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Keltsch NG, Gazanis A, Dietrich C, Wick A, Heermann R, Tremel W, Ternes TA. Development of an analytical method to quantify N-acyl-homoserine lactones in bacterial cultures, river water, and treated wastewater. Anal Bioanal Chem 2024; 416:3555-3567. [PMID: 38703199 DOI: 10.1007/s00216-024-05306-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 03/15/2024] [Accepted: 04/11/2024] [Indexed: 05/06/2024]
Abstract
N-Acyl-homoserine lactones (AHL) play a major role in the communication of Gram-negative bacteria. They influence processes such as biofilm formation, swarming motility, and bioluminescence in the aquatic environment. A comprehensive analytical method was developed to elucidate the "chemical communication" in pure bacterial cultures as well as in the aquatic environment and engineered environments with biofilms. Due to the high diversity of AHLs and their low concentrations in water, a sensitive and selective LC-ESI-MS/MS method combined with solid-phase extraction was developed for 34 AHLs, optimized and validated to quantify AHLs in bacterial conditioned medium, river water, and treated wastewater. Furthermore, the developed method was optimized in terms of enrichment volume, internal standards, limits of detection, and limits of quantification in several matrices. An unanticipated variety of AHLs was detected in the culture media of Pseudomonas aeruginosa (in total 8 AHLs), Phaeobacter gallaeciensis (in total 6 AHLs), and Methylobacterium mesophilicum (in total 15 AHLs), which to our knowledge have not been described for these bacterial cultures so far. Furthermore, AHLs were detected in river water (in total 5 AHLs) and treated wastewater (in total 3 AHLs). Several detected AHLs were quantified (in total 24) using a standard addition method up to 7.3±1.0 µg/L 3-Oxo-C12-AHL (culture media of P. aeruginosa).
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Affiliation(s)
- N G Keltsch
- Bundesanstalt für Gewässerkunde, Am Mainzer Tor 1, Koblenz, 56068, Germany
- Universität Koblenz-Landau, Universitätsstraße 1, Koblenz, 56070, Germany
| | - A Gazanis
- Biozentrum II, Institut für Molekulare Physiologie, Mikrobiologie und Biotechnologie, Johannes Gutenberg-Universität Mainz, Hanns-Dieter-Hüsch-Weg 17, Mainz, 55128, Germany
| | - C Dietrich
- Bundesanstalt für Gewässerkunde, Am Mainzer Tor 1, Koblenz, 56068, Germany
| | - A Wick
- Bundesanstalt für Gewässerkunde, Am Mainzer Tor 1, Koblenz, 56068, Germany
| | - R Heermann
- Biozentrum II, Institut für Molekulare Physiologie, Mikrobiologie und Biotechnologie, Johannes Gutenberg-Universität Mainz, Hanns-Dieter-Hüsch-Weg 17, Mainz, 55128, Germany
| | - W Tremel
- Department of Chemistry, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, Mainz, 55099, Germany
| | - T A Ternes
- Bundesanstalt für Gewässerkunde, Am Mainzer Tor 1, Koblenz, 56068, Germany.
- Universität Koblenz-Landau, Universitätsstraße 1, Koblenz, 56070, Germany.
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2
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Tristán-Manzano M, Justicia-Lirio P, Maldonado-Pérez N, Cortijo-Gutiérrez M, Benabdellah K, Martin F. Externally-Controlled Systems for Immunotherapy: From Bench to Bedside. Front Immunol 2020; 11:2044. [PMID: 33013864 PMCID: PMC7498544 DOI: 10.3389/fimmu.2020.02044] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 07/28/2020] [Indexed: 12/27/2022] Open
Abstract
Immunotherapy is a very promising therapeutic approach against cancer that is particularly effective when combined with gene therapy. Immuno-gene therapy approaches have led to the approval of four advanced therapy medicinal products (ATMPs) for the treatment of p53-deficient tumors (Gendicine and Imlygic), refractory acute lymphoblastic leukemia (Kymriah) and large B-cell lymphomas (Yescarta). In spite of these remarkable successes, immunotherapy is still associated with severe side effects for CD19+ malignancies and is inefficient for solid tumors. Controlling transgene expression through an externally administered inductor is envisioned as a potent strategy to improve safety and efficacy of immunotherapy. The aim is to develop smart immunogene therapy-based-ATMPs, which can be controlled by the addition of innocuous drugs or agents, allowing the clinicians to manage the intensity and durability of the therapy. In the present manuscript, we will review the different inducible, versatile and externally controlled gene delivery systems that have been developed and their applications to the field of immunotherapy. We will highlight the advantages and disadvantages of each system and their potential applications in clinics.
