1 inhibitors, especially NNC 05-2090, demonstrated midhigh micromolar range potency in vitro that reversed the osmoprotective effects of betaine. Finally, the specificity of these BGT1 inhibitors in the CNS was demonstrated in vivo, suggesting feasibility for targeting betaine transport in SM. In summary, these data provide an enhanced understanding of the role of betaine and its associated solute carrier BGT1 in cell osmoregulation and implicates the active role of betaine and BGT1 in syringomyelia progression.
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Affiliation(s)
- Dipak D. Pukale
- Department of Chemical, Biomolecular, and Corrosion Engineering, University of Akron, Akron, Ohio 44325, United States
| | - Mahmoud Farrag
- Integrated Biosciences Program, University of Akron, Akron, Ohio 44325, United States
| | | | - Hannah J. Baumann
- Department of Chemistry, University of Akron, Akron, Ohio 44325, United States
| | - Michael Konopka
- Department of Chemistry, University of Akron, Akron, Ohio 44325, United States
| | - Leah P. Shriver
- Integrated Biosciences Program, University of Akron, Akron, Ohio 44325, United States
- Department of Chemistry, University of Akron, Akron, Ohio 44325, United States
| | - Nic D. Leipzig
- Department of Chemical, Biomolecular, and Corrosion Engineering, University of Akron, Akron, Ohio 44325, United States
- Integrated Biosciences Program, University of Akron, Akron, Ohio 44325, United States
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Mavrodi OV, McWilliams JR, Peter JO, Berim A, Hassan KA, Elbourne LDH, LeTourneau MK, Gang DR, Paulsen IT, Weller DM, Thomashow LS, Flynt AS, Mavrodi DV. Root Exudates Alter the Expression of Diverse Metabolic, Transport, Regulatory, and Stress Response Genes in Rhizosphere Pseudomonas. Front Microbiol 2021; 12:651282. [PMID: 33936009 PMCID: PMC8079746 DOI: 10.3389/fmicb.2021.651282] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 03/08/2021] [Indexed: 12/20/2022] Open
Abstract
Plants live in association with microorganisms that positively influence plant development, vigor, and fitness in response to pathogens and abiotic stressors. The bulk of the plant microbiome is concentrated belowground at the plant root-soil interface. Plant roots secrete carbon-rich rhizodeposits containing primary and secondary low molecular weight metabolites, lysates, and mucilages. These exudates provide nutrients for soil microorganisms and modulate their affinity to host plants, but molecular details of this process are largely unresolved. We addressed this gap by focusing on the molecular dialog between eight well-characterized beneficial strains of the Pseudomonas fluorescens group and Brachypodium distachyon, a model for economically important food, feed, forage, and biomass crops of the grass family. We collected and analyzed root exudates of B. distachyon and demonstrated the presence of multiple carbohydrates, amino acids, organic acids, and phenolic compounds. The subsequent screening of bacteria by Biolog Phenotype MicroArrays revealed that many of these metabolites provide carbon and energy for the Pseudomonas strains. RNA-seq profiling of bacterial cultures amended with root exudates revealed changes in the expression of genes encoding numerous catabolic and anabolic enzymes, transporters, transcriptional regulators, stress response, and conserved hypothetical proteins. Almost half of the differentially expressed genes mapped to the variable part of the strains’ pangenome, reflecting the importance of the variable gene content in the adaptation of P. fluorescens to the rhizosphere lifestyle. Our results collectively reveal the diversity of cellular pathways and physiological responses underlying the establishment of mutualistic interactions between these beneficial rhizobacteria and their plant hosts.
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Affiliation(s)
- Olga V Mavrodi
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Janiece R McWilliams
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Jacob O Peter
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Anna Berim
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
| | - Karl A Hassan
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW, Australia
| | - Liam D H Elbourne
- Department of Molecular Sciences, Macquarie University, Sydney, NSW, Australia
| | - Melissa K LeTourneau
- USDA Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA, United States
| | - David R Gang
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
| | - Ian T Paulsen
- Department of Molecular Sciences, Macquarie University, Sydney, NSW, Australia
| | - David M Weller
- USDA Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA, United States
| | - Linda S Thomashow
- USDA Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA, United States
| | - Alex S Flynt
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Dmitri V Mavrodi
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
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A High-Throughput Method for Identifying Novel Genes That Influence Metabolic Pathways Reveals New Iron and Heme Regulation in Pseudomonas aeruginosa. mSystems 2021; 6:6/1/e00933-20. [PMID: 33531406 PMCID: PMC7857532 DOI: 10.1128/msystems.00933-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The ability to simultaneously and more directly correlate genes with metabolite levels on a global level would provide novel information for many biological platforms yet has thus far been challenging. Here, we describe a method to help address this problem, which we dub “Met-Seq” (metabolite-coupled Tn sequencing). Heme is an essential metabolite for most life on earth. Bacterial pathogens almost universally require iron to infect a host, often acquiring this nutrient in the form of heme. The Gram-negative pathogen Pseudomonas aeruginosa is no exception, where heme acquisition and metabolism are known to be crucial for both chronic and acute infections. To unveil unknown genes and pathways that could play a role with heme metabolic flux in this pathogen, we devised an omic-based approach we dubbed “Met-Seq,” for metabolite-coupled transposon sequencing. Met-Seq couples a biosensor with fluorescence-activated cell sorting (FACS) and massively parallel sequencing, allowing for direct identification of genes associated with metabolic changes. In this work, we first construct and validate a heme biosensor for use with P. aeruginosa and exploit Met-Seq to identify 188 genes that potentially influence intracellular heme levels. Identified genes largely consisted of metabolic pathways not previously associated with heme, including many secreted virulence effectors, as well as 11 predicted small RNAs (sRNAs) and riboswitches whose functions are not currently understood. We verify that five Met-Seq hits affect intracellular heme levels; a predicted extracytoplasmic function (ECF) factor, a phospholipid acquisition system, heme biosynthesis regulator Dnr, and two predicted antibiotic monooxygenase (ABM) domains of unknown function (PA0709 and PA3390). Finally, we demonstrate that PA0709 and PA3390 are novel heme-binding proteins. Our data suggest that Met-Seq could be extrapolated to other biological systems and metabolites for which there is an available biosensor, and provides a new template for further exploration of iron/heme regulation and metabolism in P. aeruginosa and other pathogens. IMPORTANCE The ability to simultaneously and more directly correlate genes with metabolite levels on a global level would provide novel information for many biological platforms yet has thus far been challenging. Here, we describe a method to help address this problem, which we dub “Met-Seq” (metabolite-coupled Tn sequencing). Met-Seq uses the powerful combination of fluorescent biosensors, fluorescence-activated cell sorting (FACS), and next-generation sequencing (NGS) to rapidly identify genes that influence the levels of specific intracellular metabolites. For proof of concept, we create and test a heme biosensor and then exploit Met-Seq to identify novel genes involved in the regulation of heme in the pathogen Pseudomonas aeruginosa. Met-Seq-generated data were largely comprised of genes which have not previously been reported to influence heme levels in this pathogen, two of which we verify as novel heme-binding proteins. As heme is a required metabolite for host infection in P. aeruginosa and most other pathogens, our studies provide a new list of targets for potential antimicrobial therapies and shed additional light on the balance between infection, heme uptake, and heme biosynthesis.
