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Yoon SH, Liang T, Schneider T, Oyler BL, Chandler CE, Ernst RK, Yen GS, Huang Y, Nilsson E, Goodlett DR. Rapid lipid a structure determination via surface acoustic wave nebulization and hierarchical tandem mass spectrometry algorithm. Rapid Commun Mass Spectrom 2016; 30:2555-2560. [PMID: 27582344 DOI: 10.1002/rcm.7728] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 08/19/2016] [Accepted: 08/28/2016] [Indexed: 06/06/2023]
Abstract
RATIONALE Surface acoustic wave nebulization (SAWN) is an easy to use sample transfer method for rapid mass spectrometric analysis. A new standing wave (SW) SAWN chip, with higher ionization efficiency than our previously reported design, is used for rapid analysis of lipids. METHODS The crude, yet fast, Caroff protocol was used for lipid A extraction from Francisella novicida. SW-SAWN with a Waters Synapt G2S quadrupole time-of-flight (QTOF) mass spectrometer was used to generate lipid A ions. Quadrupole collision-induced dissociation (Q-CID) of lipid A at varying CID energies was used to approximate the ion trap MSn data required for our hierarchical tandem mass spectrometry (HiTMS) algorithm. Structural hypotheses can be obtained directly from the HiTMS algorithm to identify species-specific lipid A molecules. RESULTS SW-SAWN successfully generated ions from lipid A extracted from Francisella novicida using the faster Caroff method. In addition, varying collision energies were used to generate tandem mass spectra similar to MS3 and MS4 spectra from an ion trap. The Q-CID spectra are compatible with our HiTMS algorithm and offer an improvement over lipid A tandem mass spectra acquired in an ion trap. CONCLUSIONS Combining SW-SAWN and Q-CID enabled more structural assignments than previously reported in half the time. The ease of generating spectra by SAWN tandem MS in combination with HiTMS interpretation offers high-throughput lipid A structural analysis and thereby rapid detection of pathogens based on lipid fingerprinting. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Sung Hwan Yoon
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, 650W Baltimore St., Baltimore, MD, 21201, USA
| | - Tao Liang
- Department of Pharmaceutical Science, School of Pharmacy, University of Maryland, 20N Pine St., Baltimore, MD, 21201, USA
| | - Thomas Schneider
- Department of Pharmaceutical Science, School of Pharmacy, University of Maryland, 20N Pine St., Baltimore, MD, 21201, USA
| | - Benjamin L Oyler
- Department of Pharmaceutical Science, School of Pharmacy, University of Maryland, 20N Pine St., Baltimore, MD, 21201, USA
| | - Courtney E Chandler
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, 650W Baltimore St., Baltimore, MD, 21201, USA
| | - Robert K Ernst
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, 650W Baltimore St., Baltimore, MD, 21201, USA
| | - Gloria S Yen
- Deurion LLC, 3518 Fremont Ave #503, Seattle, WA, 98103, USA
| | - Yue Huang
- Deurion LLC, 3518 Fremont Ave #503, Seattle, WA, 98103, USA
| | - Erik Nilsson
- Deurion LLC, 3518 Fremont Ave #503, Seattle, WA, 98103, USA
| | - David R Goodlett
- Department of Pharmaceutical Science, School of Pharmacy, University of Maryland, 20N Pine St., Baltimore, MD, 21201, USA
- Deurion LLC, 3518 Fremont Ave #503, Seattle, WA, 98103, USA
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102
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Li Y, Yoon SH, Wang X, Ernst RK, Goodlett DR. Structural derivation of lipid A from Cronobacter sakazakii using tandem mass spectrometry. Rapid Commun Mass Spectrom 2016; 30:2265-2270. [PMID: 27502448 DOI: 10.1002/rcm.7712] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 07/18/2016] [Accepted: 08/03/2016] [Indexed: 06/06/2023]
Abstract
RATIONALE Cronobacter sakazakii is a Gram-negative opportunistic pathogen that can cause necrotizing enterocolitis, bacteremia, and meningitis. Lipid A, the glycolipid membrane anchor of lipopolysaccharide (LPS), is a potential virulence factor for C. sakazakii. Given the potential importance of this molecule in infection and virulence, structural characterization of lipid A was carried out. METHODS The structural characterization of lipid A extracted from C. sakazakii was performed using electrospray ionization and collision-induced dissociation in a linear ion trap mass spectrometer. Specifically, for detailed structural characterization, hierarchical tandem mass spectrometry was performed on the dominant ions present in the precursor ion mass spectra. By comparing the C. sakazakii fragmentation pathways to those of the known structure of E. coli lipid A, a structure of C. sakazakii lipid A was derived. RESULTS The precursor ion at m/z 1796 from C. sakazakii is produced from a lipid A molecule where the acyl chains between the 2'b (C14) and 3'b (C12) positions are reversed as compared to E. coli lipid A. Additionally, the precursor ion at m/z 1824 from C. sakazakii corresponds to an E. coli structure with the same acyl chain at the 2'b position (C14), but a longer acyl chain (C14) at the 3'b position versus m/z 1796. CONCLUSIONS Two lipid A structures were derived for the C. sakazakii ions at m/z 1796 and 1824. They differed in composition at the 2'b and 3'b acyl chain substituents, which may be a result of differences in substrate specificity of the two lipid A acyl chain transferases: LpxL and LpxM. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Yanyan Li
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.
- Joint International Research Laboratory of Food Safety, Jiangnan University, Wuxi, 214122, China.
| | - Sung Hwan Yoon
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD, 21201, USA
| | - Xiaoyuan Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
- Joint International Research Laboratory of Food Safety, Jiangnan University, Wuxi, 214122, China
| | - Robert K Ernst
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD, 21201, USA
| | - David R Goodlett
- Department of Pharmaceutical Science, School of Pharmacy, University of Maryland, Baltimore, MD, 21201, USA.
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Scott AJ, Flinders B, Cappell J, Liang T, Pelc RS, Tran B, Kilgour DPA, Heeren RMA, Goodlett DR, Ernst RK. Norharmane Matrix Enhances Detection of Endotoxin by MALDI-MS for Simultaneous Profiling of Pathogen, Host, and Vector Systems. Pathog Dis 2016; 74:ftw097. [PMID: 27650574 PMCID: PMC8427938 DOI: 10.1093/femspd/ftw097] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The discovery of novel pathogenic mechanisms engaged during bacterial infections requires
the evolution of advanced techniques. Here, we evaluate the dual polarity matrix
norharmane (NRM) to improve detection of bacterial lipid A (endotoxin), from host and
vector tissues infected withFrancisella novicida (Fn).
We evaluated NRM for improved detection and characterization of a wide range of lipids in
both positive and negative polarities, including lipid A and phospholipids across a range
of matrix-assisted laser desorption-ionization-coupled applications. NRM matrix improved
the limit of detection (LOD) for monophosphoryl lipid A (MPLA) down to picogram level
representing a 10-fold improvement of LOD versus 2,5-dihydroxybenzoic acid and 100-fold
improvement of LOD versus 9-aminoacridine (9-AA). Improved LOD for lipid A subsequently
facilitated detection of theFn lipid A major ion (m/z
1665) from extracts of infected mouse spleen and the
temperature-modifiedFn lipid A atm/z 1637 from
infectedDermacentor variabilis ticks. Finally, we simultaneously mapped
bacterial phospholipid signatures within anFn-infected spleen along with
an exclusively host-derived inositol-based phospholipid (m/z 933)
demonstrating coprofiling of the host-pathogen interaction. Expanded use of NRM matrix in
other infection models and endotoxin-targeting imaging experiments will improve our
understanding of the lipid interactions at the host-pathogen interface.
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Affiliation(s)
- Alison J Scott
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland Baltimore, Baltimore, Maryland, USA
| | - Bryn Flinders
- FOM-Institute AMOLF, Amsterdam, The Netherlands Maastricht Multimodal Molecular Imaging Institute (M4I), Maastricht University, Maastricht, The Netherlands
| | - Joanna Cappell
- FOM-Institute AMOLF, Amsterdam, The Netherlands Maastricht Multimodal Molecular Imaging Institute (M4I), Maastricht University, Maastricht, The Netherlands
| | - Tao Liang
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland Baltimore, Baltimore, Maryland, USA
| | - Rebecca S Pelc
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland Baltimore, Baltimore, Maryland, USA
| | - Bao Tran
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland Baltimore, Baltimore, Maryland, USA
| | - David P A Kilgour
- Nottingham Trent University, Chemistry and Forensics, Clifton Campus, Rosalind Franklin Building, Nottingham, UK
| | - Ron M A Heeren
- FOM-Institute AMOLF, Amsterdam, The Netherlands Maastricht Multimodal Molecular Imaging Institute (M4I), Maastricht University, Maastricht, The Netherlands
| | - David R Goodlett
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland Baltimore, Baltimore, Maryland, USA
| | - Robert K Ernst
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland Baltimore, Baltimore, Maryland, USA
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Kawasaki K, Ernst RK, Miller SI. Purification and characterization of deacylated and/or palmitoylated lipid A species unique to Salmonella enterica serovar Typhimurium. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/09680519050110010101] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The Salmonella enterica serovar Typhimurium virulence gene products PhoP/PhoQ sense host microenvironments to regulate the expression of a lipid A 3- O-deacylase, PagL, and a lipid A palmitoyltransferase, PagP. Therefore, deacylation and/or palmitoylation of lipid A could occur in Salmonellae adapted to host environments. The PhoP/PhoQ-regulated modification of lipid A alters host recognition and signaling, and may play an important role in host defense against Salmonellae infection. Here we report the purification and characterization of modified lipid A species. Deacylated lipid A, deacylated and palmitoylated lipid A, and palmitoylated lipid A species were generated in Escherichia coli cells heterologously expressing salmonellae PagL and/or PagP, and then purified by sequential thin-layer chromatography. The purified lipid A species showed m/z values that correspond to single lipid A species on mass spectrometry analysis. The modified lipid A species showed reduced ability to induce cellular signaling through Toll-like receptor 4, suggesting a specific function of the lipid A modifications in the pathogenesis of salmonellae infection.
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Affiliation(s)
- Kiyoshi Kawasaki
- Department of Microbiology, University of Washington, Seattle, Washington, USA,
| | - Robert K. Ernst
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Samuel I. Miller
- Department of Microbiology, University of Washington, Seattle, Washington, USA, Department of Genome Sciences, University of Washington, Seattle, Washington, USA
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105
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Kawasaki K, Ernst RK, Miller SI. Deacylation and palmitoylation of lipid A by Salmonellae outer membrane enzymes modulate host signaling through Toll-like receptor 4. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/09680519040100061001] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The Salmonella typhimurium virulence gene products, PhoP/PhoQ sense host micro-environments to regulate the expression of a lipid A 3- O-deacylase, PagL, and a lipid A palmitoyltransferase, PagP. Therefore, deacylation and/or palmitoylation of lipid A could occur in Salmonellae adapted to host environments. The acylation state of lipid A can alter host recognition and signaling by Toll-like receptor (TLR) 4, and may play an important role in host defenses against Salmonellae infection. Deacylated lipid A, deacylated and palmitoylated lipid A, palmitoylated lipid A, and unmodified lipid A species were purified, and the activity was examined using cell lines expressing recombinant human or mouse TLR4. Compared with unmodified lipid A, the modified lipid A species are 10—100-fold less active. These results suggest that PagL and PagP modify lipid A to reduce TLR4-signaling as part of Salmonellae adaptation to the host environment.
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Affiliation(s)
- Kiyoshi Kawasaki
- Department of Microbiology, University of Washington, Seattle, Washington, USA
| | - Robert K. Ernst
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Samuel I. Miller
- Department of Microbiology, University of Washington, Seattle, Washington, USA, Department of Genome Sciences, University of Washington, Seattle, Washington, USA,
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Ernst RK, Hajjar AM, Tsai JH, Moskowitz SM, Wilson CB, Miller SI. Pseudomonas aeruginosa lipid A diversity and its recognition by Toll-like receptor 4. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/09680519030090060201] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Lipid A is the pro-inflammatory component of bacterial lipopolysaccharide, the major surface component of Gram-negative bacteria. Gram-negative bacteria alter the structure of lipid A in response to specific environmental conditions including those found upon colonization of a host. The opportunistic pathogen Pseudomonas aeruginosa synthesizes a unique hexa-acylated lipid A containing palmitate and aminoarabinose during adaptation to the cystic fibrosis airway. Different lipid A species are observed in P. aeruginosa isolated from non-cystic fibrosis associated infections. Here we report that P. aeruginosa isolates from the airway of a cystic fibrosis patient with severe pulmonary disease synthesized a novel hepta-acylated lipid A. Cystic fibrosis-specific P. aeruginosa lipid A modifications result in resistance to host antimicrobial peptides and increased recognition by human Toll-like receptor 4 (TLR4). Using P. aeruginosa lipid A with different levels of acylation, we identified a 222 amino acid region in the extracellular portion of human TLR4 that is required for the differential recognition of cystic fibrosis-specific lipid A. P. aeruginosa adaptation to the human airway may, therefore, play a fundamental role in the progressive lung damage associated with cystic fibrosis.