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Affiliation(s)
- María Tristán-Manzano
- Gene and Cell Therapy Unit, Genomic Medicine Department, Pfizer-University of Granada-Junta de Andalucía Centre for Genomics and Oncological Research (GENYO), Granada, Spain
| | - Pedro Justicia-Lirio
- Gene and Cell Therapy Unit, Genomic Medicine Department, Pfizer-University of Granada-Junta de Andalucía Centre for Genomics and Oncological Research (GENYO), Granada, Spain.,LentiStem Biotech, Pfizer-University of Granada-Junta de Andalucía Centre for Genomics and Oncological Research (GENYO), Granada, Spain
| | - Noelia Maldonado-Pérez
- Gene and Cell Therapy Unit, Genomic Medicine Department, Pfizer-University of Granada-Junta de Andalucía Centre for Genomics and Oncological Research (GENYO), Granada, Spain
| | - Marina Cortijo-Gutiérrez
- Gene and Cell Therapy Unit, Genomic Medicine Department, Pfizer-University of Granada-Junta de Andalucía Centre for Genomics and Oncological Research (GENYO), Granada, Spain
| | - Karim Benabdellah
- Gene and Cell Therapy Unit, Genomic Medicine Department, Pfizer-University of Granada-Junta de Andalucía Centre for Genomics and Oncological Research (GENYO), Granada, Spain
| | - Francisco Martin
- Gene and Cell Therapy Unit, Genomic Medicine Department, Pfizer-University of Granada-Junta de Andalucía Centre for Genomics and Oncological Research (GENYO), Granada, Spain
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3
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Bloxham CJ, Foster SR, Thomas WG. A Bitter Taste in Your Heart. Front Physiol 2020; 11:431. [PMID: 32457649 PMCID: PMC7225360 DOI: 10.3389/fphys.2020.00431] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 04/08/2020] [Indexed: 12/11/2022] Open
Abstract
The human genome contains ∼29 bitter taste receptors (T2Rs), which are responsible for detecting thousands of bitter ligands, including toxic and aversive compounds. This sentinel function varies between individuals and is underpinned by naturally occurring T2R polymorphisms, which have also been associated with disease. Recent studies have reported the expression of T2Rs and their downstream signaling components within non-gustatory tissues, including the heart. Though the precise role of T2Rs in the heart remains unclear, evidence points toward a role in cardiac contractility and overall vascular tone. In this review, we summarize the extra-oral expression of T2Rs, focusing on evidence for expression in heart; we speculate on the range of potential ligands that may activate them; we define the possible signaling pathways they activate; and we argue that their discovery in heart predicts an, as yet, unappreciated cardiac physiology.
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Affiliation(s)
- Conor J Bloxham
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, St Lucia, QLD, Australia
| | - Simon R Foster
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Walter G Thomas
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, St Lucia, QLD, Australia
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Yadav VK, Singh PK, Sharma D, Singh SK, Agarwal V. Mechanism underlying N-(3-oxo-dodecanoyl)-L-homoserine lactone mediated intracellular calcium mobilization in human platelets. Blood Cells Mol Dis 2019; 79:102340. [PMID: 31207554 DOI: 10.1016/j.bcmd.2019.102340] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/19/2019] [Accepted: 05/19/2019] [Indexed: 10/26/2022]
Abstract
Acyl-homoserine lactones (AHLs), are the key autoinducer molecules that mediate Pseudomonas aeruginosa associated quorum sensing. P. aeruginosa produces two types of AHLs; N-(3-oxododecanoyl)-L-homoserine lactone (3-oxo-C12 HSL) and N-butyryl-L-homoserine lactone (C4 HSL). AHLs are not only regulating the virulence gene of bacteria but also influence the host cell functions by interkingdom signaling. In this study, we explored the mechanism of AHLs induced calcium mobilization in human platelets. We found that 3-oxo-C12 HSL but not C4 HSL induces intracellular calcium release. 3-oxo-C12 HSL induced calcium mobilization was majorly contributed from the dense tubular system (DTS). Furthermore, 3-oxo-C12 HSL also stimulates the store-operated Ca2+ entry (SOCE) in platelet. Intracellular calcium rise was significantly lowered in rotenone, and bafilomycin pre-treated platelets suggesting partial involvement of mitochondria and acidic vacuoles. The significant effect of 3-oxo-C12 HSL on calcium mobilization can alter the platelet functions that might results in thrombotic disorders in individuals infected with P. aeruginosa.