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11
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Gregory GJ, Boyd EF. Stressed out: Bacterial response to high salinity using compatible solute biosynthesis and uptake systems, lessons from Vibrionaceae. Comput Struct Biotechnol J 2021; 19:1014-1027. [PMID: 33613867 PMCID: PMC7876524 DOI: 10.1016/j.csbj.2021.01.030] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 01/18/2021] [Accepted: 01/20/2021] [Indexed: 12/19/2022] Open
Abstract
Bacteria have evolved mechanisms that allow them to adapt to changes in osmolarity and some species have adapted to live optimally in high salinity environments such as in the marine ecosystem. Most bacteria that live in high salinity do so by the biosynthesis and/or uptake of compatible solutes, small organic molecules that maintain the turgor pressure of the cell. Osmotic stress response mechanisms and their regulation among marine heterotrophic bacteria are poorly understood. In this review, we discuss what is known about compatible solute metabolism and transport and new insights gained from studying marine bacteria belonging to the family Vibrionaceae.
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Affiliation(s)
| | - E. Fidelma Boyd
- Corresponding author at: Department of Biological Sciences, 341 Wolf Hall, University of Delaware, Newark, DE 19716, United States.
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12
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Lee SG, Harline K, Abar O, Akadri SO, Bastian AG, Chen HYS, Duan M, Focht CM, Groziak AR, Kao J, Kottapalli JS, Leong MC, Lin JJ, Liu R, Luo JE, Meyer CM, Mo AF, Pahng SH, Penna V, Raciti CD, Srinath A, Sudhakar S, Tang JD, Cox BR, Holland CK, Cascella B, Cruz W, McClerkin SA, Kunkel BN, Jez JM. The plant pathogen enzyme AldC is a long-chain aliphatic aldehyde dehydrogenase. J Biol Chem 2020; 295:13914-13926. [PMID: 32796031 DOI: 10.1074/jbc.ra120.014747] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 08/11/2020] [Indexed: 12/13/2022] Open
Abstract
Aldehyde dehydrogenases are versatile enzymes that serve a range of biochemical functions. Although traditionally considered metabolic housekeeping enzymes because of their ability to detoxify reactive aldehydes, like those generated from lipid peroxidation damage, the contributions of these enzymes to other biological processes are widespread. For example, the plant pathogen Pseudomonas syringae strain PtoDC3000 uses an indole-3-acetaldehyde dehydrogenase to synthesize the phytohormone indole-3-acetic acid to elude host responses. Here we investigate the biochemical function of AldC from PtoDC3000. Analysis of the substrate profile of AldC suggests that this enzyme functions as a long-chain aliphatic aldehyde dehydrogenase. The 2.5 Å resolution X-ray crystal of the AldC C291A mutant in a dead-end complex with octanal and NAD+ reveals an apolar binding site primed for aliphatic aldehyde substrate recognition. Functional characterization of site-directed mutants targeting the substrate- and NAD(H)-binding sites identifies key residues in the active site for ligand interactions, including those in the "aromatic box" that define the aldehyde-binding site. Overall, this study provides molecular insight for understanding the evolution of the prokaryotic aldehyde dehydrogenase superfamily and their diversity of function.
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Affiliation(s)
- Soon Goo Lee
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA; Department of Chemistry and Biochemistry, University of North Carolina-Wilmington, Wilmington, North Carolina, USA
| | - Kate Harline
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Orchid Abar
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Sakirat O Akadri
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Alexander G Bastian
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Hui-Yuan S Chen
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Michael Duan
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Caroline M Focht
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Amanda R Groziak
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Jesse Kao
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | | | - Matthew C Leong
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Joy J Lin
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Regina Liu
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Joanna E Luo
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Christine M Meyer
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Albert F Mo
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Seong Ho Pahng
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Vinay Penna
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Chris D Raciti
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Abhinav Srinath
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Shwetha Sudhakar
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Joseph D Tang
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Brian R Cox
- Department of Chemistry and Biochemistry, University of North Carolina-Wilmington, Wilmington, North Carolina, USA
| | - Cynthia K Holland
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA; Department of Biology, Williams College, Williamstown, Massachusetts, USA
| | - Barrie Cascella
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Wilhelm Cruz
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Sheri A McClerkin
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA; Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois, USA
| | - Barbara N Kunkel
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Joseph M Jez
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA.
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13
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Pham VD, To TA, Gagné-Thivierge C, Couture M, Lagüe P, Yao D, Picard MÈ, Lortie LA, Attéré SA, Zhu X, Levesque RC, Charette SJ, Shi R. Structural insights into the putative bacterial acetylcholinesterase ChoE and its substrate inhibition mechanism. J Biol Chem 2020; 295:8708-8724. [PMID: 32371400 PMCID: PMC7324521 DOI: 10.1074/jbc.ra119.011809] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 05/04/2020] [Indexed: 01/01/2023] Open
Abstract
Mammalian acetylcholinesterase (AChE) is well-studied, being important in both cholinergic brain synapses and the peripheral nervous systems and also a key drug target for many diseases. In contrast, little is known about the structures and molecular mechanism of prokaryotic acetylcholinesterases. We report here the structural and biochemical characterization of ChoE, a putative bacterial acetylcholinesterase from Pseudomonas aeruginosa Analysis of WT and mutant strains indicated that ChoE is indispensable for P. aeruginosa growth with acetylcholine as the sole carbon and nitrogen source. The crystal structure of ChoE at 1.35 Å resolution revealed that this enzyme adopts a typical fold of the SGNH hydrolase family. Although ChoE and eukaryotic AChEs catalyze the same reaction, their overall structures bear no similarities constituting an interesting example of convergent evolution. Among Ser-38, Asp-285, and His-288 of the catalytic triad residues, only Asp-285 was not essential for ChoE activity. Combined with kinetic analyses of WT and mutant proteins, multiple crystal structures of ChoE complexed with substrates, products, or reaction intermediate revealed the structural determinants for substrate recognition, snapshots of the various catalytic steps, and the molecular basis of substrate inhibition at high substrate concentrations. Our results indicate that substrate inhibition in ChoE is due to acetate release being blocked by the binding of a substrate molecule in a nonproductive mode. Because of the distinct overall folds and significant differences of the active site between ChoE and eukaryotic AChEs, these structures will serve as a prototype for other prokaryotic acetylcholinesterases.
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Affiliation(s)
- Van Dung Pham
- Département de Biochimie, de Microbiologie et de Bio-informatique, Université Laval, Québec, Canada; Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada; PROTEO, the Québec Network for Research on Protein Function, Engineering, and Applications, Québec, Canada
| | - Tuan Anh To
- Département de Biochimie, de Microbiologie et de Bio-informatique, Université Laval, Québec, Canada; Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada; PROTEO, the Québec Network for Research on Protein Function, Engineering, and Applications, Québec, Canada
| | - Cynthia Gagné-Thivierge
- Département de Biochimie, de Microbiologie et de Bio-informatique, Université Laval, Québec, Canada; Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Hôpital Laval, Québec, Canada
| | - Manon Couture
- Département de Biochimie, de Microbiologie et de Bio-informatique, Université Laval, Québec, Canada; Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada; PROTEO, the Québec Network for Research on Protein Function, Engineering, and Applications, Québec, Canada
| | - Patrick Lagüe
- Département de Biochimie, de Microbiologie et de Bio-informatique, Université Laval, Québec, Canada; Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada; PROTEO, the Québec Network for Research on Protein Function, Engineering, and Applications, Québec, Canada
| | - Deqiang Yao
- iHuman Institute, ShanghaiTech University, Shanghai, P.R. China
| | - Marie-Ève Picard
- Département de Biochimie, de Microbiologie et de Bio-informatique, Université Laval, Québec, Canada; Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada; PROTEO, the Québec Network for Research on Protein Function, Engineering, and Applications, Québec, Canada
| | - Louis-André Lortie
- Département de Biochimie, de Microbiologie et de Bio-informatique, Université Laval, Québec, Canada
| | - Sabrina A Attéré
- Département de Biochimie, de Microbiologie et de Bio-informatique, Université Laval, Québec, Canada; Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Hôpital Laval, Québec, Canada
| | - Xiaojun Zhu
- Département de Biochimie, de Microbiologie et de Bio-informatique, Université Laval, Québec, Canada; Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada; PROTEO, the Québec Network for Research on Protein Function, Engineering, and Applications, Québec, Canada
| | - Roger C Levesque
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada
| | - Steve J Charette
- Département de Biochimie, de Microbiologie et de Bio-informatique, Université Laval, Québec, Canada; Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Hôpital Laval, Québec, Canada
| | - Rong Shi
- Département de Biochimie, de Microbiologie et de Bio-informatique, Université Laval, Québec, Canada; Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada; PROTEO, the Québec Network for Research on Protein Function, Engineering, and Applications, Québec, Canada.