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Affiliation(s)
- Robert K. Ernst
- Department of Medicine, University of Washington, Seattle, Washington, USA,
| | - Adeline M. Hajjar
- Department of Immunology, University of Washington, Seattle, Washington, USA
| | - Jeff H. Tsai
- Department of Immunology, University of Washington, Seattle, Washington, USA
| | - Samuel M. Moskowitz
- Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | - Christopher B. Wilson
- Department of Immunology, University of Washington, Seattle, Washington, USA, Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | - Samuel I. Miller
- Department of Medicine, University of Washington, Seattle, Washington, USA, Department of Genome Sciences, University of Washington, Seattle, Washington, USA, Department of Microbiology, University of Washington, Seattle, Washington, USA
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107
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SenGupta S, Hittle LE, Ernst RK, Uriarte SM, Mitchell TC. A Pseudomonas aeruginosa hepta-acylated lipid A variant associated with cystic fibrosis selectively activates human neutrophils. J Leukoc Biol 2016; 100:1047-1059. [PMID: 27538572 DOI: 10.1189/jlb.4vma0316-101r] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 07/20/2016] [Indexed: 12/12/2022] Open
Abstract
Pseudomonas aeruginosa (PA) infection in cystic fibrosis (CF) lung disease causes airway neutrophilia and hyperinflammation without effective bacterial clearance. We evaluated the immunostimulatory activities of lipid A, the membrane anchor of LPS, isolated from mutants of PA that synthesize structural variants, present in the airways of patients with CF, to determine if they correlate with disease severity and progression. In a subset of patients with a severe late stage of CF disease, a unique hepta-acylated lipid A, hepta-1855, is synthesized. In primary human cell cultures, we found that hepta-1855 functioned as a potent TLR4 agonist by priming neutrophil respiratory burst and stimulating strong IL-8 from monocytes and neutrophils. hepta-1855 also had a potent survival effect on neutrophils. However, it was less efficient in stimulating neutrophil granule exocytosis and also less potent in triggering proinflammatory TNF-α response from monocytes. In PA isolates that do not synthesize hepta-1855, a distinct CF-specific adaptation favors synthesis of a penta-1447 and hexa-1685 LPS mixture. We found that penta-1447 lacked immunostimulatory activity but interfered with inflammatory IL-8 synthesis in response to hexa-1685. Together, these observations suggest a potential contribution of hepta-1855 to maintenance of the inflammatory burden in late-stage CF by recruiting neutrophils via IL-8 and promoting their survival, an effect presumably amplified by the absence of penta-1447. Moreover, the relative inefficiency of hepta-1855 in triggering neutrophil degranulation may partly explain the persistence of PA in CF disease, despite extensive airway neutrophilia.
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Affiliation(s)
- Shuvasree SenGupta
- Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, Kentucky, USA
| | - Lauren E Hittle
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, Maryland, USA
| | - Robert K Ernst
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, Maryland, USA
| | - Silvia M Uriarte
- Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, Kentucky, USA; .,Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky, USA; and
| | - Thomas C Mitchell
- Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, Kentucky, USA;
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Maldarelli GA, Piepenbrink KH, Scott AJ, Freiberg JA, Song Y, Achermann Y, Ernst RK, Shirtliff ME, Sundberg EJ, Donnenberg MS, von Rosenvinge EC. Type IV pili promote early biofilm formation by Clostridium difficile. Pathog Dis 2016; 74:ftw061. [PMID: 27369898 DOI: 10.1093/femspd/ftw061] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2016] [Indexed: 12/20/2022] Open
Abstract
Increasing morbidity and mortality from Clostridium difficile infection (CDI) present an enormous challenge to healthcare systems. Clostridium difficile express type IV pili (T4P), but their function remains unclear. Many chronic and recurrent bacterial infections result from biofilms, surface-associated bacterial communities embedded in an extracellular matrix. CDI may be biofilm mediated; T4P are important for biofilm formation in a number of organisms. We evaluate the role of T4P in C. difficile biofilm formation using RNA sequencing, mutagenesis and complementation of the gene encoding the major pilin pilA1, and microscopy. RNA sequencing demonstrates that, in comparison to other growth phenotypes, C. difficile growing in a biofilm has a distinct RNA expression profile, with significant differences in T4P gene expression. Microscopy of T4P-expressing and T4P-deficient strains suggests that T4P play an important role in early biofilm formation. A non-piliated pilA1 mutant forms an initial biofilm of significantly reduced mass and thickness in comparison to the wild type. Complementation of the pilA1 mutant strain leads to formation of a biofilm which resembles the wild-type biofilm. These findings suggest that T4P play an important role in early biofilm formation. Novel strategies for confronting biofilm infections are emerging; our data suggest that similar strategies should be investigated in CDI.
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Affiliation(s)
- Grace A Maldarelli
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Kurt H Piepenbrink
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Alison J Scott
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Jeffrey A Freiberg
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Yang Song
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Yvonne Achermann
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Robert K Ernst
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Mark E Shirtliff
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Eric J Sundberg
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD 21201, USA Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Michael S Donnenberg
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Erik C von Rosenvinge
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA Department of Veterans Affairs, VA Maryland Health Care System, Baltimore, MD 21201, USA
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109
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SenGupta S, Uriarte SM, Ernst RK, Mitchell TC. Possible link between cystic fibrosis specific lipid A adaptations by Pseudomonas aeruginosa and disease associated hyperinflammation. The Journal of Immunology 2016. [DOI: 10.4049/jimmunol.196.supp.65.23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
Pseudomonas aeruginosa infection in cystic fibrosis (CF) lung disease causes airway neutrophilia and hyperinflammation without being cleared effectively. We evaluated the immunostimulatory activities of lipid A variants synthesized by P. aeruginosa (PA) exclusively in CF patients to determine if they correlate with CF disease severity and progression. One third of the PA isolates from CF patients with late severe stage express a unique hepta–acylated lipid A; hepta-1855 (m/z=1855) isoform. In primary cell cultures, we found that hepta-1855 functioned as a potent TLR4 agonist by priming neutrophil respiratory burst and stimulating strong chemokine response (interleukin-8 or IL-8) from monocytes and neutrophils. Hepta-1855 also had a potent survival effect on neutrophils. However, it was less efficient in inducing neutrophil granule exocytosis and was also less potent in triggering pro-inflammatory TNF-α response from monocytes. A precursor hexa-1616, found in hepta-1855 containing LPS mixtures, did not have direct inflammatory activity on neutrophils but induced moderate IL-8 response. Together, our data suggest a potential contribution of hepta-1855 to late CF stage associated excessive inflammatory burden by recruiting neutrophils via IL-8 and promoting their maintenance through its survival effect. Being a chemoattractant stimulus, hexa-1616, may serve as an accomplice to hepta-1855. Moreover, the relative inefficiency of hepta-1855 in triggering degranulation may partly explain the persistence of PA in CF disease in spite of neutrophil dominated inflammation.
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110
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Varga JJ, Barbier M, Mulet X, Bielecki P, Bartell JA, Owings JP, Martinez-Ramos I, Hittle LE, Davis MR, Damron FH, Liechti GW, Puchałka J, dos Santos VAPM, Ernst RK, Papin JA, Albertí S, Oliver A, Goldberg JB. Genotypic and phenotypic analyses of a Pseudomonas aeruginosa chronic bronchiectasis isolate reveal differences from cystic fibrosis and laboratory strains. BMC Genomics 2015; 16:883. [PMID: 26519161 PMCID: PMC4628258 DOI: 10.1186/s12864-015-2069-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 10/03/2015] [Indexed: 01/24/2023] Open
Abstract
Background Pseudomonas aeruginosa is an environmentally ubiquitous Gram-negative bacterium and important opportunistic human pathogen, causing severe chronic respiratory infections in patients with underlying conditions such as cystic fibrosis (CF) or bronchiectasis. In order to identify mechanisms responsible for adaptation during bronchiectasis infections, a bronchiectasis isolate, PAHM4, was phenotypically and genotypically characterized. Results This strain displays phenotypes that have been associated with chronic respiratory infections in CF including alginate over-production, rough lipopolysaccharide, quorum-sensing deficiency, loss of motility, decreased protease secretion, and hypermutation. Hypermutation is a key adaptation of this bacterium during the course of chronic respiratory infections and analysis indicates that PAHM4 encodes a mutated mutS gene responsible for a ~1,000-fold increase in mutation rate compared to wild-type laboratory strain P. aeruginosa PAO1. Antibiotic resistance profiles and sequence data indicate that this strain acquired numerous mutations associated with increased resistance levels to β-lactams, aminoglycosides, and fluoroquinolones when compared to PAO1. Sequencing of PAHM4 revealed a 6.38 Mbp genome, 5.9 % of which were unrecognized in previously reported P. aeruginosa genome sequences. Transcriptome analysis suggests a general down-regulation of virulence factors, while metabolism of amino acids and lipids is up-regulated when compared to PAO1 and metabolic modeling identified further potential differences between PAO1 and PAHM4. Conclusions This work provides insights into the potential differential adaptation of this bacterium to the lung of patients with bronchiectasis compared to other clinical settings such as cystic fibrosis, findings that should aid the development of disease-appropriate treatment strategies for P. aeruginosa infections. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-2069-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- John J Varga
- Department of Pediatrics, Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis and Sleep, Children's Healthcare of Atlanta, Atlanta, GA, USA. .,Emory + Children's Center for Cystic Fibrosis Research, Emory University and Children's Healthcare of Atlanta, Atlanta, GA, USA. .,Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA.
| | - Mariette Barbier
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA. .,Department of Microbiology, Immunology and Cell Biology, West Virginia University School of Medicine, Morgantown, WV, USA.
| | - Xavier Mulet
- Servicio de Microbiología and Unidad de Investigación, Hospital Son Espases, Instituto de Investigación Sanitaria de Palma (IdISPa), Palma, de Mallorca, Spain.
| | - Piotr Bielecki
- Synthetic and Systems Biology Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany. .,Present address: Immunobiology Department, Yale University, School of Medicine, New Haven, CT, 06511, USA.
| | - Jennifer A Bartell
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA.
| | - Joshua P Owings
- Department of Pediatrics, Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis and Sleep, Children's Healthcare of Atlanta, Atlanta, GA, USA. .,Emory + Children's Center for Cystic Fibrosis Research, Emory University and Children's Healthcare of Atlanta, Atlanta, GA, USA. .,Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA.
| | | | - Lauren E Hittle
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, University of Maryland, Baltimore, MD, USA.
| | - Michael R Davis
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA.
| | - F Heath Damron
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA. .,Department of Microbiology, Immunology and Cell Biology, West Virginia University School of Medicine, Morgantown, WV, USA.
| | - George W Liechti
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA.
| | - Jacek Puchałka
- Servicio de Microbiología and Unidad de Investigación, Hospital Son Espases, Instituto de Investigación Sanitaria de Palma (IdISPa), Palma, de Mallorca, Spain. .,Present address: Dr. von Hauner Children's Hospital, Ludwig Maximilians University, Munich, Germany.
| | - Vitor A P Martins dos Santos
- Systems and Synthetic Biology, Wageningen University, Wageningen, Netherlands. .,Present address: Chair of Systems and Synthetic Biology, Wageningen University, Wageningen, The Netherlands. .,Present address: LifeGlimmer GmbH, Berlin, Germany.
| | - Robert K Ernst
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, University of Maryland, Baltimore, MD, USA.
| | - Jason A Papin
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA.
| | - Sebastian Albertí
- IUNICS, University of the Balearic Islands, Palma, de Mallorca, Spain.
| | - Antonio Oliver
- Servicio de Microbiología and Unidad de Investigación, Hospital Son Espases, Instituto de Investigación Sanitaria de Palma (IdISPa), Palma, de Mallorca, Spain.
| | - Joanna B Goldberg
- Department of Pediatrics, Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis and Sleep, Children's Healthcare of Atlanta, Atlanta, GA, USA. .,Emory + Children's Center for Cystic Fibrosis Research, Emory University and Children's Healthcare of Atlanta, Atlanta, GA, USA. .,Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA.
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Stephens MD, Hubble VB, Ernst RK, van Hoek ML, Melander RJ, Cavanagh J, Melander C. Potentiation of Francisella Resistance to Conventional Antibiotics through Small Molecule Adjuvants. Medchemcomm 2015; 7:128-131. [PMID: 26877862 DOI: 10.1039/c5md00353a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A screen of 20 compounds identified small molecule adjuvants capable of potentiating anitbiotic activty against Francisella philomiragia. Analogue synthesis of an initial hit compound led to the discovery of a potentially new class of small molecule adjuvants containg an indole core. The lead compound was able to lower the MIC of colistin by 32-fold against intrinsically resistant F. philomiragia.
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Affiliation(s)
- Matthew D Stephens
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Veroncia B Hubble
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Robert K Ernst
- Department of Microbial Pathogenesis, University of Maryland - Baltimore, Baltimore, MD 21201, United States
| | - Monique L van Hoek
- School of Systems Biology & National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, VA 20110, United States
| | - Roberta J Melander
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - John Cavanagh
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Christian Melander
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
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Hittle LE, Powell DA, Jones JW, Tofigh M, Goodlett DR, Moskowitz SM, Ernst RK. Site-specific activity of the acyltransferases HtrB1 and HtrB2 in Pseudomonas aeruginosa lipid A biosynthesis. Pathog Dis 2015. [PMID: 26223882 DOI: 10.1093/femspd/ftv053] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Pseudomonas aeruginosa (PA) is an opportunistic Gram-negative pathogen associated with nosocomial infections, acute infections and chronic lung infections in patients with cystic fibrosis. The ability of PA to cause infection can be attributed to its ability to adapt to a multitude of environments. Modification of the lipid A portion of lipopolysaccharide (LPS) is a vital mechanism Gram-negative pathogens use to remodel the outer membrane in response to environmental stimuli. Lipid A, the endotoxic moiety of LPS, is the major component of the outer leaflet of the outer membrane of Gram-negative bacteria making it a critical factor for bacterial adaptation. One way PA modifies its lipid A is through the addition of laurate and 2-hydroxylaurate. This secondary or late acylation is carried out by the acyltransferase, HtrB (LpxL). Analysis of the PA genome revealed the presence of two htrB homologs, PA0011 (htrB1) and PA3242 (htrB2). In this study, we were able to show that each gene identified is responsible for site-specific modification of lipid A. Additionally, deletions of either gene altered resistance to specific classes of antibiotics, cationic antimicrobial peptides and increased membrane permeability suggesting a role for these enzymes in maintaining optimal membrane organization and integrity.