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Affiliation(s)
- Vivek Kumar Yadav
- Department of Biotechnology, Motilal Nehru National Institute of Technology Allahabad, Prayagraj, India
| | - Pradeep Kumar Singh
- Department of Biotechnology, Motilal Nehru National Institute of Technology Allahabad, Prayagraj, India
| | - Deepmala Sharma
- Department of Mathematics, National Institute of Technology, Raipur, India
| | - Sunil Kumar Singh
- Department of Animal Sciences, Central University of Punjab, Bathinda, India.
| | - Vishnu Agarwal
- Department of Biotechnology, Motilal Nehru National Institute of Technology Allahabad, Prayagraj, India.
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Hurley MN, Cámara M, Smyth AR. Novel approaches to the treatment of Pseudomonas aeruginosa infections in cystic fibrosis. Eur Respir J 2012; 40:1014-23. [PMID: 22743672 PMCID: PMC3461346 DOI: 10.1183/09031936.00042012] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Pseudomonas aeruginosa chronically infects patients with cystic fibrosis and is associated with greater morbidity. There has been limited progress on the clinical development of new antibiotics with novel modes of action. This review addresses some of the latest research developments on the exploitation of candidate adjuvant therapeutic agents that may act alongside conventional antibiotics as an alternative therapeutic strategy. After considering key mechanisms this opportunistic pathogen employs to control virulence, the progress of various strategies including the inhibition of quorum sensing, efflux pumps and lectins, and the use of iron chelators, bacteriophages, immunisation and immunotherapy is reviewed. Both therapeutic approaches in early development and clinical phase are discussed.
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Affiliation(s)
- Matthew N Hurley
- Dept of Child Health, University of Nottingham, E Floor, East Block, Queens Medical Centre, Nottingham, NG7 2UHUK.
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Fairchild KD, Srinivasan V, Moorman JR, Gaykema RPA, Goehler LE. Pathogen-induced heart rate changes associated with cholinergic nervous system activation. Am J Physiol Regul Integr Comp Physiol 2010; 300:R330-9. [PMID: 21068197 DOI: 10.1152/ajpregu.00487.2010] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The autonomic nervous system plays a central role in regulation of host defense and in physiological responses to sepsis, including changes in heart rate and heart rate variability. The cholinergic anti-inflammatory response, whereby infection triggers vagal efferent signals that dampen production of proinflammatory cytokines, would be predicted to result in increased vagal signaling to the heart and increased heart rate variability. In fact, decreased heart rate variability is widely described in humans with sepsis. Our studies elucidate this apparent paradox by showing that mice injected with pathogens demonstrate transient bradyarrhythmias of vagal origin in a background of decreased heart rate variability (HRV). Intraperitoneal injection of a large inoculum of Gram-positive or Gram-negative bacteria or Candida albicans rapidly induced bradyarrhythmias of sinus and AV nodal block, characteristic of cardiac vagal firing and dramatically increased short-term HRV. These pathogen-induced bradycardias were immediately terminated by atropine, an antagonist of muscarinic cholinergic receptors, demonstrating the role of vagal efferent signaling in this response. Vagal afferent signaling following pathogen injection was demonstrated by intense nuclear c-Fos activity in neurons of the vagal sensory ganglia and brain stem. Surprisingly, pathogen-induced bradycardia demonstrated rapid and prolonged desensitization and did not recur on repeat injection of the same organism 3 h or 3 days after the initial exposure. After recovery from the initial bradycardia, depressed heart rate variability developed in some mice and was correlated with elevated plasma cytokine levels and mortality. Our findings of decreased HRV and transient heart rate decelerations in infected mice are similar to heart rate changes described by our group in preterm neonates with sepsis. Pathogen sensing and signaling via the vagus nerve, and the desensitization of this response, may account for periods of both increased and decreased heart rate variability in sepsis.