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14
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Choline–betaine pathway contributes to hyperosmotic stress and subsequent lethal stress resistance in Pseudomonas protegens SN15-2. J Biosci 2020. [DOI: 10.1007/s12038-020-00060-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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15
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Pan X, Fan Z, Chen L, Liu C, Bai F, Wei Y, Tian Z, Dong Y, Shi J, Chen H, Jin Y, Cheng Z, Jin S, Lin J, Wu W. PvrA is a novel regulator that contributes to Pseudomonas aeruginosa pathogenesis by controlling bacterial utilization of long chain fatty acids. Nucleic Acids Res 2020; 48:5967-5985. [PMID: 32406921 PMCID: PMC7293031 DOI: 10.1093/nar/gkaa377] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 04/28/2020] [Accepted: 04/30/2020] [Indexed: 12/19/2022] Open
Abstract
During infection of a host, Pseudomonas aeruginosa orchestrates global gene expression to adapt to the host environment and counter the immune attacks. P. aeruginosa harbours hundreds of regulatory genes that play essential roles in controlling gene expression. However, their contributions to the bacterial pathogenesis remain largely unknown. In this study, we analysed the transcriptomic profile of P. aeruginosa cells isolated from lungs of infected mice and examined the roles of upregulated regulatory genes in bacterial virulence. Mutation of a novel regulatory gene pvrA (PA2957) attenuated the bacterial virulence in an acute pneumonia model. Chromatin immunoprecipitation (ChIP)-Seq and genetic analyses revealed that PvrA directly regulates genes involved in phosphatidylcholine utilization and fatty acid catabolism. Mutation of the pvrA resulted in defective bacterial growth when phosphatidylcholine or palmitic acid was used as the sole carbon source. We further demonstrated that palmitoyl coenzyme A is a ligand for the PvrA, enhancing the binding affinity of PvrA to its target promoters. An arginine residue at position 136 was found to be essential for PvrA to bind palmitoyl coenzyme A. Overall, our results revealed a novel regulatory pathway that controls genes involved in phosphatidylcholine and fatty acid utilization and contributes to the bacterial virulence.
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Affiliation(s)
- Xiaolei Pan
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Zheng Fan
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Lei Chen
- Department of Plant Biology and Ecology, College of Life Science Nankai University, Tianjin 300071 China
| | - Chang Liu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Fang Bai
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Yu Wei
- State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Tianjin 300071, China
| | - Zhenyang Tian
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Yuanyuan Dong
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Jing Shi
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Hao Chen
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Yongxin Jin
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Zhihui Cheng
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Shouguang Jin
- Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Jianping Lin
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
- State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Tianjin 300071, China
| | - Weihui Wu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
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16
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Breisch J, Averhoff B. Identification of osmo-dependent and osmo-independent betaine-choline-carnitine transporters in Acinetobacter baumannii: role in osmostress protection and metabolic adaptation. Environ Microbiol 2020; 22:2724-2735. [PMID: 32219961 DOI: 10.1111/1462-2920.14998] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 03/22/2020] [Indexed: 12/28/2022]
Abstract
Acinetobacter baumannii is outstanding for its ability to cope with low water activities and therefore its adaptation mechanism to osmotic stress. Here we report on the identification and characterization of five different secondary active compatible solute transporters, belonging to the betaine-choline-carnitine transporter (BCCT) family. Our studies revealed two choline-specific and three glycine betaine-specific BCCTs. Activity of the BCCTs was differentially dependent to the osmolality: one choline and one betaine transporter were osmostress-independent. Addition of choline to resting cells of Acinetobacter grown in the presence of the co-substrate choline or with phosphatidylcholine as sole carbon source led to ATP synthesis in the wild type but not in the BCCT quadruple mutant. This indicates that the BCCTs are essential to transport the energy substrate choline. The role of the different BCCTs in osmostress resistance and in metabolic adaptation of A. baumannii to the human host is discussed.
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Affiliation(s)
- Jennifer Breisch
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Germany
| | - Beate Averhoff
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Germany
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17
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High-resolution in situ transcriptomics of Pseudomonas aeruginosa unveils genotype independent patho-phenotypes in cystic fibrosis lungs. Nat Commun 2018; 9:3459. [PMID: 30150613 PMCID: PMC6110831 DOI: 10.1038/s41467-018-05944-5] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 07/30/2018] [Indexed: 12/30/2022] Open
Abstract
Life-long bacterial infections in cystic fibrosis (CF) airways constitute an excellent model both for persistent infections and for microbial adaptive evolution in complex dynamic environments. Using high-resolution transcriptomics applied on CF sputum, we profile transcriptional phenotypes of Pseudomonas aeruginosa populations in patho-physiological conditions. Here we show that the soft-core genome of genetically distinct populations, while maintaining transcriptional flexibility, shares a common expression program tied to the lungs environment. We identify genetically independent traits defining P. aeruginosa physiology in vivo, documenting the connection between several previously identified mutations in CF isolates and some of the convergent phenotypes known to develop in later stages of the infection. In addition, our data highlight to what extent this organism can exploit its extensive repertoire of physiological pathways to acclimate to a new niche and suggest how alternative nutrients produced in the lungs may be utilized in unexpected metabolic contexts.
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18
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Pulmonary Surfactant Promotes Virulence Gene Expression and Biofilm Formation in Klebsiella pneumoniae. Infect Immun 2018; 86:IAI.00135-18. [PMID: 29712730 DOI: 10.1128/iai.00135-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 04/24/2018] [Indexed: 12/18/2022] Open
Abstract
The interactions between Klebsiella pneumoniae and the host environment at the site of infection are largely unknown. Pulmonary surfactant serves as an initial point of contact for inhaled bacteria entering the lung and is thought to contain molecular cues that aid colonization and pathogenesis. To gain insight into this ecological transition, we characterized the transcriptional response of K. pneumoniae MGH 78578 to purified pulmonary surfactant. This work revealed changes within the K. pneumoniae transcriptome that likely contribute to host colonization, adaptation, and virulence in vivo Notable transcripts expressed under these conditions include genes involved in capsule synthesis, lipopolysaccharide modification, antibiotic resistance, biofilm formation, and metabolism. In addition, we tested the contributions of other surfactant-induced transcripts to K. pneumoniae survival using engineered isogenic KPPR1 deletion strains in a murine model of acute pneumonia. In these infection studies, we identified the MdtJI polyamine efflux pump and the ProU glycine betaine ABC transporter to be significant mediators of K. pneumoniae survival within the lung and confirmed previous evidence for the importance of de novo leucine synthesis to bacterial survival during infection. Finally, we determined that pulmonary surfactant promoted type 3 fimbria-mediated biofilm formation in K. pneumoniae and identified two surfactant constituents, phosphatidylcholine and cholesterol, that drive this response. This study provides novel insight into the interactions occurring between K. pneumoniae and the host at an important infection site and demonstrates the utility of purified lung surfactant preparations for dissecting host-lung pathogen interactions in vitro.