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Affiliation(s)
- Lauren E Hittle
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Daniel A Powell
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Jace W Jones
- Department of Medicinal Chemistry, School of Pharmacy, University of Washington, Seattle, WA 98195, USA
| | - Majid Tofigh
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - David R Goodlett
- Department of Medicinal Chemistry, School of Pharmacy, University of Washington, Seattle, WA 98195, USA
| | - Samuel M Moskowitz
- Department of Medicinal Chemistry, School of Pharmacy, University of Washington, Seattle, WA 98195, USA Department of Pediatrics, Massachusetts General Hospital, Boston, MA 20114, USA
| | - Robert K Ernst
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
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113
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Knodler LA, Crowley SM, Sham HP, Yang H, Wrande M, Ma C, Ernst RK, Steele-Mortimer O, Celli J, Vallance BA. Noncanonical inflammasome activation of caspase-4/caspase-11 mediates epithelial defenses against enteric bacterial pathogens. Cell Host Microbe 2015; 16:249-256. [PMID: 25121752 DOI: 10.1016/j.chom.2014.07.002] [Citation(s) in RCA: 328] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 06/04/2014] [Accepted: 07/01/2014] [Indexed: 12/20/2022]
Abstract
Inflammasome-mediated host defenses have been extensively studied in innate immune cells. Whether inflammasomes function for innate defense in intestinal epithelial cells, which represent the first line of defense against enteric pathogens, remains unknown. We observed enhanced Salmonella enterica serovar Typhimurium colonization in the intestinal epithelium of caspase-11-deficient mice, but not at systemic sites. In polarized epithelial monolayers, siRNA-mediated depletion of caspase-4, a human ortholog of caspase-11, also led to increased bacterial colonization. Decreased rates of pyroptotic cell death, a host defense mechanism that extrudes S. Typhimurium-infected cells from the polarized epithelium, accounted for increased pathogen burdens. The caspase-4 inflammasome also governs activation of the proinflammatory cytokine, interleukin (IL)-18, in response to intracellular (S. Typhimurium) and extracellular (enteropathogenic Escherichia coli) enteric pathogens, via intracellular LPS sensing. Therefore, an epithelial cell-intrinsic noncanonical inflammasome plays a critical role in antimicrobial defense at the intestinal mucosal surface.
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Affiliation(s)
- Leigh A Knodler
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-7090, USA; Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT 59840, USA.
| | - Shauna M Crowley
- Division of Gastroenterology, Department of Pediatrics, Child and Family Research Institute, University of British Columbia, Vancouver BC V6H 3V4, Canada
| | - Ho Pan Sham
- Division of Gastroenterology, Department of Pediatrics, Child and Family Research Institute, University of British Columbia, Vancouver BC V6H 3V4, Canada
| | - Hyungjun Yang
- Division of Gastroenterology, Department of Pediatrics, Child and Family Research Institute, University of British Columbia, Vancouver BC V6H 3V4, Canada
| | - Marie Wrande
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-7090, USA
| | - Caixia Ma
- Division of Gastroenterology, Department of Pediatrics, Child and Family Research Institute, University of British Columbia, Vancouver BC V6H 3V4, Canada
| | - Robert K Ernst
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD 21201, USA
| | - Olivia Steele-Mortimer
- Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT 59840, USA
| | - Jean Celli
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-7090, USA; Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT 59840, USA
| | - Bruce A Vallance
- Division of Gastroenterology, Department of Pediatrics, Child and Family Research Institute, University of British Columbia, Vancouver BC V6H 3V4, Canada.
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Qureshi ZA, Hittle LE, O'Hara JA, Rivera JI, Syed A, Shields RK, Pasculle AW, Ernst RK, Doi Y. Colistin-resistant Acinetobacter baumannii: beyond carbapenem resistance. Clin Infect Dis 2015; 60:1295-303. [PMID: 25632010 DOI: 10.1093/cid/civ048] [Citation(s) in RCA: 258] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 11/07/2014] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND With an increase in the use of colistin methansulfonate (CMS) to treat carbapenem-resistant Acinetobacter baumannii infections, colistin resistance is emerging. METHODS Patients with infection or colonization due to colistin-resistant A. baumannii were identified at a hospital system in Pennsylvania. Clinical data were collected from electronic medical records. Susceptibility testing, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing (MLST) were performed. To investigate the mechanism of colistin resistance, lipid A was subjected to matrix-assisted laser desorption/ionization mass spectrometry. RESULTS Twenty patients with colistin-resistant A. baumannii were identified. Ventilator-associated pneumonia was the most common type of infection. Nineteen patients had received intravenous and/or inhaled CMS for treatment of carbapenem-resistant, colistin-susceptible A. baumannii infection prior to identification of colistin-resistant isolates. The 30-day all-cause mortality rate was 30%. The treatment regimen for colistin-resistant A. baumannii infection associated with the lowest mortality rate was a combination of CMS, a carbapenem, and ampicillin-sulbactam. The colistin-susceptible and -resistant isolates from the same patients were highly related by PFGE, but isolates from different patients were not, suggesting evolution of resistance during CMS therapy. By MLST, all isolates belonged to the international clone II, the lineage that is epidemic worldwide. Phosphoethanolamine modification of lipid A was present in all colistin-resistant A. baumannii isolates. CONCLUSIONS Colistin-resistant A. baumannii occurred almost exclusively among patients who had received CMS for treatment of carbapenem-resistant, colistin-susceptible A. baumannii infection. Lipid A modification by the addition of phosphoethanolamine accounted for colistin resistance. Susceptibility testing for colistin should be considered for A. baumannii identified from CMS-experienced patients.
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Affiliation(s)
- Zubair A Qureshi
- Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pennsylvania
| | - Lauren E Hittle
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore
| | - Jessica A O'Hara
- Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pennsylvania
| | - Jesabel I Rivera
- Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pennsylvania
| | - Alveena Syed
- Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pennsylvania
| | - Ryan K Shields
- Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pennsylvania
| | - Anthony W Pasculle
- Clinical Microbiology Laboratory, University of Pittsburgh Medical Center, Pennsylvania
| | - Robert K Ernst
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore
| | - Yohei Doi
- Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pennsylvania
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115
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Chirakul S, Bartpho T, Wongsurawat T, Taweechaisupapong S, Karoonutaisiri N, Talaat AM, Wongratanacheewin S, Ernst RK, Sermswan RW. Characterization of BPSS1521 (bprD), a regulator of Burkholderia pseudomallei virulence gene expression in the mouse model. PLoS One 2014; 9:e104313. [PMID: 25111708 PMCID: PMC4128674 DOI: 10.1371/journal.pone.0104313] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 07/07/2014] [Indexed: 11/19/2022] Open
Abstract
The Gram-negative saprophytic bacterium Burkholderia pseudomallei is the causative agent of melioidosis, a severe infectious disease of both humans and animals. Severity of the disease is thought to be dependent on both the health status of the host, including diabetes mellitus and kidney disease, and bacterial-derived factors. To identify the bacterial factors important during an acute infection, gene expression profiles in the spleen, lung, and liver of BALB/c (Th2 prototype) and C57BL/6 mice (Th1 prototype) were determined using DNA microarrays. This analysis identified BPSS1521 (bprD), a predicted transcriptional regulator located in the type III secretion system (T3SS-3) operon, to be up regulated, specifically in C57BL/6 mice. BALB/c mice infected with a bprD mutant showed a shorter time to death and increased inflammation, as determined by histopathological analysis and enumeration of bacteria in the spleen. Elevated numbers of multinucleated giant cells (MNGCs), which is the hallmark of melioidosis, were detected in both the wild-type and the bprD mutants; a similar elevation occurs in melioidosis patients. One striking observation was the increased expression of BPSS1520 (bprC), located downstream of bprD, in the bprD mutant. BprC is a regulator of T6SS-1 that is required for the virulence of B. pseudomallei in murine infection models. Deletion of bprD led to the overexpression of bprC and a decreased time to death. bprD expression was elevated in C57BL/6--as compared to BALB/c--mice, suggesting a role for BprD in the natural resistance of C57BL/6 mice to B. pseudomallei. Ultimately, this analysis using mice with different immune backgrounds may enhance our understanding of the outcomes of infection in a variety of models.
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Affiliation(s)
- Sunisa Chirakul
- Melioidosis Research Center, Khon Kaen University, Khon Kaen, Thailand
- Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | | | - Thidathip Wongsurawat
- National Center for Genetic Engineering and Biotechnology (BIOTEC), Pathumthani, Thailand
| | | | - Nitsara Karoonutaisiri
- National Center for Genetic Engineering and Biotechnology (BIOTEC), Pathumthani, Thailand
| | - Adel M. Talaat
- Department of Pathobiology, SVM, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Surasakdi Wongratanacheewin
- Melioidosis Research Center, Khon Kaen University, Khon Kaen, Thailand
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland-Baltimore, Baltimore, Maryland, United States of America
| | - Rasana W. Sermswan
- Melioidosis Research Center, Khon Kaen University, Khon Kaen, Thailand
- Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
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Harris TL, Worthington RJ, Hittle LE, Zurawski DV, Ernst RK, Melander C. Small molecule downregulation of PmrAB reverses lipid A modification and breaks colistin resistance. ACS Chem Biol 2014; 9:122-7. [PMID: 24131198 DOI: 10.1021/cb400490k] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Infections caused by multi-drug resistant bacteria, particularly Gram-negative bacteria, are an ever-increasing problem. While the development of new antibiotics remains one option in the fight against bacteria that have become resistant to currently available antibiotics, an attractive alternative is the development of adjuvant therapeutics that restore the efficacy of existing antibiotics. We report a small molecule adjuvant that suppresses colistin resistance in multidrug resistant Acinetobacter baumannii and Klebsiella pneumoniae by interfering with the expression of a two-component system. The compound downregulates the pmrCAB operon and reverses phosphoethanolamine modification of lipid A responsible for colistin resistance. Furthermore, colistin-susceptible and colistin-resistant bacteria do not evolve resistance to combination treatment. This represents the first definitive example of a compound that breaks antibiotic resistance by directly modulating two-component system activity.
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Affiliation(s)
- Tyler L. Harris
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Roberta J. Worthington
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Lauren E. Hittle
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Baltimore, Maryland 21201, United States
| | - Daniel V. Zurawski
- Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Baltimore, Maryland 21201, United States
| | - Christian Melander
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
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117
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Scott AJ, Jones JW, Orschell CM, MacVittie TJ, Kane MA, Ernst RK. Mass spectrometry imaging enriches biomarker discovery approaches with candidate mapping. Health Phys 2014; 106:120-8. [PMID: 24276555 PMCID: PMC4015108 DOI: 10.1097/hp.0b013e3182a4ec2f] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Integral to the characterization of radiation-induced tissue damage is the identification of unique biomarkers. Biomarker discovery is a challenging and complex endeavor requiring both sophisticated experimental design and accessible technology. The resources within the National Institute of Allergy and Infectious Diseases (NIAID)-sponsored Consortium, Medical Countermeasures Against Radiological Threats (MCART), allow for leveraging robust animal models with novel molecular imaging techniques. One such imaging technique, MALDI (matrix-assisted laser desorption ionization) mass spectrometry imaging (MSI), allows for the direct spatial visualization of lipids, proteins, small molecules, and drugs/drug metabolites-or biomarkers-in an unbiased manner. MALDI-MSI acquires mass spectra directly from an intact tissue slice in discrete locations across an x, y grid that are then rendered into a spatial distribution map composed of ion mass and intensity. The unique mass signals can be plotted to generate a spatial map of biomarkers that reflects pathology and molecular events. The crucial unanswered questions that can be addressed with MALDI-MSI include identification of biomarkers for radiation damage that reflect the response to radiation dose over time and the efficacy of therapeutic interventions. Techniques in MALDI-MSI also enable integration of biomarker identification among diverse animal models. Analysis of early, sublethally irradiated tissue injury samples from diverse mouse tissues (lung and ileum) shows membrane phospholipid signatures correlated with histological features of these unique tissues. This paper will discuss the application of MALDI-MSI for use in a larger biomarker discovery pipeline.
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Affiliation(s)
| | - Jace W. Jones
- University of Maryland, School of Pharmacy, Baltimore, MD
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Jones JW, Scott AJ, Tudor G, Xu PT, Jackson IL, Vujaskovic Z, Booth C, MacVittie TJ, Ernst RK, Kane MA. Identification and quantitation of biomarkers for radiation-induced injury via mass spectrometry. Health Phys 2014; 106:106-19. [PMID: 24276554 PMCID: PMC3843144 DOI: 10.1097/hp.0b013e3182a4ed3b] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Biomarker identification and validation for radiation exposure is a rapidly expanding field encompassing the need for well defined animal models and advanced analytical techniques. The resources within the consortium, Medical Countermeasures Against Radiological Threats (MCART), provide a unique opportunity for accessing well defined animal models that simulate the key sequelae of the acute radiation syndrome and the delayed effects of acute radiation exposure. Likewise, the use of mass spectrometry-based analytical techniques for biomarker discovery and validation enables a robust analytical platform that is amenable to a variety of sample matrices and considered the benchmark for biomolecular identification and quantitation. Herein, the authors demonstrate the use of two targeted mass spectrometry approaches to link established MCART animal models to identified metabolite biomarkers. Circulating citrulline concentration was correlated to gross histological gastrointestinal tissue damage, and retinoic acid production in lung tissue was established to be reduced at early and late time points post high dose irradiation. Going forward, the use of mass spectrometry-based metabolomics coupled to well defined animal models provides the unique opportunity for comprehensive biomarker discovery.
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Affiliation(s)
- Jace W. Jones
- University of Maryland, School of Pharmacy, Department of Pharmaceutical Sciences, Baltimore, MD
| | - Alison J. Scott
- University of Maryland, School of Dentistry, Department of Microbial Pathogenesis, Baltimore, MD
| | | | - Pu-Ting Xu
- University of Maryland, School of Medicine, Department of Radiation Oncology, Baltimore, MD
| | - Isabel L. Jackson
- University of Maryland, School of Medicine, Department of Radiation Oncology, Baltimore, MD
| | - Zeljko Vujaskovic
- University of Maryland, School of Medicine, Department of Radiation Oncology, Baltimore, MD
| | | | - Thomas J. MacVittie
- University of Maryland, School of Medicine, Department of Radiation Oncology, Baltimore, MD
| | - Robert K. Ernst
- University of Maryland, School of Dentistry, Department of Microbial Pathogenesis, Baltimore, MD
| | - Maureen A. Kane
- University of Maryland, School of Pharmacy, Department of Pharmaceutical Sciences, Baltimore, MD
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Thaipisuttikul I, Hittle LE, Chandra R, Zangari D, Dixon CL, Garrett TA, Rasko DA, Dasgupta N, Moskowitz SM, Malmström L, Goodlett DR, Miller SI, Bishop RE, Ernst RK. A divergent Pseudomonas aeruginosa palmitoyltransferase essential for cystic fibrosis-specific lipid A. Mol Microbiol 2013; 91:158-74. [PMID: 24283944 DOI: 10.1111/mmi.12451] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2013] [Indexed: 12/25/2022]
Abstract
Strains of Pseudomonas aeruginosa (PA) isolated from the airways of cystic fibrosis patients constitutively add palmitate to lipid A, the membrane anchor of lipopolysaccharide. The PhoPQ regulated enzyme PagP is responsible for the transfer of palmitate from outer membrane phospholipids to lipid A. This enzyme had previously been identified in many pathogenic Gram-negative bacteria, but in PA had remained elusive, despite abundant evidence that its lipid A contains palmitate. Using a combined genetic and biochemical approach, we identified PA1343 as the PA gene encoding PagP. Although PA1343 lacks obvious primary structural similarity with known PagP enzymes, the β-barrel tertiary structure with an interior hydrocarbon ruler appears to be conserved. PA PagP transfers palmitate to the 3' position of lipid A, in contrast to the 2 position seen with the enterobacterial PagP. Palmitoylated PA lipid A alters host innate immune responses, including increased resistance to some antimicrobial peptides and an elevated pro-inflammatory response, consistent with the synthesis of a hexa-acylated structure preferentially recognized by the TLR4/MD2 complex. Palmitoylation commonly confers resistance to cationic antimicrobial peptides, however, increased cytokine production resulting in inflammation is not seen with other palmitoylated lipid A, indicating a unique role for this modification in PA pathogenesis.