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Affiliation(s)
- Karen D Fairchild
- Dept. of Pediatrics, University of Virginia Health System, Hospital Dr., Charlottesville, VA 22908, USA
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Davis BM, Jensen R, Williams P, O'Shea P. The interaction of N-acylhomoserine lactone quorum sensing signaling molecules with biological membranes: implications for inter-kingdom signaling. PLoS One 2010; 5:e13522. [PMID: 20975958 PMCID: PMC2958149 DOI: 10.1371/journal.pone.0013522] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Accepted: 09/24/2010] [Indexed: 01/28/2023] Open
Abstract
Background The long chain N-acylhomoserine lactone (AHL) quorum sensing signal molecules released by Pseudomonas aeruginosa have long been known to elicit immunomodulatory effects through a process termed inter-kingdom signaling. However, to date very little is known regarding the exact mechanism of action of these compounds on their eukaryotic targets. Methodology/Principal Findings The use of the membrane dipole fluorescent sensor di-8-ANEPPS to characterise the interactions of AHL quorum sensing signal molecules, N-(3-oxotetradecanoyl)-L-homoserine lactone (3-oxo-C14-HSL), N-(3-oxododecanoyl)homoserine-L-lactone (3-oxo-C12-HSL) and N-(3-oxodecanoyl) homoserine-L-lactone (3-oxo-C10 HSL) produced by Pseudomonas aeruginosa with model and cellular membranes is reported. The interactions of these AHLs with artificial membranes reveal that each of the compounds is capable of membrane interaction in the micromolar concentration range causing significant modulation of the membrane dipole potential. These interactions fit simple hyperbolic binding models with membrane affinity increasing with acyl chain length. Similar results were obtained with T-lymphocytes providing the evidence that AHLs are capable of direct interaction with the plasma membrane. 3-oxo-C12-HSL interacts with lymphocytes via a cooperative binding model therefore implying the existence of an AHL membrane receptor. The role of cholesterol in the interactions of AHLs with membranes, the significance of modulating cellular dipole potential for receptor conformation and the implications for immune modulation are discussed. Conclusions/ Significance Our observations support previous findings that increasing AHL lipophilicity increases the immunomodulatory activity of these quorum compounds, while providing evidence to suggest membrane interaction plays an important role in quorum sensing and implies a role for membrane microdomains in this process. Finally, our results suggest the existence of a eukaryotic membrane-located system that acts as an AHL receptor.
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Affiliation(s)
- Benjamin Michael Davis
- Cell Biophysics Group, Institute of Biophysics, Imaging and Optical Science, University of Nottingham, Nottingham, United Kingdom
| | - Rasmus Jensen
- School of Molecular Medical Sciences, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Paul Williams
- School of Molecular Medical Sciences, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Paul O'Shea
- Cell Biophysics Group, Institute of Biophysics, Imaging and Optical Science, University of Nottingham, Nottingham, United Kingdom
- * E-mail:
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8
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Atkinson S, Williams P. Quorum sensing and social networking in the microbial world. J R Soc Interface 2009; 6:959-78. [PMID: 19674996 PMCID: PMC2827448 DOI: 10.1098/rsif.2009.0203] [Citation(s) in RCA: 247] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Accepted: 07/10/2009] [Indexed: 12/15/2022] Open
Abstract
For many years, bacterial cells were considered primarily as selfish individuals, but, in recent years, it has become evident that, far from operating in isolation, they coordinate collective behaviour in response to environmental challenges using sophisticated intercellular communication networks. Cell-to-cell communication between bacteria is mediated by small diffusible signal molecules that trigger changes in gene expression in response to fluctuations in population density. This process, generally referred to as quorum sensing (QS), controls diverse phenotypes in numerous Gram-positive and Gram-negative bacteria. Recent advances have revealed that bacteria are not limited to communication within their own species but are capable of 'listening in' and 'broadcasting to' unrelated species to intercept messages and coerce cohabitants into behavioural modifications, either for the good of the population or for the benefit of one species over another. It is also evident that QS is not limited to the bacterial kingdom. The study of two-way intercellular signalling networks between bacteria and both uni- and multicellular eukaryotes as well as between eukaryotes is just beginning to unveil a rich diversity of communication pathways.