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19
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Transcriptional Responses of Pseudomonas aeruginosa to Potable Water and Freshwater. Appl Environ Microbiol 2018; 84:AEM.02350-17. [PMID: 29305509 DOI: 10.1128/aem.02350-17] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 01/01/2018] [Indexed: 02/03/2023] Open
Abstract
Many Pseudomonas aeruginosa infections are derived from residential, recreational, or surface water sources; thus, these environments represent an important preinfection niche. To better understand P. aeruginosa biology in these environments, we quantified transcriptional changes by microarray after exposure to diluted LB, diluted R2B, potable tap water, and freshwater from a eutrophic pond. Quantitative reverse transcription-PCR (qRT-PCR) confirmed the conservation of these responses in other water sources, and competition experiments were used to test the importance of three implicated metabolic pathways. The global transcriptional responses in potable water and freshwater showed strong induction of genes involved in metabolism of the head groups and acyl tails of phospholipids, as well as nucleotide metabolism, with commensurate decreased transcript expression of genes encoding their synthetic pathways. These data suggest that phospholipids and nucleotides are part of the nutritional milieu of these two environments. A unique response in municipal-delivered potable water was to the metals in the piping system, particularly copper. To identify potential nutrient sources used by P. aeruginosa in these environments, we used competition assays between the wild-type and deletion mutant strains in three pathways induced under these conditions. For phospholipid head-group metabolism, ethanolamine utilization (eutB) was important for competition in potable water, while choline oxidation (betBA) was important for competition in freshwater. Nucleotide utilization, particularly pyrimidine metabolism (dht), showed a trend toward importance in freshwater but was not statistically significant. These findings provide new insights into the P. aeruginosa response to potable water and freshwater and led to the identification of potentially important nutrient sources in these environments.IMPORTANCE Much of our knowledge about Pseudomonas aeruginosa comes from the infection niche, and much less is known about its lifestyle in the environment. P. aeruginosa is an adaptable bacterium capable of growing in many environments but is particularly common in potable water systems and freshwater. We used the transcriptional responses of P. aeruginosa to these environments to identify important nutrient sources specific to either of these two environments. Additionally, these environments could provide experimental situations to understand gene function for the large number of transcripts with unknown functions induced under these conditions.
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20
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Scott RA, Thilmony R, Harden LA, Zhou Y, Brandl MT. Escherichia coli O157:H7 Converts Plant-Derived Choline to Glycine Betaine for Osmoprotection during Pre- and Post-harvest Colonization of Injured Lettuce Leaves. Front Microbiol 2017; 8:2436. [PMID: 29276506 PMCID: PMC5727454 DOI: 10.3389/fmicb.2017.02436] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Accepted: 11/23/2017] [Indexed: 11/26/2022] Open
Abstract
Plant injury is inherent to the production and processing of fruit and vegetables. The opportunistic colonization of damaged plant tissue by human enteric pathogens may contribute to the occurrence of outbreaks of foodborne illness linked to produce. Escherichia coli O157:H7 (EcO157) responds to physicochemical stresses in cut lettuce and lettuce lysates by upregulation of several stress response pathways. We investigated the tolerance of EcO157 to osmotic stress imposed by the leakage of osmolytes from injured lettuce leaf tissue. LC-MS analysis of bacterial osmoprotectants in lettuce leaf lysates and wound washes indicated an abundant natural pool of choline, but sparse quantities of glycine betaine and proline. Glycine betaine was a more effective osmoprotectant than choline in EcO157 under osmotic stress conditions in vitro. An EcO157 mutant with a deletion of the betTIBA genes, which are required for biosynthesis of glycine betaine from imported choline, achieved population sizes twofold lower than those of the parental strain (P < 0.05) over the first hour of colonization of cut lettuce in modified atmosphere packaging (MAP). The cell concentrations of the betTIBA mutant also were 12-fold lower than those of the parental strain (P < 0.01) when grown in hypertonic lettuce lysate, indicating that lettuce leaf cellular contents provide choline for osmoprotection of EcO157. To demonstrate the utilization of available choline by EcO157 for osmoadaptation in injured leaf tissue, deuterated (D-9) choline was introduced to wound sites in MAP lettuce; LC-MS analysis revealed the conversion of D9-choline to D-9 glycine betaine in the parental strain, but no significant amounts were observed in the betTIBA mutant. The EcO157 ΔbetTIBA-ΔotsBA double mutant, which is additionally deficient in de novo synthesis of the compatible solute trehalose, was significantly less fit than the parental strain after their co-inoculation onto injured lettuce leaves and MAP cut lettuce. However, its competitive fitness followed a different time-dependent trend in MAP lettuce, likely due to differences in O2 content, which modulates betTIBA expression. Our study demonstrates that damaged lettuce leaf tissue does not merely supply EcO157 with substrates for proliferation, but also provides the pathogen with choline for its survival to osmotic stress experienced at the site of injury.
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Affiliation(s)
- Russell A. Scott
- Produce Safety and Microbiology Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA, United States
| | - Roger Thilmony
- Crop Improvement and Genetics Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA, United States
| | - Leslie A. Harden
- Produce Safety and Microbiology Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA, United States
| | - Yaguang Zhou
- Produce Safety and Microbiology Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA, United States
| | - Maria T. Brandl
- Produce Safety and Microbiology Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA, United States
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21
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Sánchez DG, Primo ED, Damiani MT, Lisa AT. Pseudomonas aeruginosa gbdR gene is transcribed from a σ54-dependent promoter under the control of NtrC/CbrB, IHF and BetI. MICROBIOLOGY-SGM 2017; 163:1343-1354. [PMID: 28791946 DOI: 10.1099/mic.0.000502] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Pseudomonasaeruginosa uses choline as a source of carbon and nitrogen, and also for the synthesis of glycine betaine, an osmoprotectant under stress conditions such as drought and salinity. The transcription factor GbdR is the specific regulator of choline metabolism and it belongs to the Arac/XylS family of transcriptional regulators. Despite the link between choline catabolism and bacterial pathogenicity, gbdR regulation has not been explored in detail. In the present work, we describe how gbdR transcription can be initiated from a σ54-dependent promoter. gbdR transcription can be activated by NtrC in the absence of a preferential nitrogen source, by CbrB in the absence of a preferential carbon source, and by the integration host factor favouring DNA bending. In addition, we found that BetI negatively regulates gbdR expression in the absence of choline. We identified two overlapping BetI binding sites in the gbdR promoter sequence, providing an additional example of σ54-promoter down-regulation. Based on our findings, we propose a model for gdbR regulation and its impact on choline metabolism.
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Affiliation(s)
- Diego Germán Sánchez
- Laboratory of Phagocytosis and Intracellular Transport, School of Medicine, University of Cuyo, IHEM-CONICET, Mendoza 5500, Argentina.,Department of Molecular Biology, FCEFQN, National University of Río Cuarto, Route 36-Km 601, 5800, Argentina
| | - Emiliano David Primo
- Department of Molecular Biology, FCEFQN, National University of Río Cuarto, Route 36-Km 601, 5800, Argentina
| | - María Teresa Damiani
- Laboratory of Phagocytosis and Intracellular Transport, School of Medicine, University of Cuyo, IHEM-CONICET, Mendoza 5500, Argentina
| | - Angela Teresita Lisa
- Department of Molecular Biology, FCEFQN, National University of Río Cuarto, Route 36-Km 601, 5800, Argentina
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Fozo EM, Rucks EA. The Making and Taking of Lipids: The Role of Bacterial Lipid Synthesis and the Harnessing of Host Lipids in Bacterial Pathogenesis. Adv Microb Physiol 2016; 69:51-155. [PMID: 27720012 DOI: 10.1016/bs.ampbs.2016.07.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In order to survive environmental stressors, including those induced by growth in the human host, bacterial pathogens will adjust their membrane physiology accordingly. These physiological changes also include the use of host-derived lipids to alter their own membranes and feed central metabolic pathways. Within the host, the pathogen is exposed to many stressful stimuli. A resulting adaptation is for pathogens to scavenge the host environment for readily available lipid sources. The pathogen takes advantage of these host-derived lipids to increase or decrease the rigidity of their own membranes, to provide themselves with valuable precursors to feed central metabolic pathways, or to impact host signalling and processes. Within, we review the diverse mechanisms that both extracellular and intracellular pathogens employ to alter their own membranes as well as their use of host-derived lipids in membrane synthesis and modification, in order to increase survival and perpetuate disease within the human host. Furthermore, we discuss how pathogen employed mechanistic utilization of host-derived lipids allows for their persistence, survival and potentiation of disease. A more thorough understanding of all of these mechanisms will have direct consequences for the development of new therapeutics, and specifically, therapeutics that target pathogens, while preserving normal flora.