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Affiliation(s)
- Iyarit Thaipisuttikul
- Department of Microbial Pathogenesis, University of Maryland, School of Dentistry, University of Maryland, Baltimore, MD, 21201, USA; Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, 2 Prannok Road, Bangkoknoi, Bangkok, 10700, Thailand
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Chantratita N, Tandhavanant S, Myers ND, Seal S, Arayawichanont A, Kliangsa-ad A, Hittle LE, Ernst RK, Emond MJ, Wurfel MM, Day NPJ, Peacock SJ, West TE. Survey of innate immune responses to Burkholderia pseudomallei in human blood identifies a central role for lipopolysaccharide. PLoS One 2013; 8:e81617. [PMID: 24303060 PMCID: PMC3841221 DOI: 10.1371/journal.pone.0081617] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 10/25/2013] [Indexed: 12/28/2022] Open
Abstract
B. pseudomallei is a gram-negative bacterium that causes the tropical infection melioidosis. In northeast Thailand, mortality from melioidosis approaches 40%. As exemplified by the lipopolysaccharide-Toll-like receptor 4 interaction, innate immune responses to invading bacteria are precipitated by activation of host pathogen recognition receptors by pathogen associated molecular patterns. Human melioidosis is characterized by up-regulation of pathogen recognition receptors and pro-inflammatory cytokine release. In contrast to many gram-negative pathogens, however, the lipopolysaccharide of B. pseudomallei is considered only weakly inflammatory. We conducted a study in 300 healthy Thai subjects to investigate the ex vivo human blood response to various bacterial pathogen associated molecular patterns, including lipopolysaccharide from several bacteria, and to two heat-killed B. pseudomallei isolates. We measured cytokine levels after stimulation of fresh whole blood with a panel of stimuli. We found that age, sex, and white blood cell count modulate the innate immune response to B. pseudomallei. We further observed that, in comparison to other stimuli, the innate immune response to B. pseudomallei is most highly correlated with the response to lipopolysaccharide. The magnitude of cytokine responses induced by B. pseudomallei lipopolysaccharide was significantly greater than those induced by lipopolysaccharide from Escherichia coli and comparable to many responses induced by lipopolysaccharide from Salmonella minnesota despite lower amounts of lipid A in the B. pseudomallei lipopolysaccharide preparation. In human monocytes stimulated with B. pseudomallei, addition of polymyxin B or a TLR4/MD-2 neutralizing antibody inhibited the majority of TNF-α production. Challenging existing views, our data indicate that the innate immune response to B. pseudomallei in human blood is largely driven by lipopolysaccharide, and that the response to B. pseudomallei lipopolysaccharide in blood is greater than the response to other lipopolysaccharide expressing isolates. Our findings suggest that B. pseudomallei lipopolysaccharide may play a central role in stimulating the host response in melioidosis.
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Affiliation(s)
- Narisara Chantratita
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- * E-mail:
| | - Sarunporn Tandhavanant
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Nicolle D. Myers
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Sudeshna Seal
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Washington, Seattle, Washington, United States of America
| | | | - Aroonsri Kliangsa-ad
- Department of Clinical Pathology, Sappasithiprasong Hospital, Ubon Ratchathani, Thailand
| | - Lauren E. Hittle
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Maryland, United States of America
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Maryland, United States of America
| | - Mary J. Emond
- Department of Biostatistics, University of Washington, Seattle, WA, United States of America
| | - Mark M. Wurfel
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Nicholas P. J. Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Center for Clinical Vaccinology and Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | - Sharon J. Peacock
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Cambridge, United Kingdom
| | - T. Eoin West
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Washington, Seattle, Washington, United States of America
- International Respiratory and Severe Illness Center, University of Washington, Seattle, Washington, United States of America
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Hagar JA, Powell DA, Aachoui Y, Ernst RK, Miao EA. Cytoplasmic LPS activates caspase-11: implications in TLR4-independent endotoxic shock. Science 2013; 341:1250-3. [PMID: 24031018 DOI: 10.1126/science.1240988] [Citation(s) in RCA: 896] [Impact Index Per Article: 81.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Inflammatory caspases, such as caspase-1 and -11, mediate innate immune detection of pathogens. Caspase-11 induces pyroptosis, a form of programmed cell death, and specifically defends against bacterial pathogens that invade the cytosol. During endotoxemia, however, excessive caspase-11 activation causes shock. We report that contamination of the cytoplasm by lipopolysaccharide (LPS) is the signal that triggers caspase-11 activation in mice. Specifically, caspase-11 responds to penta- and hexa-acylated lipid A, whereas tetra-acylated lipid A is not detected, providing a mechanism of evasion for cytosol-invasive Francisella. Priming the caspase-11 pathway in vivo resulted in extreme sensitivity to subsequent LPS challenge in both wild-type and Tlr4-deficient mice, whereas Casp11-deficient mice were relatively resistant. Together, our data reveal a new pathway for detecting cytoplasmic LPS.
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Affiliation(s)
- Jon A Hagar
- Department of Microbiology and Immunology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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122
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Li Y, Wang Z, Chen J, Ernst RK, Wang X. Influence of lipid A acylation pattern on membrane permeability and innate immune stimulation. Mar Drugs 2013; 11:3197-208. [PMID: 24065161 PMCID: PMC3806461 DOI: 10.3390/md11093197] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Revised: 07/29/2013] [Accepted: 08/09/2013] [Indexed: 12/13/2022] Open
Abstract
Lipid A, the hydrophobic anchor of lipopolysaccharide (LPS), is an essential component in the outer membrane of Gram-negative bacteria. It can stimulate the innate immune system via Toll-like receptor 4/myeloid differentiation factor 2 (TLR4/MD2), leading to the release of inflammatory cytokines. In this study, six Escherichia coli strains which can produce lipid A with different acylation patterns were constructed; the influence of lipid A acylation pattern on the membrane permeability and innate immune stimulation has been systematically investigated. The lipid A species were isolated and identified by matrix assisted laser ionization desorption-time of flight/tandem mass spectrometry. N-Phenyl naphthylamine uptake assay and antibiotic susceptibility test showed that membrane permeability of these strains were different. The lower the number of acyl chains in lipid A, the stronger the membrane permeability. LPS purified from these strains were used to stimulate human or mouse macrophage cells, and different levels of cytokines were induced. Compared with wild type hexa-acylated LPS, penta-acylated, tetra-acylated and tri-acylated LPS induced lower levels of cytokines. These results suggest that the lipid A acylation pattern influences both the bacterial membrane permeability and innate immune stimulation. The results would be useful for redesigning the bacterial membrane structure and for developing lipid A vaccine adjuvant.
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Affiliation(s)
- Yanyan Li
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; E-Mails: (Y.L.); (Z.W.); (J.C.)
| | - Zhou Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; E-Mails: (Y.L.); (Z.W.); (J.C.)
| | - Jiuzhou Chen
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; E-Mails: (Y.L.); (Z.W.); (J.C.)
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, MD 21201, USA; E-Mail:
| | - Xiaoyuan Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; E-Mails: (Y.L.); (Z.W.); (J.C.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel./Fax: +86-510-8532-9239
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123
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Nchoutmboube JA, Viktorova EG, Scott AJ, Ford LA, Pei Z, Watkins PA, Ernst RK, Belov GA. Increased long chain acyl-Coa synthetase activity and fatty acid import is linked to membrane synthesis for development of picornavirus replication organelles. PLoS Pathog 2013; 9:e1003401. [PMID: 23762027 PMCID: PMC3675155 DOI: 10.1371/journal.ppat.1003401] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 04/19/2013] [Indexed: 12/20/2022] Open
Abstract
All positive strand (+RNA) viruses of eukaryotes replicate their genomes in association with membranes. The mechanisms of membrane remodeling in infected cells represent attractive targets for designing future therapeutics, but our understanding of this process is very limited. Elements of autophagy and/or the secretory pathway were proposed to be hijacked for building of picornavirus replication organelles. However, even closely related viruses differ significantly in their requirements for components of these pathways. We demonstrate here that infection with diverse picornaviruses rapidly activates import of long chain fatty acids. While in non-infected cells the imported fatty acids are channeled to lipid droplets, in infected cells the synthesis of neutral lipids is shut down and the fatty acids are utilized in highly up-regulated phosphatidylcholine synthesis. Thus the replication organelles are likely built from de novo synthesized membrane material, rather than from the remodeled pre-existing membranes. We show that activation of fatty acid import is linked to the up-regulation of cellular long chain acyl-CoA synthetase activity and identify the long chain acyl-CoA syntheatse3 (Acsl3) as a novel host factor required for polio replication. Poliovirus protein 2A is required to trigger the activation of import of fatty acids independent of its protease activity. Shift in fatty acid import preferences by infected cells results in synthesis of phosphatidylcholines different from those in uninfected cells, arguing that the viral replication organelles possess unique properties compared to the pre-existing membranes. Our data show how poliovirus can change the overall cellular membrane homeostasis by targeting one critical process. They explain earlier observations of increased phospholipid synthesis in infected cells and suggest a simple model of the structural development of the membranous scaffold of replication complexes of picorna-like viruses, that may be relevant for other (+)RNA viruses as well. Eukaryotic cells feature astonishing complexity of regulatory networks, yet control over this fine-tuned machinery is easily overrun by viruses with expression of just a handful of proteins. One of the striking examples of such hostile take-over is the rewiring of normal cellular membrane metabolism by (+)RNA viruses towards development of new membranous organelles harboring viral replication machinery. (+)RNA viruses of eukaryotes infect organisms from unicellular algae to humans. Many of them induce diseases resulting in significant economic losses, public health burden, human suffering and sometimes fatal consequences. We show how picornaviruses reorganize cellular lipid metabolism by targeting long chain acyl-CoA synthetase activity. This induces increased import of fatty acids in infected cells and up-regulation of phospholipid synthesis, resulting in formation of replication organelles different from the pre-existing cellular membranes. This mechanism is utilized by diverse viruses and may represent an attractive target for anti-viral interventions.
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Affiliation(s)
- Jules A. Nchoutmboube
- Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, Maryland, United States of America
| | - Ekaterina G. Viktorova
- Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, Maryland, United States of America
| | - Alison J. Scott
- University of Maryland, School of Dentistry, Baltimore, Maryland, United States of America
| | - Lauren A. Ford
- Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, Maryland, United States of America
| | - Zhengtong Pei
- Kennedy Krieger Institute and Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Paul A. Watkins
- Kennedy Krieger Institute and Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Robert K. Ernst
- University of Maryland, School of Dentistry, Baltimore, Maryland, United States of America
| | - George A. Belov
- Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, Maryland, United States of America
- * E-mail:
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Shirey KA, Lai W, Scott AJ, Lipsky M, Mistry P, Pletneva LM, Karp CL, McAlees J, Gioannini TL, Weiss J, Chen WH, Ernst RK, Rossignol DP, Gusovsky F, Blanco JCG, Vogel SN. The TLR4 antagonist Eritoran protects mice from lethal influenza infection. Nature 2013; 497:498-502. [PMID: 23636320 DOI: 10.1038/nature12118] [Citation(s) in RCA: 339] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 03/22/2013] [Indexed: 12/31/2022]
Abstract
There is a pressing need to develop alternatives to annual influenza vaccines and antiviral agents licensed for mitigating influenza infection. Previous studies reported that acute lung injury caused by chemical or microbial insults is secondary to the generation of host-derived, oxidized phospholipid that potently stimulates Toll-like receptor 4 (TLR4)-dependent inflammation. Subsequently, we reported that Tlr4(-/-) mice are highly refractory to influenza-induced lethality, and proposed that therapeutic antagonism of TLR4 signalling would protect against influenza-induced acute lung injury. Here we report that therapeutic administration of Eritoran (also known as E5564)-a potent, well-tolerated, synthetic TLR4 antagonist-blocks influenza-induced lethality in mice, as well as lung pathology, clinical symptoms, cytokine and oxidized phospholipid expression, and decreases viral titres. CD14 and TLR2 are also required for Eritoran-mediated protection, and CD14 directly binds Eritoran and inhibits ligand binding to MD2. Thus, Eritoran blockade of TLR signalling represents a novel therapeutic approach for inflammation associated with influenza, and possibly other infections.