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Affiliation(s)
- Steve Atkinson
- Centre for Biomolecular Sciences, School of Molecular Medical Sciences, University of Nottingham, Nottingham NG7 2RD, UK.
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Sbarbati A, Merigo F, Osculati F. Eukaryotic vs. prokaryotic chemosensory systems. Biomed Pharmacother 2009; 64:233-9. [PMID: 20347567 DOI: 10.1016/j.biopha.2009.06.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2009] [Accepted: 06/07/2009] [Indexed: 01/10/2023] Open
Abstract
In the last decades, microbiologists demonstrated that microorganisms possess chemosensory capabilities and communicate with each other via chemical signals. In parallel, it was demonstrated that solitary eukaryotic chemosensory cells are diffusely located on the mucosae of digestive and respiratory apparatuses. It is now evident that on the mucosal surfaces of vertebrates, two chemoreceptorial systems (i.e. eukaryotic and prokaryotic) coexist in a common microenvironment. To date, it is not known if the two chemosensory systems reciprocally interact and compete for detection of chemical cues. This appears to be a fruitful field of study and future researches must consider that the mucosal epithelia possess more chemosensory capabilities than previously supposed.
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Affiliation(s)
- Andrea Sbarbati
- Dipartimento di Scienze Morfologico-Biomediche, Sezione di Anatomia ed Istologia, Università di Verona, Strada Le Grazie 8, 37134, Verona, Italy.
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10
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Williams P, Cámara M. Quorum sensing and environmental adaptation in Pseudomonas aeruginosa: a tale of regulatory networks and multifunctional signal molecules. Curr Opin Microbiol 2009; 12:182-91. [PMID: 19249239 DOI: 10.1016/j.mib.2009.01.005] [Citation(s) in RCA: 533] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2009] [Revised: 01/19/2009] [Accepted: 01/22/2009] [Indexed: 11/24/2022]
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Tait K, Williamson H, Atkinson S, Williams P, Cámara M, Joint I. Turnover of quorum sensing signal molecules modulates cross-kingdom signalling. Environ Microbiol 2009; 11:1792-802. [PMID: 19508552 DOI: 10.1111/j.1462-2920.2009.01904.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
N-acylhomoserine lactone (AHL) quorum-sensing molecules modulate the swimming behaviour of zoospores of the macroalga Ulva to facilitate the location of bacterial biofilms. Here we show that the intertidal surfaces colonized by Ulva are dominated by Alphaproteobacteria, particularly the Rhodobacteraceae family, and the Bacteroidetes family Flavobacteriaceae, and that this diverse assemblage both produces and degrades AHLs. N-acylhomoserine lactones could also be extracted from the surfaces of pebbles recovered from intertidal rock-pools. Bacteria representative of this assemblage were isolated and tested for the production and degradation of AHLs, and for their ability to modulate zoospore settlement at different biofilm densities. Of particular interest was a Shewanella sp. This strain produced three major AHLs (OC4, OC10 and OC12) in the late exponential phase, but the longer-chain AHLs were rapidly degraded in the stationary phase. Degradation occurred via both lactonase and amidase activity. A close relationship was found between AHL synthesis and Ulva zoospore settlement. The Shewanella isolate also interfered with AHL production by a Sulfitobacter isolate and its ability to enhance zoospore settlement in a polymicrobial biofilm. This influence on the attachment of Ulva zoospores suggests that AHL-degrading strains can affect bacterial community behaviour by interfering with quorum sensing between neighbouring bacteria. More importantly, these interactions may exert wider ecological effects across different kingdoms.