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Affiliation(s)
- E M Fozo
- University of Tennessee, Knoxville, TN, United States.
| | - E A Rucks
- Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States.
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23
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Choline Catabolism in Burkholderia thailandensis Is Regulated by Multiple Glutamine Amidotransferase 1-Containing AraC Family Transcriptional Regulators. J Bacteriol 2016; 198:2503-14. [PMID: 27381916 PMCID: PMC4999938 DOI: 10.1128/jb.00372-16] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 06/30/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Burkholderia thailandensis is a soil-dwelling bacterium that shares many metabolic pathways with the ecologically similar, but evolutionarily distant, Pseudomonas aeruginosa Among the diverse nutrients it can utilize is choline, metabolizable to the osmoprotectant glycine betaine and subsequently catabolized as a source of carbon and nitrogen, similar to P. aeruginosa Orthologs of genes in the choline catabolic pathway in these two bacteria showed distinct differences in gene arrangement as well as an additional orthologous transcriptional regulator in B. thailandensis In this study, we showed that multiple glutamine amidotransferase 1 (GATase 1)-containing AraC family transcription regulators (GATRs) are involved in regulation of the B. thailandensis choline catabolic pathway (gbdR1, gbdR2, and souR). Using genetic analyses and sequencing the transcriptome in the presence and absence of choline, we identified the likely regulons of gbdR1 (BTH_II1869) and gbdR2 (BTH_II0968). We also identified a functional ortholog for P. aeruginosa souR, a GATR that regulates the metabolism of sarcosine to glycine. GbdR1 is absolutely required for expression of the choline catabolic locus, similar to P. aeruginosa GbdR, while GbdR2 is important to increase expression of the catabolic locus. Additionally, the B. thailandensis SouR ortholog (BTH_II0994) is required for catabolism of choline and its metabolites as carbon sources, whereas in P. aeruginosa, SouR function can by bypassed by GbdR. The strategy employed by B. thailandensis represents a distinct regulatory solution to control choline catabolism and thus provides both an evolutionary counterpoint and an experimental system to analyze the acquisition and regulation of this pathway during environmental growth and infection. IMPORTANCE Many proteobacteria that occupy similar environmental niches have horizontally acquired orthologous genes for metabolism of compounds useful in their shared environment. The arrangement and differential regulation of these components can help us understand both the evolution of these systems and the potential roles these pathways have in the biology of each bacterium. Here, we describe the transcriptome response of Burkholderia thailandensis to the eukaryote-enriched molecule choline, identify the regulatory pathway governing choline catabolism, and compare the pathway to that previously described for Pseudomonas aeruginosa These data support a multitiered regulatory network in B. thailandensis, with conserved orthologs in the select agents Burkholderia pseudomallei and Burkholderia mallei, as well as the opportunistic lung pathogens in the Burkholderia cepacia clade.
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Sun L, Li JQ, Ren N, Qi H, Dong F, Xiao J, Xu F, Jiao WW, Shen C, Song WQ, Shen AD. Utility of Novel Plasma Metabolic Markers in the Diagnosis of Pediatric Tuberculosis: A Classification and Regression Tree Analysis Approach. J Proteome Res 2016; 15:3118-25. [PMID: 27451809 DOI: 10.1021/acs.jproteome.6b00228] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Although tuberculosis (TB) has been the greatest killer due to a single infectious disease, pediatric TB is still hard to diagnose because of the lack of sensitive biomarkers. Metabolomics is increasingly being applied in infectious diseases. But little is known regarding metabolic biomarkers in children with TB. A combination of a NMR-based plasma metabolic method and classification and regression tree (CART) analysis was used to provide a broader range of applications in TB diagnosis in our study. Plasma samples obtained from 28 active TB children and 37 non-TB controls (including 21 RTIs and 16 healthy children) were analyzed by an orthogonal partial least-squares discriminant analysis (OPLS-DA) model, and 17 metabolites were identified that can separate children with TB from non-TB controls. CART analysis was then used to choose 3 of the markers, l-valine, pyruvic acid, and betaine, with the least error. The sensitivity, specificity, and area under the curve (AUC) of the 3 metabolites is 85.7% (24/28, 95% CI, 66.4%, 95.3%), 94.6% (35/37, 95% CI, 80.5%, 99.1%), and 0.984(95% CI, 0.917, 1.000), respectively. The 3 metabolites demonstrated sensitivity of 82.4% (14/17, 95% CI, 55.8%, 95.3%) and specificity of 83.9% (26/31, 95% CI, 65.5%, 93.9%), respectively, in 48 blinded subjects in an independent cohort. Taken together, the novel plasma metabolites are potentially useful for diagnosis of pediatric TB and would provide insights into the disease mechanism.