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Affiliation(s)
- Kari Ann Shirey
- Department of Microbiology and Immunology, University of Maryland, Baltimore, Baltimore, Maryland 21201, USA
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125
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Affiliation(s)
- Daniel A Powell
- Department of Microbial Pathogenesis, University of Maryland-Baltimore, Baltimore, MD, USA
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126
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Hajjar AM, Ernst RK, Fortuno ES, Brasfield AS, Yam CS, Newlon LA, Kollmann TR, Miller SI, Wilson CB. Humanized TLR4/MD-2 mice reveal LPS recognition differentially impacts susceptibility to Yersinia pestis and Salmonella enterica. PLoS Pathog 2012; 8:e1002963. [PMID: 23071439 PMCID: PMC3469661 DOI: 10.1371/journal.ppat.1002963] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Accepted: 08/23/2012] [Indexed: 02/02/2023] Open
Abstract
Although lipopolysaccharide (LPS) stimulation through the Toll-like receptor (TLR)-4/MD-2 receptor complex activates host defense against Gram-negative bacterial pathogens, how species-specific differences in LPS recognition impact host defense remains undefined. Herein, we establish how temperature dependent shifts in the lipid A of Yersinia pestis LPS that differentially impact recognition by mouse versus human TLR4/MD-2 dictate infection susceptibility. When grown at 37°C, Y. pestis LPS is hypo-acylated and less stimulatory to human compared with murine TLR4/MD-2. By contrast, when grown at reduced temperatures, Y. pestis LPS is more acylated, and stimulates cells equally via human and mouse TLR4/MD-2. To investigate how these temperature dependent shifts in LPS impact infection susceptibility, transgenic mice expressing human rather than mouse TLR4/MD-2 were generated. We found the increased susceptibility to Y. pestis for "humanized" TLR4/MD-2 mice directly paralleled blunted inflammatory cytokine production in response to stimulation with purified LPS. By contrast, for other Gram-negative pathogens with highly acylated lipid A including Salmonella enterica or Escherichia coli, infection susceptibility and the response after stimulation with LPS were indistinguishable between mice expressing human or mouse TLR4/MD-2. Thus, Y. pestis exploits temperature-dependent shifts in LPS acylation to selectively evade recognition by human TLR4/MD-2 uncovered with "humanized" TLR4/MD-2 transgenic mice.
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Affiliation(s)
- Adeline M Hajjar
- Department of Comparative Medicine, University of Washington, Seattle, Washington, USA.
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127
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Yoon SH, Huang Y, Edgar JS, Ting YS, Heron SR, Kao Y, Li Y, Masselon CD, Ernst RK, Goodlett DR. Surface acoustic wave nebulization facilitating lipid mass spectrometric analysis. Anal Chem 2012; 84:6530-7. [PMID: 22742654 DOI: 10.1021/ac300807p] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Surface acoustic wave nebulization (SAWN) is a novel method to transfer nonvolatile analytes directly from the aqueous phase to the gas phase for mass spectrometric analysis. The lower ion energetics of SAWN and its planar nature make it appealing for analytically challenging lipid samples. This challenge is a result of their amphipathic nature, labile nature, and tendency to form aggregates, which readily precipitate clogging capillaries used for electrospray ionization (ESI). Here, we report the use of SAWN to characterize the complex glycolipid, lipid A, which serves as the membrane anchor component of lipopolysaccharide (LPS) and has a pronounced tendency to clog nano-ESI capillaries. We also show that unlike ESI SAWN is capable of ionizing labile phospholipids without fragmentation. Lastly, we compare the ease of use of SAWN to the more conventional infusion-based ESI methods and demonstrate the ability to generate higher order tandem mass spectral data of lipid A for automated structure assignment using our previously reported hierarchical tandem mass spectrometry (HiTMS) algorithm. The ease of generating SAWN-MS(n) data combined with HiTMS interpretation offers the potential for high throughput lipid A structure analysis.
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Affiliation(s)
- Sung Hwan Yoon
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195-7610, USA
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128
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Li Y, Powell DA, Shaffer SA, Rasko DA, Pelletier MR, Leszyk JD, Scott AJ, Masoudi A, Goodlett DR, Wang X, Raetz CRH, Ernst RK. LPS remodeling is an evolved survival strategy for bacteria. Proc Natl Acad Sci U S A 2012; 109:8716-21. [PMID: 22586119 PMCID: PMC3365160 DOI: 10.1073/pnas.1202908109] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Maintenance of membrane function is essential and regulated at the genomic, transcriptional, and translational levels. Bacterial pathogens have a variety of mechanisms to adapt their membrane in response to transmission between environment, vector, and human host. Using a well-characterized model of lipid A diversification (Francisella), we demonstrate temperature-regulated membrane remodeling directed by multiple alleles of the lipid A-modifying N-acyltransferase enzyme, LpxD. Structural analysis of the lipid A at environmental and host temperatures revealed that the LpxD1 enzyme added a 3-OH C18 acyl group at 37 °C (host), whereas the LpxD2 enzyme added a 3-OH C16 acyl group at 18 °C (environment). Mutational analysis of either of the individual Francisella lpxD genes altered outer membrane (OM) permeability, antimicrobial peptide, and antibiotic susceptibility, whereas only the lpxD1-null mutant was attenuated in mice and subsequently exhibited protection against a lethal WT challenge. Additionally, growth-temperature analysis revealed transcriptional control of the lpxD genes and posttranslational control of the LpxD1 and LpxD2 enzymatic activities. These results suggest a direct mechanism for LPS/lipid A-level modifications resulting in alterations of membrane fluidity, as well as integrity and may represent a general paradigm for bacterial membrane adaptation and virulence-state adaptation.
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Affiliation(s)
- Yanyan Li
- State Key Laboratory of Food Science and Technology, The Key Laboratory of Carbohydrate Chemistry and Biotechnology and Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214211, China
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, MD 21201
| | - Daniel A. Powell
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, MD 21201
| | - Scott A. Shaffer
- Departments of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605
| | - David A. Rasko
- Institute for Genome Sciences, Department of Microbiology and Immunology, University of Maryland, Baltimore, MD 21201
| | - Mark R. Pelletier
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, MD 21201
| | - John D. Leszyk
- Departments of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Alison J. Scott
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, MD 21201
| | - Ali Masoudi
- Department of Biochemistry, Duke University, Durham, NC 27710; and
| | - David R. Goodlett
- Department of Medicinal Chemistry, University of Washington, Seattle, WA 98195
| | - Xiaoyuan Wang
- State Key Laboratory of Food Science and Technology, The Key Laboratory of Carbohydrate Chemistry and Biotechnology and Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214211, China
| | | | - Robert K. Ernst
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, MD 21201
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129
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Galen JE, Simon R, Ernst RK. Salmonella expressing detoxified lipopolysaccharide is immunogenic and protective both as an attenuated vaccine and for delivery of foreign antigens. Expert Rev Vaccines 2012; 10:1679-82. [PMID: 22085171 DOI: 10.1586/erv.11.155] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The construction of safe and protective vaccines, derived from human pathogens that have been genetically modified to remove pathogenicity, is often easier to accomplish on paper than it is in the laboratory. Kong and colleagues have pursued a clever strategy to reduce the reactogenicity of attenuated Salmonella oral vaccines by genetically modifying the surface lipopolysaccharide to lower endotoxic activity. The resulting candidate vaccine strains were highly reduced in virulence yet were able to confer protection in a mouse model against challenge with virulent Salmonella. Remarkably, these strains could also be further modified to present foreign antigens from unrelated human pathogens and again confer protection against heterologous challenge. This work brings important new tools to bear on solving the problem of creating efficacious attenuated bacterial vaccines that maximize both safety and immunogenicity in clinical trials.
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Affiliation(s)
- James E Galen
- Center for Vaccine Development, University of Maryland, Baltimore, MD 21201, USA.
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130
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Scott A, Weldon S, Buchanan PJ, Schock B, Ernst RK, McAuley DF, Tunney MM, Irwin CR, Elborn JS, Taggart CC. Evaluation of the ability of LL-37 to neutralise LPS in vitro and ex vivo. PLoS One 2011; 6:e26525. [PMID: 22028895 PMCID: PMC3196584 DOI: 10.1371/journal.pone.0026525] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 09/28/2011] [Indexed: 11/26/2022] Open
Abstract
Background Human cathelicidin LL-37 is a cationic antimicrobial peptide (AMP) which possesses a variety of activities including the ability to neutralise endotoxin. In this study, we investigated the role of LPS neutralisation in mediating LL-37's ability to inhibit Pseudomonas aeruginosa LPS signalling in human monocytic cells. Methodology/Principal Findings Pre-treatment of monocytes with LL-37 significantly inhibited LPS-induced IL-8 production and the signalling pathway of associated transcription factors such as NF-κB. However, upon removal of LL-37 from the media prior to LPS stimulation, these inhibitory effects were abolished. These findings suggest that the ability of LL-37 to inhibit LPS signalling is largely dependent on extracellular LPS neutralisation. In addition, LL-37 potently inhibited cytokine production induced by LPS extracted from P. aeruginosa isolated from the lungs of cystic fibrosis (CF) patients. In the CF lung, polyanionic molecules such as glycosaminoglycans (GAGs) and DNA bind LL-37 and impact negatively on its antibacterial activity. In order to determine whether such interactions interfere with the LPS neutralising ability of LL-37, the status of LL-37 and its ability to bind LPS in CF sputum were investigated. Overall our findings suggest that in the CF lung, the ability of LL-37 to bind LPS and inhibit LPS-induced IL-8 production is attenuated as a result of binding to DNA and GAGs. However, LL-37 levels and its concomitant LPS-binding activity can be increased with a combination of DNase and GAG lyase (heparinase II) treatment. Conclusions/Significance Overall, these findings suggest that a deficiency in available LL-37 in the CF lung may contribute to greater LPS-induced inflammation during CF lung disease.
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Affiliation(s)
- Aaron Scott
- Centre for Infection and Immunity, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland
| | - Sinéad Weldon
- Centre for Infection and Immunity, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland
- * E-mail:
| | - Paul J. Buchanan
- Centre for Infection and Immunity, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland
| | - Bettina Schock
- Centre for Infection and Immunity, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, Maryland, United States of America
| | - Danny F. McAuley
- Centre for Infection and Immunity, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland
| | - Michael M. Tunney
- School of Pharmacy, Queen's University Belfast, Belfast, Northern Ireland
| | - Chris R. Irwin
- Centre for Dental Education, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland
| | - J. Stuart Elborn
- Centre for Infection and Immunity, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland
| | - Clifford C. Taggart
- Centre for Infection and Immunity, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland
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131
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Li Y, Wang X, Ernst RK. A rapid one-step method for the characterization of membrane lipid remodeling in Francisella using matrix-assisted laser desorption ionization time-of-flight tandem mass spectrometry. Rapid Commun Mass Spectrom 2011; 25:2641-2648. [PMID: 23657959 DOI: 10.1002/rcm.5168] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 06/21/2011] [Accepted: 06/29/2011] [Indexed: 06/02/2023]
Abstract
Lipids are essential components of all bacterial membranes. The most common membrane-associated lipids in Gram-negative bacteria are phospholipids and lipid A, the hydrophobic anchor of lipopolysaccharide. Diversity in these lipids arises through structural modifications that include changes in the length and location of fatty acids, and the addition of phosphate and carbohydrate moieties. Analysis of individual structural modifications normally requires large quantities of starting material and multiple methods for the isolation, hydrolysis, and analysis. In this study, we developed a novel one-step protocol for the combined isolation of phospholipids and lipid A from Francisella subspecies followed by analysis using matrix-assisted laser desorption ionization time-of-flight tandem mass spectrometry. The total time for lipid isolation and analysis was approximately 15 min and with a lower limit of detection of approximately 100 ng of purified lipid. This protocol identified the major lipid structures using both wild-type Ft subspecies strains and lipid A biosynthesis mutants. We also determined the relative levels of individual lipid A and phospholipids after growth under conditions that mimic the mammalian infection process. This analysis showed that the bacterial membranes remodeled rapidly to adapt to changes in environmental growth conditions and may be important for Francisella pathogenesis.
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Affiliation(s)
- Yanyan Li
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
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132
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Damron FH, Davis MR, Withers TR, Ernst RK, Goldberg JB, Yu G, Yu HD. Vanadate and triclosan synergistically induce alginate production by Pseudomonas aeruginosa strain PAO1. Mol Microbiol 2011; 81:554-70. [PMID: 21631603 DOI: 10.1111/j.1365-2958.2011.07715.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Alginate overproduction by P. aeruginosa strains, also known as mucoidy, is associated with chronic lung infections in cystic fibrosis (CF). It is not clear how alginate induction occurs in the wild-type (wt) mucA strains. When grown on Pseudomonas isolation agar (PIA), P. aeruginosa strains PAO1 and PA14 are non-mucoid, producing minimal amounts of alginate. Here we report the addition of ammonium metavanadate (AMV), a phosphatase inhibitor, to PIA (PIA-AMV) induced mucoidy in both these laboratory strains and early lung colonizing non-mucoid isolates with a wt mucA. This phenotypic switch was reversible depending on the availability of vanadate salts and triclosan, a component of PIA. Alginate induction in PAO1 on PIA-AMV was correlated with increased proteolytic degradation of MucA, and required envelope proteases AlgW or MucP, and a two-component phosphate regulator, PhoP. Other changes included the addition of palmitate to lipid A, a phenotype also observed in chronic CF isolates. Proteomic analysis revealed the upregulation of stress chaperones, which was confirmed by increased expression of the chaperone/protease MucD. Altogether, these findings suggest a model of alginate induction and the PIA-AMV medium may be suitable for examining early lung colonization phenotypes in CF before the selection of the mucA mutants.
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Affiliation(s)
- F Heath Damron
- Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine at Marshall University, Huntington, WV 25755-9320, USA
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133
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Ting YS, Shaffer SA, Jones JW, Ng WV, Ernst RK, Goodlett DR. Automated lipid A structure assignment from hierarchical tandem mass spectrometry data. J Am Soc Mass Spectrom 2011; 22:856-866. [PMID: 21472520 DOI: 10.1007/s13361-010-0055-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Revised: 12/10/2010] [Accepted: 12/10/2010] [Indexed: 05/30/2023]
Abstract
Infusion-based electrospray ionization (ESI) coupled to multiple-stage tandem mass spectrometry (MS(n)) is a standard methodology for investigating lipid A structural diversity (Shaffer et al. J. Am. Soc. Mass. Spectrom. 18(6), 1080-1092, 2007). Annotation of these MS(n) spectra, however, has remained a manual, expert-driven process. In order to keep up with the data acquisition rates of modern instruments, we devised a computational method to annotate lipid A MS(n) spectra rapidly and automatically, which we refer to as hierarchical tandem mass spectrometry (HiTMS) algorithm. As a first-pass tool, HiTMS aids expert interpretation of lipid A MS(n ) data by providing the analyst with a set of candidate structures that may then be confirmed or rejected. HiTMS deciphers the signature ions (e.g., A-, Y-, and Z-type ions) and neutral losses of MS(n) spectra using a species-specific library based on general prior structural knowledge of the given lipid A species under investigation. Candidates are selected by calculating the correlation between theoretical and acquired MS(n) spectra. At a false discovery rate of less than 0.01, HiTMS correctly assigned 85% of the structures in a library of 133 manually annotated Francisella tularensis subspecies novicida lipid A structures. Additionally, HiTMS correctly assigned 85% of the structures in a smaller library of lipid A species from Yersinia pestis demonstrating that it may be used across species.