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Affiliation(s)
- Karen Tait
- Plymouth Marine Laboratory, Prospect Place, Plymouth, PL1 3DH, UK.
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Sbarbati A, Tizzano M, Merigo F, Benati D, Nicolato E, Boschi F, Cecchini MP, Scambi I, Osculati F. Acyl Homoserine Lactones Induce Early Response in the Airway. Anat Rec (Hoboken) 2009; 292:439-48. [DOI: 10.1002/ar.20866] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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13
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Pearman WF, Lawrence-Snyder M, Angel SM, Decho AW. Surface-enhanced Raman spectroscopy for in situ measurements of signaling molecules (autoinducers) relevant to bacteria quorum sensing. APPLIED SPECTROSCOPY 2007; 61:1295-1300. [PMID: 18198020 DOI: 10.1366/000370207783292244] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Autoinducer (AI) molecules are used by quorum sensing (QS) bacteria to communicate information about their environment and are critical to their ability to coordinate certain physiological activities. Studying how these organisms react to environmental stresses could provide insight into methods to control these activities. To this end, we are investigating spectroscopic methods of analysis that allow in situ measurements of these AI molecules under different environmental conditions. We found that for one class of AIs, N-acyl-homoserine lactones (AHLs), surface-enhanced Raman spectroscopy (SERS) is a method capable of performing such measurements in situ. SERS spectra of seven different AHLs with acyl chain lengths from 4 to 12 carbons were collected for the first time using Ag colloidal nanoparticles synthesized via both citrate and borohydride reduction methods. Strong SERS spectra were obtained in as little as 10 seconds for 80 microM solutions of AI that exhibited the strongest SERS response, whereas 20 seconds was typical for most AI SERS spectra collected during this study. Although all spectra were similar, significant differences were detected in the SERS spectra of C4-AHL and 3-oxo-C6-AHL and more subtle differences were noted between all AHLs. Initial results indicate a detection limit of approximately 10(-6)M for C6-AHL, which is within the limits of biologically relevant concentrations of AI molecules (nM-microM). Based on these results, the SERS method shows promise for monitoring AI molecule concentrations in situ, within biofilms containing QS bacteria. This new capability offers the possibility to "listen in" on chemical communications between bacteria in their natural environment as that environment is stressed.
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Affiliation(s)
- William F Pearman
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
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14
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Williams P. Quorum sensing, communication and cross-kingdom signalling in the bacterial world. Microbiology (Reading) 2007; 153:3923-3938. [DOI: 10.1099/mic.0.2007/012856-0] [Citation(s) in RCA: 500] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Affiliation(s)
- Paul Williams
- Institute of Infection, Immunity and Inflammation, Centre for Biomolecular Sciences, University of Nottingham, Nottingham NG7 2RD, UK
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15
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Williams P, Winzer K, Chan WC, Cámara M. Look who's talking: communication and quorum sensing in the bacterial world. Philos Trans R Soc Lond B Biol Sci 2007; 362:1119-34. [PMID: 17360280 PMCID: PMC2435577 DOI: 10.1098/rstb.2007.2039] [Citation(s) in RCA: 493] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
For many years bacteria were considered primarily as autonomous unicellular organisms with little capacity for collective behaviour. However, we now appreciate that bacterial cells are in fact, highly communicative. The generic term 'quorum sensing' has been adopted to describe the bacterial cell-to-cell communication mechanisms which co-ordinate gene expression usually, but not always, when the population has reached a high cell density. Quorum sensing depends on the synthesis of small molecules (often referred to as pheromones or autoinducers) that diffuse in and out of bacterial cells. As the bacterial population density increases, so does the synthesis of quorum sensing signal molecules, and consequently, their concentration in the external environment rises. Once a critical threshold concentration has been reached, a target sensor kinase or response regulator is activated (or repressed) so facilitating the expression of quorum sensing-dependent genes. Quorum sensing enables a bacterial population to mount a co-operative response that improves access to nutrients or specific environmental niches, promotes collective defence against other competitor prokaryotes or eukaryotic defence mechanisms and facilitates survival through differentiation into morphological forms better able to combat environmental threats. Quorum sensing also crosses the prokaryotic-eukaryotic boundary since quorum sensing-dependent signalling can be exploited or inactivated by both plants and mammals.