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Affiliation(s)
- Lin Sun
- Key Laboratory of Major Diseases in Children, Ministry of Education, National Key Discipline of Pediatrics (Capital Medical University), Beijing Key Laboratory of Pediatric Respiratory Infection Diseases, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University , 100045 Beijing, People's Republic of China
| | - Jie-Qiong Li
- Key Laboratory of Major Diseases in Children, Ministry of Education, National Key Discipline of Pediatrics (Capital Medical University), Beijing Key Laboratory of Pediatric Respiratory Infection Diseases, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University , 100045 Beijing, People's Republic of China
| | - Na Ren
- Key Laboratory of Major Diseases in Children, Ministry of Education, National Key Discipline of Pediatrics (Capital Medical University), Beijing Key Laboratory of Pediatric Respiratory Infection Diseases, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University , 100045 Beijing, People's Republic of China
| | - Hui Qi
- Key Laboratory of Major Diseases in Children, Ministry of Education, National Key Discipline of Pediatrics (Capital Medical University), Beijing Key Laboratory of Pediatric Respiratory Infection Diseases, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University , 100045 Beijing, People's Republic of China
| | - Fang Dong
- Key Laboratory of Major Diseases in Children, Ministry of Education, National Key Discipline of Pediatrics (Capital Medical University), Beijing Key Laboratory of Pediatric Respiratory Infection Diseases, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University , 100045 Beijing, People's Republic of China
| | - Jing Xiao
- Key Laboratory of Major Diseases in Children, Ministry of Education, National Key Discipline of Pediatrics (Capital Medical University), Beijing Key Laboratory of Pediatric Respiratory Infection Diseases, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University , 100045 Beijing, People's Republic of China
| | - Fang Xu
- Key Laboratory of Major Diseases in Children, Ministry of Education, National Key Discipline of Pediatrics (Capital Medical University), Beijing Key Laboratory of Pediatric Respiratory Infection Diseases, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University , 100045 Beijing, People's Republic of China
| | - Wei-Wei Jiao
- Key Laboratory of Major Diseases in Children, Ministry of Education, National Key Discipline of Pediatrics (Capital Medical University), Beijing Key Laboratory of Pediatric Respiratory Infection Diseases, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University , 100045 Beijing, People's Republic of China
| | - Chen Shen
- Key Laboratory of Major Diseases in Children, Ministry of Education, National Key Discipline of Pediatrics (Capital Medical University), Beijing Key Laboratory of Pediatric Respiratory Infection Diseases, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University , 100045 Beijing, People's Republic of China
| | - Wen-Qi Song
- Key Laboratory of Major Diseases in Children, Ministry of Education, National Key Discipline of Pediatrics (Capital Medical University), Beijing Key Laboratory of Pediatric Respiratory Infection Diseases, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University , 100045 Beijing, People's Republic of China
| | - A-Dong Shen
- Key Laboratory of Major Diseases in Children, Ministry of Education, National Key Discipline of Pediatrics (Capital Medical University), Beijing Key Laboratory of Pediatric Respiratory Infection Diseases, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University , 100045 Beijing, People's Republic of China
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25
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Reen FJ, Flynn S, Woods DF, Dunphy N, Chróinín MN, Mullane D, Stick S, Adams C, O'Gara F. Bile signalling promotes chronic respiratory infections and antibiotic tolerance. Sci Rep 2016; 6:29768. [PMID: 27432520 PMCID: PMC4949476 DOI: 10.1038/srep29768] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 06/17/2016] [Indexed: 12/29/2022] Open
Abstract
Despite aggressive antimicrobial therapy, many respiratory pathogens persist in the lung, underpinning the chronic inflammation and eventual lung decline that are characteristic of respiratory disease. Recently, bile acid aspiration has emerged as a major comorbidity associated with a range of lung diseases, shaping the lung microbiome and promoting colonisation by Pseudomonas aeruginosa in Cystic Fibrosis (CF) patients. In order to uncover the molecular mechanism through which bile modulates the respiratory microbiome, a combination of global transcriptomic and phenotypic analyses of the P. aeruginosa response to bile was undertaken. Bile responsive pathways responsible for virulence, adaptive metabolism, and redox control were identified, with macrolide and polymyxin antibiotic tolerance increased significantly in the presence of bile. Bile acids, and chenodeoxycholic acid (CDCA) in particular, elicited chronic biofilm behaviour in P. aeruginosa, while induction of the pro-inflammatory cytokine Interleukin-6 (IL-6) in lung epithelial cells by CDCA was Farnesoid X Receptor (FXR) dependent. Microbiome analysis of paediatric CF sputum samples demonstrated increased colonisation by P. aeruginosa and other Proteobacterial pathogens in bile aspirating compared to non-aspirating patients. Together, these data suggest that bile acid signalling is a leading trigger for the development of chronic phenotypes underlying the pathophysiology of chronic respiratory disease.
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Affiliation(s)
- F Jerry Reen
- BIOMERIT Research Centre, School of Microbiology, University College Cork, National University of Ireland, Cork, Ireland
| | - Stephanie Flynn
- BIOMERIT Research Centre, School of Microbiology, University College Cork, National University of Ireland, Cork, Ireland
| | - David F Woods
- BIOMERIT Research Centre, School of Microbiology, University College Cork, National University of Ireland, Cork, Ireland
| | - Niall Dunphy
- BIOMERIT Research Centre, School of Microbiology, University College Cork, National University of Ireland, Cork, Ireland
| | | | - David Mullane
- Paediatric Cystic Fibrosis Unit, Cork University Hospital, Cork, Ireland
| | | | - Claire Adams
- BIOMERIT Research Centre, School of Microbiology, University College Cork, National University of Ireland, Cork, Ireland
| | - Fergal O'Gara
- BIOMERIT Research Centre, School of Microbiology, University College Cork, National University of Ireland, Cork, Ireland.,Telethon Kids Institute, Perth, Western Australia.,School of Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, WA 6102, Australia
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26
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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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27
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Metabolism and Pathogenicity of Pseudomonas aeruginosa Infections in the Lungs of Individuals with Cystic Fibrosis. Microbiol Spectr 2016; 3. [PMID: 26350318 DOI: 10.1128/microbiolspec.mbp-0003-2014] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Individuals with the genetic disease cystic fibrosis (CF) accumulate mucus or sputum in their lungs. This sputum is a potent growth substrate for a range of potential pathogens, and the opportunistic bacterium Pseudomonas aeruginosa is generally most difficult of these to eradicate. As a result, P. aeruginosa infections are frequently maintained in the CF lung throughout life, and are the leading cause of death for these individuals. While great effort has been expended to better understand and treat these devastating infections, only recently have researchers begun to rigorously examine the roles played by specific nutrients in CF sputum to cue P. aeruginosa pathogenicity. This chapter summarizes the current state of knowledge regarding how P. aeruginosa metabolism in CF sputum affects initiation and maintenance of these infections. It contains an overview of CF lung disease and the mechanisms of P. aeruginosa pathogenicity. Several model systems used to study these infections are described with emphasis on the challenge of replicating the chronic infections observed in humans with CF. Nutrients present in CF sputum are surveyed, and the impacts of these nutrients on the infection are discussed. The chapter concludes by addressing the future of this line of research including the use of next-generation technologies and the potential for metabolism-based therapeutics.
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28
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Molina L, Udaondo Z, Duque E, Fernández M, Bernal P, Roca A, de la Torre J, Ramos JL. Specific Gene Loci of Clinical Pseudomonas putida Isolates. PLoS One 2016; 11:e0147478. [PMID: 26820467 PMCID: PMC4731212 DOI: 10.1371/journal.pone.0147478] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 01/05/2016] [Indexed: 11/18/2022] Open
Abstract
Pseudomonas putida are ubiquitous inhabitants of soils and clinical isolates of this species have been seldom described. Clinical isolates show significant variability in their ability to cause damage to hosts because some of them are able to modulate the host’s immune response. In the current study, comparisons between the genomes of different clinical and environmental strains of P. putida were done to identify genetic clusters shared by clinical isolates that are not present in environmental isolates. We show that in clinical strains specific genes are mostly present on transposons, and that this set of genes exhibit high identity with genes found in pathogens and opportunistic pathogens. The set of genes prevalent in P. putida clinical isolates, and absent in environmental isolates, are related with survival under oxidative stress conditions, resistance against biocides, amino acid metabolism and toxin/antitoxin (TA) systems. This set of functions have influence in colonization and survival within human tissues, since they avoid host immune response or enhance stress resistance. An in depth bioinformatic analysis was also carried out to identify genetic clusters that are exclusive to each of the clinical isolates and that correlate with phenotypical differences between them, a secretion system type III-like was found in one of these clinical strains, a determinant of pathogenicity in Gram-negative bacteria.