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Affiliation(s)
- Ying S Ting
- Department of Medicinal Chemistry, University of Washington, Box 357610, Seattle, WA 98195-7610, USA
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134
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Jassem AN, Zlosnik JEA, Henry DA, Hancock REW, Ernst RK, Speert DP. In vitro susceptibility of Burkholderia vietnamiensis to aminoglycosides. Antimicrob Agents Chemother 2011; 55:2256-64. [PMID: 21321142 PMCID: PMC3088185 DOI: 10.1128/aac.01434-10] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2010] [Accepted: 02/01/2011] [Indexed: 11/20/2022] Open
Abstract
Burkholderia cepacia complex (BCC) bacteria are opportunistic pathogens that can cause severe disease in cystic fibrosis (CF) patients and other immunocompromised individuals and are typically multidrug resistant. Here we observed that unlike other BCC species, most environmental and clinical Burkholderia vietnamiensis isolates were intrinsically susceptible to aminoglycosides but not to cationic antimicrobial peptides or polymyxin B. Furthermore, strains acquired aminoglycoside resistance during chronic CF infection, a phenomenon that could be induced under tobramycin or azithromycin pressure in vitro. In comparing susceptible and resistant B. vietnamiensis isolates, no gross differences in lipopolysaccharide structure were observed, all had lipid A-associated 4-amino-4-deoxy-L-arabinose residues, and all were resistant to the permeabilizing effects of aminoglycosides, a measure of drug entry via self-promoted uptake. However, susceptible isolates accumulated 5 to 6 times more gentamicin than a resistant isolate, and aminoglycoside susceptibility increased in the presence of an efflux pump inhibitor. B. vietnamiensis is therefore unusual among BCC bacteria in its susceptibility to aminoglycosides and capacity to acquire resistance. Aminoglycoside resistance appears to be due to decreased cellular accumulation as a result of active efflux.
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Affiliation(s)
- Agatha N. Jassem
- Departments of Pathology and Laboratory Medicine
- Centre for Understanding and Preventing Infection in Children, University of British Columbia, Vancouver, British Columbia, Canada
| | - James E. A. Zlosnik
- Pediatrics
- Centre for Understanding and Preventing Infection in Children, University of British Columbia, Vancouver, British Columbia, Canada
| | - Deborah A. Henry
- Pediatrics
- Centre for Understanding and Preventing Infection in Children, University of British Columbia, Vancouver, British Columbia, Canada
| | - Robert E. W. Hancock
- Department of Microbiology and Immunology and Centre for Microbial Diseases and Immunity Research, University of British Columbia, Vancouver, British Columbia, Canada
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, University of Maryland—Baltimore, Baltimore, Maryland
| | - David P. Speert
- Departments of Pathology and Laboratory Medicine
- Pediatrics
- Centre for Understanding and Preventing Infection in Children, University of British Columbia, Vancouver, British Columbia, Canada
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Soni S, Ernst RK, Muszyński A, Mohapatra NP, Perry MB, Vinogradov E, Carlson RW, Gunn JS. Francisella tularensis blue-gray phase variation involves structural modifications of lipopolysaccharide o-antigen, core and lipid a and affects intramacrophage survival and vaccine efficacy. Front Microbiol 2010; 1:129. [PMID: 21687776 PMCID: PMC3109528 DOI: 10.3389/fmicb.2010.00129] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 10/28/2010] [Indexed: 11/13/2022] Open
Abstract
Francisella tularensis is a CDC Category A biological agent and a potential bioterrorist threat. There is no licensed vaccine against tularemia in the United States. A long-standing issue with potential Francisella vaccines is strain phase variation to a gray form that lacks protective capability in animal models. Comparisons of the parental strain (LVS) and a gray variant (LVSG) have identified lipopolysaccharide (LPS) alterations as a primary change. The LPS of the F. tularensis variant strain gains reactivity to F. novicida anti-LPS antibodies, suggesting structural alterations to the O-antigen. However, biochemical and structural analysis of the F. tularensis LVSG and LVS LPS demonstrated that LVSG has less O-antigen but no major O-antigen structural alterations. Additionally, LVSG possesses structural differences in both the core and lipid A regions, the latter being decreased galactosamine modification. Recent work has identified two genes important in adding galactosamine (flmF2 and flmK) to the lipid A. Quantitative real-time PCR showed reduced transcripts of both of these genes in the gray variant when compared to LVS. Loss of flmF2 or flmK caused less frequent phase conversion but did not alter intramacrophage survival or colony morphology. The LVSG strain demonstrated an intramacrophage survival defect in human and rat but not mouse macrophages. Consistent with this result, the LVSG variant demonstrated little change in LD50 in the mouse model of infection. Furthermore, the LVSG strain lacks the protective capacity of F. tularensis LVS against virulent Type A challenge. These data suggest that the LPS of the F. tularensis LVSG phase variant is dramatically altered. Understanding the mechanism of blue to gray phase variation may lead to a way to inhibit this variation, thus making future F. tularensis vaccines more stable and efficacious.
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Affiliation(s)
- Shilpa Soni
- Center for Microbial Interface Biology, Department of Molecular Virology, Immunology and Medical Genetics, and Department of Internal Medicine, Division of Infectious Diseases, The Ohio State University Columbus, OH, USA
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Lai XH, Shirley RL, Crosa L, Kanistanon D, Tempel R, Ernst RK, Gallagher LA, Manoil C, Heffron F. Mutations of Francisella novicida that alter the mechanism of its phagocytosis by murine macrophages. PLoS One 2010; 5:e11857. [PMID: 20686600 PMCID: PMC2912274 DOI: 10.1371/journal.pone.0011857] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Accepted: 06/29/2010] [Indexed: 12/15/2022] Open
Abstract
Infection with the bacterial pathogen Francisella tularensis tularensis (F. tularensis) causes tularemia, a serious and debilitating disease. Francisella tularensis novicida strain U112 (abbreviated F. novicida), which is closely related to F. tularensis, is pathogenic for mice but not for man, making it an ideal model system for tularemia. Intracellular pathogens like Francisella inhibit the innate immune response, thereby avoiding immune recognition and death of the infected cell. Because activation of inflammatory pathways may lead to cell death, we reasoned that we could identify bacterial genes involved in inhibiting inflammation by isolating mutants that killed infected cells faster than the wild-type parent. We screened a comprehensive transposon library of F. novicida for mutant strains that increased the rate of cell death following infection in J774 macrophage-like cells, as compared to wild-type F. novicida. Mutations in 28 genes were identified as being hypercytotoxic to both J774 and primary macrophages of which 12 were less virulent in a mouse infection model. Surprisingly, we found that F. novicida with mutations in four genes (lpcC, manB, manC and kdtA) were taken up by and killed macrophages at a much higher rate than the parent strain, even upon treatment with cytochalasin D (cytD), a classic inhibitor of macrophage phagocytosis. At least 10-fold more mutant bacteria were internalized by macrophages as compared to the parent strain if the bacteria were first fixed with formaldehyde, suggesting a surface structure is required for the high phagocytosis rate. However, bacteria were required to be viable for macrophage toxicity. The four mutant strains do not make a complete LPS but instead have an exposed lipid A. Interestingly, other mutations that result in an exposed LPS core were not taken up at increased frequency nor did they kill host cells more than the parent. These results suggest an alternative, more efficient macrophage uptake mechanism for Francisella that requires exposure of a specific bacterial surface structure(s) but results in increased cell death following internalization of live bacteria.
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Affiliation(s)
- Xin-He Lai
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, United States of America
- Virogenomics, Inc., Tigard, Oregon, United States of America
- * E-mail: (X-HL); (FH)
| | | | - Lidia Crosa
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Duangjit Kanistanon
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, Maryland, United States of America
| | - Rebecca Tempel
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, Maryland, United States of America
| | - Larry A. Gallagher
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Colin Manoil
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Fred Heffron
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, United States of America
- * E-mail: (X-HL); (FH)
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137
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Jones JW, Cohen IE, Tureĉek F, Goodlett DR, Ernst RK. Comprehensive structure characterization of lipid A extracted from Yersinia pestis for determination of its phosphorylation configuration. J Am Soc Mass Spectrom 2010; 21:785-799. [PMID: 20185334 DOI: 10.1016/j.jasms.2010.01.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Revised: 01/08/2010] [Accepted: 01/08/2010] [Indexed: 05/28/2023]
Abstract
We report on comprehensive structure characterization of lipid A extracted from Yersinia pestis (Yp) for determination of its phosphorylation configuration that was achieved by combining the methods of molecular biology with high-resolution tandem mass spectrometry. The phosphorylation pattern of diphosphorylated lipid A extracted from Yp has recently been found to be a heterogeneous mixture of C-1 and C-4' bisphosphate, C-1 pyrophosphate, and C-4' pyrophosphate (Proc. Natl. Acad. Sci. 2008, 105, 12742). To reduce the inherent phosphate heterogeneity of diphosphorylated lipid A extracted from Yp, we incorporated specific C-1 and C-4' position phosphatases into wild type KIM6+ Yp grown at 37 degrees C. Comprehensive high-resolution tandem mass spectrometric analyses of lipid A extracted from Yp modified with either the C-1 or C-4' phosphatase allowed for unambiguous structure assignment of monophosphorylated and diphosphorylated lipid A and distinction of isomeric bisphosphate and pyrophosphate forms. The prevalent aminoarabinose modification was determined to be exclusively attached to the lipid A disaccharide via a phospho-diester linkage at either or both the C-1 and C-4' positions.
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Affiliation(s)
- Jace W Jones
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, USA
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138
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Abstract
Pseudomonas aeruginosa (PA) is a ubiquitous environmental Gram-negative bacterium found in soil and water. This opportunistic pathogen can cause infections in individuals with impaired phagocytic function, such as those with burns, exposure to chemotherapy, or cystic fibrosis (CF). PA infects the lungs of most individuals with CF, and is associated with severe progressive pulmonary disease that is the major cause of premature death in this disorder. The specific adaptations of PA to the CF airway responsible for bacterial persistence and antibiotic tolerance are not completely understood but may include increased alginate production (i.e., mucoid phenotype), biofilm formation, and specific lipid A modifications. During adaptation to the CF airway, PA synthesizes a variety of lipid A structures that alter host innate immune responses and promote bacterial persistence and chronic infection. The synthesis of specific lipid A structures is attributable to bacterial enzymes that: (1) remove the 3OH-C10:0 acyl chain from the 3-position (PagL); (2) add a C16:0 acyl chain to the 3OH-C10:0 chain at the 3'-position (PagP); (3) add C12:0 and 2OH-C12:0 acyl chains to the 3OH-C12:0 chains at the 2- and 2'-positions (HtrB and LpxO); and (4) add aminoarabinose to phosphate groups at the 1- and 4'-positions (PmrH, PmrF, PmrI, PmrJ, PmrK, and PmrE). These lipid A modifications represent an essential aspect of PA adaptation to the CF airway.
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Affiliation(s)
- Samuel M Moskowitz
- Simches Research Center, Massachusetts General Hospital, 185 Cambridge Street, CPZN-3-830, Boston, MA, 02114, USA
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139
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Pilonieta MC, Erickson KD, Ernst RK, Detweiler CS. A protein important for antimicrobial peptide resistance, YdeI/OmdA, is in the periplasm and interacts with OmpD/NmpC. J Bacteriol 2009; 191:7243-52. [PMID: 19767429 PMCID: PMC2786563 DOI: 10.1128/jb.00688-09] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Accepted: 09/10/2009] [Indexed: 01/02/2023] Open
Abstract
Antimicrobial peptides (AMPs) kill or prevent the growth of microbes. AMPs are made by virtually all single and multicellular organisms and are encountered by bacteria in diverse environments, including within a host. Bacteria use sensor-kinase systems to respond to AMPs or damage caused by AMPs. Salmonella enterica deploys at least three different sensor-kinase systems to modify gene expression in the presence of AMPs: PhoP-PhoQ, PmrA-PmrB, and RcsB-RcsC-RcsD. The ydeI gene is regulated by the RcsB-RcsC-RcsD pathway and encodes a 14-kDa predicted oligosaccharide/oligonucleotide binding-fold (OB-fold) protein important for polymyxin B resistance in broth and also for virulence in mice. We report here that ydeI is additionally regulated by the PhoP-PhoQ and PmrA-PmrB sensor-kinase systems, which confer resistance to cationic AMPs by modifying lipopolysaccharide (LPS). ydeI, however, is not important for known LPS modifications. Two independent biochemical methods found that YdeI copurifies with OmpD/NmpC, a member of the trimeric beta-barrel outer membrane general porin family. Genetic analysis indicates that ompD contributes to polymyxin B resistance, and both ydeI and ompD are important for resistance to cathelicidin antimicrobial peptide, a mouse AMP produced by multiple cell types and expressed in the gut. YdeI localizes to the periplasm, where it could interact with OmpD. A second predicted periplasmic OB-fold protein, YgiW, and OmpF, another general porin, also contribute to polymyxin B resistance. Collectively, the data suggest that periplasmic OB-fold proteins can interact with porins to increase bacterial resistance to AMPs.