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Affiliation(s)
- Lázaro Molina
- Environmental Protection Department, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas. C/ Profesor Albareda 1, Granada, Spain
- * E-mail:
| | - Zulema Udaondo
- Environmental Protection Department, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas. C/ Profesor Albareda 1, Granada, Spain
- Abengoa Research, Campus de las Palmas Altas, Sevilla, Spain
| | - Estrella Duque
- Environmental Protection Department, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas. C/ Profesor Albareda 1, Granada, Spain
- Abengoa Research, Campus de las Palmas Altas, Sevilla, Spain
| | - Matilde Fernández
- Environmental Protection Department, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas. C/ Profesor Albareda 1, Granada, Spain
| | - Patricia Bernal
- Environmental Protection Department, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas. C/ Profesor Albareda 1, Granada, Spain
- Imperial College London, South Kensington Campus, London, United Kingdom
| | - Amalia Roca
- Bio-Iliberis R&D, C/ Capileira 7, 18210 Peligros, Granada, Spain
| | - Jesús de la Torre
- Environmental Protection Department, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas. C/ Profesor Albareda 1, Granada, Spain
| | - Juan Luis Ramos
- Environmental Protection Department, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas. C/ Profesor Albareda 1, Granada, Spain
- Abengoa Research, Campus de las Palmas Altas, Sevilla, Spain
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29
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Sarcosine Catabolism in Pseudomonas aeruginosa Is Transcriptionally Regulated by SouR. J Bacteriol 2015; 198:301-10. [PMID: 26503852 DOI: 10.1128/jb.00739-15] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 10/22/2015] [Indexed: 01/18/2023] Open
Abstract
UNLABELLED Sarcosine (N-methylglycine) is present in many environments inhabited by pseudomonads and is likely most often encountered as an intermediate in the metabolism of choline, carnitine, creatine, and glyphosate. While the enzymology of sarcosine metabolism has been relatively well studied in bacteria, the regulatory mechanisms governing catabolism have remained largely unknown. We previously determined that the sarcosine-catabolic (sox) operon of Pseudomonas aeruginosa is induced by the AraC family regulator GbdR in response to glycine betaine and dimethylglycine. However, induction of these genes was still observed in response to sarcosine in a gbdR deletion mutant, indicating that an independent sarcosine-responsive transcription factor also acted at this locus. Our goal in this study was to identify and characterize this regulator. Using a transposon-based genetic screen, we identified PA4184, or SouR (sarcosine oxidation and utilization regulator), as the sarcosine-responsive regulator of the sox operon, with tight induction specificity for sarcosine. The souR gene is required for appreciable growth on sarcosine as a carbon and nitrogen source. We also characterized the transcriptome response to sarcosine governed by SouR using microarray analyses and performed electrophoretic mobility shift assays to identify promoters directly regulated by the transcription factor. Finally, we characterized PA3630, or GfnR (glutathione-dependent formaldehyde neutralization regulator), as the regulator of the glutathione-dependent formaldehyde detoxification system in P. aeruginosa that is expressed in response to formaldehyde released during the catabolism of sarcosine. This study expands our understanding of sarcosine metabolic regulation in bacteria through the identification and characterization of the first known sarcosine-responsive transcriptional regulator. IMPORTANCE The Pseudomonas aeruginosa genome encodes many diverse metabolic pathways, yet the specific transcription regulators controlling their expression remain mostly unknown. Here, we used a genetic screen to identify the sarcosine-specific regulator of the sarcosine oxidase operon, which we have named SouR. SouR is the first bacterial regulator shown to respond to sarcosine, and it is required for growth on sarcosine. Sarcosine is found in its free form and is also an intermediate in the catabolic pathways of glycine betaine, carnitine, creatine, and glyphosate. The similarity of SouR to the regulators of carnitine and glycine betaine catabolism suggests evolutionary diversification within this regulatory family to allow response to structurally similar but physiologically distinct ligands.
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30
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Halavaty AS, Rich RL, Chen C, Joo JC, Minasov G, Dubrovska I, Winsor JR, Myszka DG, Duban M, Shuvalova L, Yakunin AF, Anderson WF. Structural and functional analysis of betaine aldehyde dehydrogenase from Staphylococcus aureus. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2015; 71:1159-75. [PMID: 25945581 PMCID: PMC4427200 DOI: 10.1107/s1399004715004228] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 03/01/2015] [Indexed: 02/02/2023]
Abstract
When exposed to high osmolarity, methicillin-resistant Staphylococcus aureus (MRSA) restores its growth and establishes a new steady state by accumulating the osmoprotectant metabolite betaine. Effective osmoregulation has also been implicated in the acquirement of a profound antibiotic resistance by MRSA. Betaine can be obtained from the bacterial habitat or produced intracellularly from choline via the toxic betaine aldehyde (BA) employing the choline dehydrogenase and betaine aldehyde dehydrogenase (BADH) enzymes. Here, it is shown that the putative betaine aldehyde dehydrogenase SACOL2628 from the early MRSA isolate COL (SaBADH) utilizes betaine aldehyde as the primary substrate and nicotinamide adenine dinucleotide (NAD(+)) as the cofactor. Surface plasmon resonance experiments revealed that the affinity of NAD(+), NADH and BA for SaBADH is affected by temperature, pH and buffer composition. Five crystal structures of the wild type and three structures of the Gly234Ser mutant of SaBADH in the apo and holo forms provide details of the molecular mechanisms of activity and substrate specificity/inhibition of this enzyme.
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Affiliation(s)
- Andrei S. Halavaty
- Department of Biochemistry and Molecular Genetics, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA
- Center for Structural Genomics of Infectious Diseases (CSGID), Chicago, IL 60611, USA
| | | | - Chao Chen
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Jeong Chan Joo
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - George Minasov
- Department of Biochemistry and Molecular Genetics, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA
- Center for Structural Genomics of Infectious Diseases (CSGID), Chicago, IL 60611, USA
| | - Ievgeniia Dubrovska
- Department of Biochemistry and Molecular Genetics, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA
- Center for Structural Genomics of Infectious Diseases (CSGID), Chicago, IL 60611, USA
| | - James R. Winsor
- Department of Biochemistry and Molecular Genetics, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA
- Center for Structural Genomics of Infectious Diseases (CSGID), Chicago, IL 60611, USA
| | | | - Mark Duban
- Center for Structural Genomics of Infectious Diseases (CSGID), Chicago, IL 60611, USA
| | - Ludmilla Shuvalova
- Department of Biochemistry and Molecular Genetics, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA
- Center for Structural Genomics of Infectious Diseases (CSGID), Chicago, IL 60611, USA
| | - Alexander F. Yakunin
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Wayne F. Anderson
- Department of Biochemistry and Molecular Genetics, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA
- Center for Structural Genomics of Infectious Diseases (CSGID), Chicago, IL 60611, USA
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31
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Deciphering the role of multiple betaine-carnitine-choline transporters in the Halophile Vibrio parahaemolyticus. Appl Environ Microbiol 2014; 81:351-63. [PMID: 25344241 DOI: 10.1128/aem.02402-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Vibrio parahaemolyticus is a halophile that is the predominant cause of bacterial seafood-related gastroenteritis worldwide. To survive in the marine environment, V. parahaemolyticus must have adaptive strategies to cope with salinity changes. Six putative compatible solute (CS) transport systems were previously predicted from the genome sequence of V. parahaemolyticus RIMD2210633. In this study, we determined the role of the four putative betaine-carnitine-choline transporter (BCCT) homologues VP1456, VP1723, VP1905, and VPA0356 in the NaCl stress response. Expression analysis of the four BCCTs subjected to NaCl upshock showed that VP1456, VP1905, and VPA0356, but not VP1723, were induced. We constructed in-frame single-deletion mutant strains for all four BCCTs, all of which behaved similarly to the wild-type strain, demonstrating a redundancy of the systems. Growth analysis of a quadruple mutant and four BCCT triple mutants demonstrated the requirement for at least one BCCT for efficient CS uptake. We complemented Escherichia coli MHK13, a CS synthesis- and transporter-negative strain, with each BCCT and examined CS uptake by growth analysis and (1)H nuclear magnetic resonance (NMR) spectroscopy analyses. These data demonstrated that VP1456 had the most diverse substrate transport ability, taking up glycine betaine (GB), proline, choline, and ectoine. VP1456 was the sole ectoine transporter. In addition, the data demonstrated that VP1723 can transport GB, proline, and choline, whereas VP1905 and VPA0356 transported only GB. Overall, the data showed that the BCCTs are functional and that there is redundancy among them.
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Jackson AA, Daniels EF, Hammond JH, Willger SD, Hogan DA. Global regulator Anr represses PlcH phospholipase activity in Pseudomonas aeruginosa when oxygen is limiting. MICROBIOLOGY-SGM 2014; 160:2215-2225. [PMID: 25073853 DOI: 10.1099/mic.0.081158-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Haemolytic phospholipase C (PlcH) is a potent virulence and colonization factor that is expressed at high levels by Pseudomonas aeruginosa within the mammalian host. The phosphorylcholine liberated from phosphatidylcholine and sphingomyelin by PlcH is further catabolized into molecules that both support growth and further induce plcH expression. We have shown previously that the catabolism of PlcH-released choline leads to increased activity of Anr, a global transcriptional regulator that promotes biofilm formation and virulence. Here, we demonstrated the presence of a negative feedback loop in which Anr repressed plcH transcription and we proposed that this regulation allowed for PlcH levels to be maintained in a way that promotes productive host-pathogen interactions. Evidence for Anr-mediated regulation of PlcH came from data showing that growth at low oxygen (1%) repressed PlcH abundance and plcH transcription in the WT, and that plcH transcription was enhanced in an Δanr mutant. The plcH promoter featured an Anr consensus sequence that was conserved across all P. aeruginosa genomes and mutation of conserved nucleotides within the Anr consensus sequence increased plcH expression under hypoxic conditions. The Anr-regulated transcription factor Dnr was not required for this effect. The loss of Anr was not sufficient to completely derepress plcH transcription as GbdR, a positive regulator of plcH, was required for expression. Overexpression of Anr was sufficient to repress plcH transcription even at 21 % oxygen. Anr repressed plcH expression and phospholipase C activity in a cell culture model for P. aeruginosa-epithelial cell interactions.
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Affiliation(s)
- Angelyca A Jackson
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, 208 Vail Building, Hanover, NH 03755, USA
| | - Emily F Daniels
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, 208 Vail Building, Hanover, NH 03755, USA
| | - John H Hammond
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, 208 Vail Building, Hanover, NH 03755, USA
| | - Sven D Willger
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, 208 Vail Building, Hanover, NH 03755, USA
| | - Deborah A Hogan
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, 208 Vail Building, Hanover, NH 03755, USA
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Hampel KJ, LaBauve AE, Meadows JA, Fitzsimmons LF, Nock AM, Wargo MJ. Characterization of the GbdR regulon in Pseudomonas aeruginosa. J Bacteriol 2014; 196:7-15. [PMID: 24097953 PMCID: PMC3911141 DOI: 10.1128/jb.01055-13] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 10/01/2013] [Indexed: 12/15/2022] Open
Abstract
Pseudomonas aeruginosa displays tremendous metabolic diversity, controlled in part by the abundance of transcription regulators in the genome. We have been investigating P. aeruginosa's response to the host, particularly changes regulated by the host-derived quaternary amines choline and glycine betaine (GB). We previously identified GbdR as an AraC family transcription factor that directly regulates choline acquisition from host phospholipids (via binding to plcH and pchP promoters), is required for catabolism of the choline metabolite GB, and is an activator that induces transcription in response to GB or dimethylglycine. Our goal was to characterize the GbdR regulon in P. aeruginosa by using genetics and chemical biology in combination with transcriptomics and in vitro DNA-binding assays. Here we show that GbdR activation regulates transcription of 26 genes from 12 promoters, 11 of which have measureable binding to GbdR in vitro. The GbdR regulon includes the genes encoding GB, dimethylglycine, sarcosine, glycine, and serine catabolic enzymes and the BetX and CbcXWV quaternary amine transport proteins. We characterized the GbdR consensus binding site and used it to identify that the recently characterized acetylcholine esterase gene, choE (PA4921), is also regulated by GbdR. The regulon member not directly controlled by GbdR is the secreted lipase gene lipA, which was also the only regulon member repressed under GbdR-activating conditions. Determination of the GbdR regulon provides deeper understanding of how GbdR links bacterial metabolism and virulence. Additionally, identification of two uncharacterized regulon members suggests roles for these proteins in response to choline metabolites.
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Affiliation(s)
- Ken J. Hampel
- Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, Vermont, USA
| | - Annette E. LaBauve
- Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, Vermont, USA
- The Vermont Lung Center, University of Vermont College of Medicine, Burlington, Vermont, USA
| | - Jamie A. Meadows
- Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, Vermont, USA
| | - Liam F. Fitzsimmons
- Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, Vermont, USA
| | - Adam M. Nock
- Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, Vermont, USA
| | - Matthew J. Wargo
- Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, Vermont, USA
- The Vermont Lung Center, University of Vermont College of Medicine, Burlington, Vermont, USA
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LaBauve AE, Wargo MJ. Detection of host-derived sphingosine by Pseudomonas aeruginosa is important for survival in the murine lung. PLoS Pathog 2014; 10:e1003889. [PMID: 24465209 PMCID: PMC3900636 DOI: 10.1371/journal.ppat.1003889] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 12/02/2013] [Indexed: 01/25/2023] Open
Abstract
Pseudomonas aeruginosa is a common environmental bacterium that is also a significant opportunistic pathogen, particularly of the human lung. We must understand how P. aeruginosa responds to the lung environment in order to identify the regulatory changes that bacteria use to establish and maintain infections. The P. aeruginosa response to pulmonary surfactant was used as a model to identify transcripts likely induced during lung infection. The most highly induced transcript in pulmonary surfactant, PA5325 (sphA), is regulated by an AraC-family transcription factor, PA5324 (SphR). We found that sphA was specifically induced by sphingosine in an SphR-dependent manner, and also via metabolism of sphingomyelin, ceramide, or sphingoshine-1-phosphate to sphingosine. These sphingolipids not only play a structural role in lipid membranes, but some are also intracellular and intercellular signaling molecules important in normal eukaryotic cell functions as well as orchestrating immune responses. The members of the SphR transcriptome were identified by microarray analyses, and DNA binding assays showed specific interaction of these promoters with SphR, which enabled us to determine the consensus SphR binding site. SphR binding to DNA was modified by sphingosine and we used labeled sphingosine to demonstrate direct binding of sphingosine by SphR. Deletion of sphR resulted in reduced bacterial survival during mouse lung infection. In vitro experiments show that deletion of sphR increases sensitivity to the antimicrobial effects of sphingosine which could, in part, explain the in vivo phenotype. This is the first identification of a sphingosine-responsive transcription factor in bacteria. We predict that SphR transcriptional regulation may be important in response to many sites of infection in eukaryotes and the presence of homologous transcription factors in other pathogens suggests that sphingosine detection is not limited to P. aeruginosa.
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Affiliation(s)
- Annette E. LaBauve
- Department of Microbiology and Molecular Genetics and The Vermont Lung Center, University of Vermont College of Medicine, Burlington, Vermont, United States of America
| | - Matthew J. Wargo
- Department of Microbiology and Molecular Genetics and The Vermont Lung Center, University of Vermont College of Medicine, Burlington, Vermont, United States of America
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Liberate and grab it, ingest and digest it: the GbdR regulon of the pathogen Pseudomonas aeruginosa. J Bacteriol 2013; 196:3-6. [PMID: 24163344 DOI: 10.1128/jb.01243-13] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The compatible solute glycine betaine is a powerful osmostress protectant, but many microorganisms can also use it as a nutrient. K. J. Hampel et al. (J. Bacteriol. 196:7-15, 2014) defined a regulon in the notorious pathogen Pseudomonas aeruginosa that comprises modules for the harvest and import of the glycine betaine biosynthetic precursor choline and its subsequent catabolism to pyruvate. The reported data link the GbdR activator with the metabolism of host-derived compounds (e.g., phosphocholine) and virulence traits of P. aeruginosa.
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