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Affiliation(s)
- M. Carolina Pilonieta
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, University of Maryland-Baltimore, Department of Microbial Pathogenesis, School of Dentistry, Baltimore, Maryland 21201
| | - Kimberly D. Erickson
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, University of Maryland-Baltimore, Department of Microbial Pathogenesis, School of Dentistry, Baltimore, Maryland 21201
| | - Robert K. Ernst
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, University of Maryland-Baltimore, Department of Microbial Pathogenesis, School of Dentistry, Baltimore, Maryland 21201
| | - Corrella S. Detweiler
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, University of Maryland-Baltimore, Department of Microbial Pathogenesis, School of Dentistry, Baltimore, Maryland 21201
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Coats SR, Jones JW, Do CT, Braham PH, Bainbridge BW, To TT, Goodlett DR, Ernst RK, Darveau RP. Human Toll-like receptor 4 responses to P. gingivalis are regulated by lipid A 1- and 4'-phosphatase activities. Cell Microbiol 2009; 11:1587-99. [PMID: 19552698 DOI: 10.1111/j.1462-5822.2009.01349.x] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Signal transduction following binding of lipopolysaccharide (LPS) to Toll-like receptor 4 (TLR4) is an essential aspect of host innate immune responses to infection by Gram-negative pathogens. Here, we describe a novel molecular mechanism used by a prevalent human bacterial pathogen to evade and subvert the human innate immune system. We show that the oral pathogen, Porphyromonas gingivalis, uses endogenous lipid A 1- and 4'-phosphatase activities to modify its LPS, creating immunologically silent, non-phosphorylated lipid A. This unique lipid A provides a highly effective mechanism employed by this bacterium to evade TLR4 sensing and to resist killing by cationic antimicrobial peptides. In addition, lipid A 1-phosphatase activity is suppressed by haemin, an important nutrient in the oral cavity. Specifically, P. gingivalis grown in the presence of high haemin produces lipid A that acts as a potent TLR4 antagonist. These results suggest that haemin-dependent regulation of lipid A 1-dephosphorylation can shift P. gingivalis lipid A activity from TLR4 evasive to TLR4 suppressive, potentially altering critical interactions between this bacterium, the local microbial community and the host innate immune system.
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Affiliation(s)
- Stephen R Coats
- Department of Periodontics, School of Dentistry, University of Washington, 1959 NE Pacific St., Seattle, WA 98195-7444, USA.
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141
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Kalhorn TF, Kiavand A, Cohen IE, Nelson AK, Ernst RK. A sensitive liquid chromatography/mass spectrometry-based assay for quantitation of amino-containing moieties in lipid A. Rapid Commun Mass Spectrom 2009; 23:433-42. [PMID: 19130491 PMCID: PMC2716696 DOI: 10.1002/rcm.3900] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A novel sensitive liquid chromatography/mass spectrometry-based assay was developed for the quantitation of aminosugars, including 2-amino-2-deoxyglucose (glucosamine, GlcN), 2-amino-2-deoxygalactose (galactosamine, GalN), and 4-amino-4-deoxyarabinose (aminoarabinose, AraN), and for ethanolamine (EtN), present in lipid A. This assay enables the identification and quantitation of all amino-containing moieties present in lipopolysaccharide or lipid A from a single sample. The method was applied to the analysis of lipid A (endotoxin) isolated from a variety of biosynthetic and regulatory mutants of Salmonella enterica serovar Typhimurium and Francisella tularensis subspecies novicida. Lipid A is treated with trifluoroacetic acid to liberate and deacetylate individual aminosugars and mass tagged with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate, which reacts with primary and secondary amines. The derivatives are separated using reversed-phase chromatography and analyzed using a single quadrupole mass spectrometer to detect quantities as small as 20 fmol. GalN was detected only in Francisella and AraN only in Salmonella, while GlcN was detected in lipid A samples from both species of bacteria. Additionally, we found an approximately 10-fold increase in the level of AraN in lipid A isolated from Salmonella grown in magnesium-limited versus magnesium-replete conditions. Salmonella with defined mutations in lipid A synthesis and regulatory genes were used to further validate the assay. Salmonella with null mutations in the phoP, pmrE, and prmF genes were unable to add AraN to their lipid A, while Salmonella with constitutively active phoP and pmrA exhibited AraN modification of lipid A even in the normally repressive magnesium-replete growth condition. The described assay produces excellent repeatability and reproducibility for the detection of amino-containing moieties in lipid A from a variety of bacterial sources.
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Affiliation(s)
- Thomas F. Kalhorn
- Department of Medicinal Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Anahita Kiavand
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Ilana E. Cohen
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Amanda K. Nelson
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Robert K. Ernst
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, MD 21201, USA
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142
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West TE, Ernst RK, Jansson-Hutson MJ, Skerrett SJ. Activation of Toll-like receptors by Burkholderia pseudomallei. BMC Immunol 2008; 9:46. [PMID: 18691413 PMCID: PMC2527550 DOI: 10.1186/1471-2172-9-46] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Accepted: 08/08/2008] [Indexed: 12/13/2022] Open
Abstract
Background Melioidosis, a lethal tropical infection that is endemic in southeast Asia and northern Australia, is caused by the saprophytic Gram-negative bacterium Burkholderia pseudomallei. Overall mortality approaches 40% yet little is known about mechanisms of host defense. Toll-like receptors (TLRs) are host transmembrane receptors that recognize conserved pathogen molecular patterns and induce an inflammatory response. The lipopolysaccharide (LPS) of Gram-negative bacteria is a potent inducer of the host innate immune system. TLR4, in association with MD-2, is the archetype receptor for LPS although B. pseudomallei LPS has been previously identified as a TLR2 agonist. We examined TLR signaling induced by B. pseudomallei, B. pseudomallei LPS, and B. pseudomallei lipid A using gain-of-function transfection assays of NF-κB activation and studies of TLR-deficient macrophages. Results In HEK293 cells transfected with murine or human TLRs, CD14, and MD-2, heat-killed B. pseudomallei activated TLR2 (in combination with TLR1 or TLR6) and TLR4. B. pseudomallei LPS and lipid A activated TLR4 and this TLR4-mediated signaling required MD-2. In TLR2-/- macrophages, stimulation with heat-killed B. pseudomallei augmented TNF-α and MIP-2 production whereas in TLR4-/- cells, TNF-α, MIP-2, and IL-10 production was reduced. Cytokine production by macrophages stimulated with B. pseudomallei LPS or lipid A was entirely dependent on TLR4 but was increased in the absence of TLR2. TLR adaptor molecule MyD88 strongly regulated TNF-α production in response to heat-killed B. pseudomallei. Conclusion B. pseudomallei activates TLR2 and TLR4. In the presence of MD-2, B. pseudomallei LPS and lipid A are TLR4 ligands. Although the macrophage cytokine response to B. pseudomallei LPS or lipid A is completely dependent on TLR4, in TLR2-/- macrophages stimulated with B. pseudomallei, B. pseudomallei LPS or lipid A, cytokine production is augmented. Other MyD88-dependent signaling pathways may also be important in the host response to B. pseudomallei infection. These findings provide new insights into critical mechanisms of host defense in melioidosis.
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Affiliation(s)
- T Eoin West
- Department of Medicine, University of Washington, Seattle, Washington, USA.
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143
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Kanistanon D, Hajjar AM, Pelletier MR, Gallagher LA, Kalhorn T, Shaffer SA, Goodlett DR, Rohmer L, Brittnacher MJ, Skerrett SJ, Ernst RK. A Francisella mutant in lipid A carbohydrate modification elicits protective immunity. PLoS Pathog 2008; 4:e24. [PMID: 18266468 PMCID: PMC2233673 DOI: 10.1371/journal.ppat.0040024] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2007] [Accepted: 12/21/2007] [Indexed: 11/18/2022] Open
Abstract
Francisella tularensis (Ft) is a highly infectious Gram-negative bacterium and the causative agent of the human disease tularemia. Ft is designated a class A select agent by the Centers for Disease Control and Prevention. Human clinical isolates of Ft produce lipid A of similar structure to Ft subspecies novicida (Fn), a pathogen of mice. We identified three enzymes required for Fn lipid A carbohydrate modifications, specifically the presence of mannose (flmF1), galactosamine (flmF2), or both carbohydrates (flmK). Mutants lacking either galactosamine (flmF2) or galactosamine/mannose (flmK) addition to their lipid A were attenuated in mice by both pulmonary and subcutaneous routes of infection. In addition, aerosolization of the mutants (flmF2 and flmK) provided protection against challenge with wild-type (WT) Fn, whereas subcutaneous administration of only the flmK mutant provided protection from challenge with WT Fn. Furthermore, infection of an alveolar macrophage cell line by the flmK mutant induced higher levels of tumor necrosis factor-α (TNF-α) and macrophage inhibitory protein-2 (MIP-2) when compared to infection with WT Fn. Bone marrow–derived macrophages (BMMø) from Toll-like receptor 4 (TLR4) and TLR2/4 knockout mice infected with the flmK mutant also produced significantly higher amounts of interleukin-6 (IL-6) and MIP-2 than BMMø infected with WT Fn. However, production of IL-6 and MIP-2 was undetectable in BMMø from MyD88−/− mice infected with either strain. MyD88−/− mice were also susceptible to flmK mutant infection. We hypothesize that the ability of the flmK mutant to activate pro-inflammatory cytokine/chemokine production and innate immune responses mediated by the MyD88 signaling pathway may be responsible for its attenuation, leading to the induction of protective immunity by this mutant. Bacterial pathogens modify outer membrane components, such as lipid A or endotoxin, the lipid anchor of lipopolysaccharide, to enhance the ability to colonize, spread to different tissues, and/or avoid the host's immune defenses. Lipopolysaccharide also plays an essential role in maintaining membrane integrity and is a key factor in host innate immune recognition of Gram-negative bacterial infections. Francisella tularensis is the causative agent of the human disease tularemia and is classified as a category A select agent. Francisella novicida (Fn) is the murine counterpart of F. tularensis. The structure of Francisella spp. lipid A is unique in that it is modified by various carbohydrates that play a role in virulence and altered endotoxicity. In our study, we identified and defined the role of three genes involved in the carbohydrate modification of the base Fn lipid A structure. We showed that the lack of specific modification(s) of the Fn lipid A molecule lead to bacterial attenuation and activation of a protective immune response against a lethal wild-type infection. Therefore, alteration of Francisella lipid A structure may represent a pathogenesis strategy common to the Francisella species, and specific lipid A mutant strains may be candidates for inclusion in future vaccine studies.
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Affiliation(s)
- Duangjit Kanistanon
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
- Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Adeline M Hajjar
- Department of Immunology, University of Washington, Seattle, Washington, United States of America
| | - Mark R Pelletier
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Larry A Gallagher
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Thomas Kalhorn
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, United States of America
| | - Scott A Shaffer
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, United States of America
| | - David R Goodlett
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, United States of America
| | - Laurence Rohmer
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Mitchell J Brittnacher
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Shawn J Skerrett
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Robert K Ernst
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
- * To whom correspondence should be addressed. E-mail:
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144
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Rohmer L, Fong C, Abmayr S, Wasnick M, Larson Freeman TJ, Radey M, Guina T, Svensson K, Hayden HS, Jacobs M, Gallagher LA, Manoil C, Ernst RK, Drees B, Buckley D, Haugen E, Bovee D, Zhou Y, Chang J, Levy R, Lim R, Gillett W, Guenthener D, Kang A, Shaffer SA, Taylor G, Chen J, Gallis B, D'Argenio DA, Forsman M, Olson MV, Goodlett DR, Kaul R, Miller SI, Brittnacher MJ. Comparison of Francisella tularensis genomes reveals evolutionary events associated with the emergence of human pathogenic strains. Genome Biol 2008; 8:R102. [PMID: 17550600 PMCID: PMC2394750 DOI: 10.1186/gb-2007-8-6-r102] [Citation(s) in RCA: 199] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2006] [Revised: 03/02/2007] [Accepted: 06/05/2007] [Indexed: 01/04/2023] Open
Abstract
.Sequencing of the non-pathogenic Francisella tularensis sub-species novicida U112, and comparison with two pathogenic sub-species, provides insights into the evolution of pathogenicity in these species. Background Francisella tularensis subspecies tularensis and holarctica are pathogenic to humans, whereas the two other subspecies, novicida and mediasiatica, rarely cause disease. To uncover the factors that allow subspecies tularensis and holarctica to be pathogenic to humans, we compared their genome sequences with the genome sequence of Francisella tularensis subspecies novicida U112, which is nonpathogenic to humans. Results Comparison of the genomes of human pathogenic Francisella strains with the genome of U112 identifies genes specific to the human pathogenic strains and reveals pseudogenes that previously were unidentified. In addition, this analysis provides a coarse chronology of the evolutionary events that took place during the emergence of the human pathogenic strains. Genomic rearrangements at the level of insertion sequences (IS elements), point mutations, and small indels took place in the human pathogenic strains during and after differentiation from the nonpathogenic strain, resulting in gene inactivation. Conclusion The chronology of events suggests a substantial role for genetic drift in the formation of pseudogenes in Francisella genomes. Mutations that occurred early in the evolution, however, might have been fixed in the population either because of evolutionary bottlenecks or because they were pathoadaptive (beneficial in the context of infection). Because the structure of Francisella genomes is similar to that of the genomes of other emerging or highly pathogenic bacteria, this evolutionary scenario may be shared by pathogens from other species.
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Affiliation(s)
- Laurence Rohmer
- Department of Genome Sciences, University of Washington, Campus Box 357710, 1705 NE Pacific street Seattle, Washington 98195, USA
| | - Christine Fong
- Department of Genome Sciences, University of Washington, Campus Box 357710, 1705 NE Pacific street Seattle, Washington 98195, USA
| | - Simone Abmayr
- Department of Genome Sciences, University of Washington, Campus Box 357710, 1705 NE Pacific street Seattle, Washington 98195, USA
| | - Michael Wasnick
- Department of Genome Sciences, University of Washington, Campus Box 357710, 1705 NE Pacific street Seattle, Washington 98195, USA
| | - Theodore J Larson Freeman
- Department of Genome Sciences, University of Washington, Campus Box 357710, 1705 NE Pacific street Seattle, Washington 98195, USA
| | - Matthew Radey
- Department of Genome Sciences, University of Washington, Campus Box 357710, 1705 NE Pacific street Seattle, Washington 98195, USA
| | - Tina Guina
- Department of Pediatrics, Division of Infectious Diseases, University of Washington, Campus Box 357710, 1720 NE Pacific street, Seattle, Washington 98195, USA
| | - Kerstin Svensson
- NBC Analysis, Division of NBC Defence, Swedish Defence Research Agency, SE-901 82 Umeå, Sweden
- Department of Clinical Microbiology, Infectious Diseases, Umeå University, SE-901 85 Umeå, Sweden
| | - Hillary S Hayden
- University of Washington Genome Center, University of Washington, Campus Box 352145, Mason Road, Seattle, Washington 98195, USA
| | - Michael Jacobs
- University of Washington Genome Center, University of Washington, Campus Box 352145, Mason Road, Seattle, Washington 98195, USA
| | - Larry A Gallagher
- Department of Genome Sciences, University of Washington, Campus Box 357710, 1705 NE Pacific street Seattle, Washington 98195, USA
| | - Colin Manoil
- Department of Genome Sciences, University of Washington, Campus Box 357710, 1705 NE Pacific street Seattle, Washington 98195, USA
| | - Robert K Ernst
- Department Medicine, University of Washington, Seattle, Washington 98195, USA
| | - Becky Drees
- Department of Microbiology, University of Washington, Box 357242, 1720 NE Pacific street, Seattle, Washington 98195, USA
| | - Danielle Buckley
- University of Washington Genome Center, University of Washington, Campus Box 352145, Mason Road, Seattle, Washington 98195, USA
| | - Eric Haugen
- University of Washington Genome Center, University of Washington, Campus Box 352145, Mason Road, Seattle, Washington 98195, USA
| | - Donald Bovee
- University of Washington Genome Center, University of Washington, Campus Box 352145, Mason Road, Seattle, Washington 98195, USA
| | - Yang Zhou
- University of Washington Genome Center, University of Washington, Campus Box 352145, Mason Road, Seattle, Washington 98195, USA
| | - Jean Chang
- University of Washington Genome Center, University of Washington, Campus Box 352145, Mason Road, Seattle, Washington 98195, USA
| | - Ruth Levy
- University of Washington Genome Center, University of Washington, Campus Box 352145, Mason Road, Seattle, Washington 98195, USA
| | - Regina Lim
- University of Washington Genome Center, University of Washington, Campus Box 352145, Mason Road, Seattle, Washington 98195, USA
| | - Will Gillett
- University of Washington Genome Center, University of Washington, Campus Box 352145, Mason Road, Seattle, Washington 98195, USA
| | - Don Guenthener
- University of Washington Genome Center, University of Washington, Campus Box 352145, Mason Road, Seattle, Washington 98195, USA
| | - Allison Kang
- University of Washington Genome Center, University of Washington, Campus Box 352145, Mason Road, Seattle, Washington 98195, USA
| | - Scott A Shaffer
- Department of Medicinal Chemistry, Box 357610, University of Washington, Seattle, Washington 98195, USA
| | - Greg Taylor
- Department of Medicinal Chemistry, Box 357610, University of Washington, Seattle, Washington 98195, USA
| | - Jinzhi Chen
- Department of Medicinal Chemistry, Box 357610, University of Washington, Seattle, Washington 98195, USA
| | - Byron Gallis
- Department of Medicinal Chemistry, Box 357610, University of Washington, Seattle, Washington 98195, USA
| | - David A D'Argenio
- Department of Microbiology, University of Washington, Box 357242, 1720 NE Pacific street, Seattle, Washington 98195, USA
| | - Mats Forsman
- NBC Analysis, Division of NBC Defence, Swedish Defence Research Agency, SE-901 82 Umeå, Sweden
| | - Maynard V Olson
- Department of Genome Sciences, University of Washington, Campus Box 357710, 1705 NE Pacific street Seattle, Washington 98195, USA
- University of Washington Genome Center, University of Washington, Campus Box 352145, Mason Road, Seattle, Washington 98195, USA
- Department Medicine, University of Washington, Seattle, Washington 98195, USA
| | - David R Goodlett
- Department of Medicinal Chemistry, Box 357610, University of Washington, Seattle, Washington 98195, USA
| | - Rajinder Kaul
- University of Washington Genome Center, University of Washington, Campus Box 352145, Mason Road, Seattle, Washington 98195, USA
- Department Medicine, University of Washington, Seattle, Washington 98195, USA
| | - Samuel I Miller
- Department of Genome Sciences, University of Washington, Campus Box 357710, 1705 NE Pacific street Seattle, Washington 98195, USA
- Department Medicine, University of Washington, Seattle, Washington 98195, USA
- Department of Microbiology, University of Washington, Box 357242, 1720 NE Pacific street, Seattle, Washington 98195, USA
| | - Mitchell J Brittnacher
- Department of Genome Sciences, University of Washington, Campus Box 357710, 1705 NE Pacific street Seattle, Washington 98195, USA
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145
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Ernst RK, Moskowitz SM, Emerson JC, Kraig GM, Adams KN, Harvey MD, Ramsey B, Speert DP, Burns JL, Miller SI. Unique lipid a modifications in Pseudomonas aeruginosa isolated from the airways of patients with cystic fibrosis. J Infect Dis 2007; 196:1088-92. [PMID: 17763333 PMCID: PMC2723782 DOI: 10.1086/521367] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Accepted: 05/08/2007] [Indexed: 12/17/2022] Open
Abstract
Three structural features of lipid A (addition of palmitate [C16 fatty acid], addition of aminoarabinose [positively charged amino sugar residue], and retention of 3-hydroxydecanoate [3-OH C10 fatty acid]) were determined for Pseudomonas aeruginosa isolates from patients with cystic fibrosis (CF; n=86), from the environment (n=13), and from patients with other conditions (n=14). Among P. aeruginosa CF isolates, 100% had lipid A with palmitate, 24.6% with aminoarabinose, and 33.3% retained 3-hydroxydecanoate. None of the isolates from the environment or from patients with other conditions displayed these modifications. These results indicate that unique lipid A modifications occur in clinical P. aeruginosa CF isolates.
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Affiliation(s)
- Robert K Ernst
- Department of Medicine, University of Washington, Seattle, WA 98195, USA.
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146
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Shaffer SA, Harvey MD, Goodlett DR, Ernst RK. Structural heterogeneity and environmentally regulated remodeling of Francisella tularensis subspecies novicida lipid A characterized by tandem mass spectrometry. J Am Soc Mass Spectrom 2007; 18:1080-92. [PMID: 17446084 PMCID: PMC2743246 DOI: 10.1016/j.jasms.2007.03.008] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2006] [Revised: 03/16/2007] [Accepted: 03/20/2007] [Indexed: 05/15/2023]
Abstract
The structural characterization of environmentally-regulated lipid A derived from Francisella tularensis subspecies novicida (Fn) U112 is described using negative electrospray ionization with a linear ion trap Fourier transform ion cyclotron resonance (IT-FT-ICR) hybrid mass spectrometer. The results indicate that a unique profile of lipid A molecular structures are synthesized in response to Fn growth at 25 degrees C versus 37 degrees C. Molecular species were found to be tetra-acylated, sharing a conserved glucosamine disaccharide backbone, a galactosamine-1-phosphate linked to the reducing glucosamine, and multiple O- and N-linked fatty acyl groups. Deprotonated molecules were interrogated by MS(n) scanning techniques at both high and nominal mass resolution and were found to be complex heterogeneous mixtures where structures differed based on the positions and identities of the O- and N-linked fatty acyl substituents. For the dominant ion series, which consisted of five peaks, 30 unique lipid A structures were identified. Estimates for the relative abundance of each structure were derived from MS relative abundance ratios and fragment ion ratios from comparable dissociation pathways from MS(2) through MS(4) experiments. The results suggest a remodeling pathway in which the amide linked fatty acid of the reducing glucosamine favors a 3-hydroxyhexadecanoic acid substituent for growth conditions at 25 degrees C versus a 3-hydroxyoctadecanoic acid substituent for growth conditions at 37 degrees C.
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Affiliation(s)
- Scott A Shaffer
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195, USA
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147
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D'Argenio DA, Wu M, Hoffman LR, Kulasekara HD, Déziel E, Smith EE, Nguyen H, Ernst RK, Larson Freeman TJ, Spencer DH, Brittnacher M, Hayden HS, Selgrade S, Klausen M, Goodlett DR, Burns JL, Ramsey BW, Miller SI. Growth phenotypes of Pseudomonas aeruginosa lasR mutants adapted to the airways of cystic fibrosis patients. Mol Microbiol 2007; 64:512-33. [PMID: 17493132 PMCID: PMC2742308 DOI: 10.1111/j.1365-2958.2007.05678.x] [Citation(s) in RCA: 267] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The opportunistic pathogen Pseudomonas aeruginosa undergoes genetic change during chronic airway infection of cystic fibrosis (CF) patients. One common change is a mutation inactivating lasR, which encodes a transcriptional regulator that responds to a homoserine lactone signal to activate expression of acute virulence factors. Colonies of lasR mutants visibly accumulated the iridescent intercellular signal 4-hydroxy-2-heptylquinoline. Using this colony phenotype, we identified P. aeruginosa lasR mutants that emerged in the airway of a CF patient early during chronic infection, and during growth in the laboratory on a rich medium. The lasR loss-of-function mutations in these strains conferred a growth advantage with particular carbon and nitrogen sources, including amino acids, in part due to increased expression of the catabolic pathway regulator CbrB. This growth phenotype could contribute to selection of lasR mutants both on rich medium and within the CF airway, supporting a key role for bacterial metabolic adaptation during chronic infection. Inactivation of lasR also resulted in increased beta-lactamase activity that increased tolerance to ceftazidime, a widely used beta-lactam antibiotic. Loss of LasR function may represent a marker of an early stage in chronic infection of the CF airway with clinical implications for antibiotic resistance and disease progression.
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Affiliation(s)
- David A D'Argenio
- Department of Microbiology, University of Washington, Seattle, WA, USA
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148
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Mohapatra NP, Soni S, Bell BL, Warren R, Ernst RK, Muszynski A, Carlson RW, Gunn JS. Identification of an orphan response regulator required for the virulence of Francisella spp. and transcription of pathogenicity island genes. Infect Immun 2007; 75:3305-14. [PMID: 17452468 PMCID: PMC1932945 DOI: 10.1128/iai.00351-07] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Francisella tularensis is a category A agent of biowarfare/biodefense. Little is known about the regulation of virulence gene expression in Francisella spp. Comparatively few regulatory factors exist in Francisella, including those belonging to two-component systems (TCS). However, orphan members of typical TCS can be identified. To determine if orphan TCS members affect Francisella gene expression, a gene encoding a product with high similarity to the Salmonella PmrA response regulator (FTT1557c/FNU0663.2) was deleted in Francisella novicida (a model organism for F. tularensis). The F. novicida pmrA mutant was defective in survival/growth within human and murine macrophage cell lines and was 100% defective in virulence in mice at a dose of up to 10(8) CFU. In addition, the mutant strain demonstrated increased susceptibility to antimicrobial peptide killing, but no differences were observed between the lipid A of the mutant and the parental strain, as has been observed with pmrA mutants of other microbes. The F. novicida pmrA mutant was 100% protective as a single-dose vaccine when challenge was with 10(6) CFU of F. novicida but did not protect against type A Schu S4 wild-type challenge. DNA microarray analysis identified 65 genes regulated by PmrA. The majority of these genes were located in the region surrounding pmrA or within the Francisella pathogenicity island (FPI). These FPI genes are also regulated by MglA, but MglA does not regulate pmrA, nor does PmrA regulate MglA. Thus, the orphan response regulator PmrA is an important factor in controlling virulence in F. novicida, and a pmrA mutant strain is an effective vaccine against homologous challenge.
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Affiliation(s)
- Nrusingh P Mohapatra
- Center for Microbial Interface Biology, Department of Molecular Biology, Immunology and Medical Genetics, The Ohio State University, 460 W. 12th Avenue, Columbus, OH 43210-1214, USA
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149
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Murray SR, Ernst RK, Bermudes D, Miller SI, Low KB. pmrA(Con) confers pmrHFIJKL-dependent EGTA and polymyxin resistance on msbB Salmonella by decorating lipid A with phosphoethanolamine. J Bacteriol 2007; 189:5161-9. [PMID: 17449614 PMCID: PMC1951887 DOI: 10.1128/jb.01969-06] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Mutations in pmrA were recombined into Salmonella strain ATCC 14028 msbB to determine if pmrA-regulated modifications of lipopolysaccharide could suppress msbB growth defects. A mutation that functions to constitutively activate pmrA [pmrA(Con)] suppresses msbB growth defects on EGTA-containing media. Lipid A structural analysis showed that Salmonella msbB pmrA(Con) strains, compared to Salmonella msbB strains, have increased amounts of palmitate and phosphoethanolamine but no aminoarabinose addition, suggesting that aminoarabinose is not incorporated into msbB lipid A. Surprisingly, loss-of-function mutations in the aminoarabinose biosynthetic genes restored EGTA and polymyxin sensitivity to Salmonella msbB pmrA(Con) strains. These blocks in aminoarabinose biosynthesis also prevented lipid A phosphoethanolamine incorporation and reduced the levels of palmitate addition, indicating previously unknown roles for the aminoarabinose biosynthetic enzymes. Lipid A structural analysis of the EGTA- and polymyxin-resistant triple mutant msbB pmrA(Con) pagP::Tn10, which contains phosphoethanolamine but no palmitoylated lipid A, suggests that phosphoethanolamine addition is sufficient to confer EGTA and polymyxin resistance on Salmonella msbB strains. Additionally, palmitoylated lipid A was observed only in wild-type Salmonella grown in the presence of salt in rich media. Thus, we correlate EGTA resistance and polymyxin resistance with phosphoethanolamine-decorated lipid A and demonstrate that the aminoarabinose biosynthetic proteins play an essential role in lipid A phosphoethanolamine addition and affect lipid A palmitate addition in Salmonella msbB strains.
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Affiliation(s)
- Sean R Murray
- Department of Biology, Yale University, New Haven, Connecticut, USA
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150
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Abstract
A key factor in the biology of Francisella spp. is lipopolysaccharide (LPS). Francisella LPS has many unique structural properties and poorly activates proinflammatory responses due to its lack of interaction with toll-like receptor 4 (TLR4). The LPS of this organism can be modified by various carbohydrates including glucose, mannose and galactosamine, which affect various aspects of virulence. Spontaneously occurring colony variants of F. tularensis have altered LPS. This altered LPS may account for the novel phenotypes of these variants that include effects on susceptibility to killing by normal human serum, intracellular survival and animal virulence. Mutants devoid of O-antigen (directed mutants in O-antigen biosynthetic genes) show reduced intracellular survival and mouse virulence. Thus, this surface component is important in F. tularensis pathogenesis, and the inability of the LPS to alarm the immune system coupled with its frequent modification/alteration likely aid the success of this pathogen during human infection.
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Affiliation(s)
- John S Gunn
- The Center for Microbial Interface Biology, The Ohio State University, Biomedical Research Tower, Rm. 1006, 460 W. 12th Ave., Columbus, OH 43210-1214, USA.
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