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Affiliation(s)
- Paul Williams
- Institute of Infection, Immunity and Inflammation, Centre for Biomolecular Sciences, School of Molecular Medical Sciences, University of Nottingham, Nottingham NG7 2RD, UK.
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16
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Sbarbati A, Osculati F. Allelochemical Communication in Vertebrates: Kairomones, Allomones and Synomones. Cells Tissues Organs 2006; 183:206-19. [PMID: 17159346 DOI: 10.1159/000096511] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2006] [Indexed: 12/22/2022] Open
Abstract
Communication between different species by means of chemicals (allelomones) is widespread among prokaryotes, plants and invertebrates. This study reviews data suggesting that allelochemically mediated communication also exists among vertebrates. The work aims to provide a concise, interdisciplinary review of communication mediated by infochemicals, with a focus on interspecies and interkingdom signaling. A definition of infochemicals is given, with a brief review of the general principles of chemical communication in different kingdoms in nature. Findings are reported which suggest that interspecies chemical signaling is important for vertebrates also. It is proposed that the general laws of chemical ecology are valid for mammals too, and that the terms indicating the different types of allelomones (i.e. kairomone, allomone and synomone) might also be used in medicine. In particular, the microchemical environment at the airway and digestive interfaces are discussed from an infochemical point of view.
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Affiliation(s)
- A Sbarbati
- Department of Morphological-Biomedical Sciences, Section of Anatomy and Histology, University of Verona, Verona, Italy.
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17
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Shiner EK, Terentyev D, Bryan A, Sennoune S, Martinez-Zaguilan R, Li G, Gyorke S, Williams SC, Rumbaugh KP. Pseudomonas aeruginosa autoinducer modulates host cell responses through calcium signalling. Cell Microbiol 2006; 8:1601-10. [PMID: 16984415 DOI: 10.1111/j.1462-5822.2006.00734.x] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The opportunistic pathogen Pseudomonas aeruginosa utilizes a cell density-dependent signalling phenomenon known as quorum sensing (QS) to regulate several virulence factors needed for infection. Acylated homoserine lactones, or autoinducers, are the primary signal molecules that mediate QS in P. aeruginosa. The autoinducer N-3O-dodecanoyl-homoserine lactone (3O-C12) exerts effects on mammalian cells, including upregulation of pro-inflammatory mediators and induction of apoptosis. However, the mechanism(s) by which 3O-C12 affects mammalian cell responses is unknown. Here we report that 3O-C12 induces apoptosis and modulates the expression of immune mediators in murine fibroblasts and human vascular endothelial cells (HUVEC). The effects of 3O-C12 were accompanied by increases in cytosolic calcium levels that were mobilized from intracellular stores in the endoplasmic reticulum (ER). Calcium release was blocked by an inhibitor of phospholipase C, suggesting that release occurred through inositol triphosphate (IP3) receptors in the ER. Apoptosis, but not immunodulatory gene activation, was blocked when 3O-C12-exposed cells were co-incubated with inhibitors of calcium signalling. This study indicates that 3O-C12 can activate at least two independent signal transduction pathways in mammalian cells, one that involves increases in intracellular calcium levels and leads to apoptosis, and a second pathway that results in modulation of the inflammatory response.
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Affiliation(s)
- E K Shiner
- Department of Microbiology and Immunology, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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18
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Qazi S, Middleton B, Muharram SH, Cockayne A, Hill P, O'Shea P, Chhabra SR, Cámara M, Williams P. N-acylhomoserine lactones antagonize virulence gene expression and quorum sensing in Staphylococcus aureus. Infect Immun 2006; 74:910-9. [PMID: 16428734 PMCID: PMC1360299 DOI: 10.1128/iai.74.2.910-919.2006] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Many gram-negative bacteria employ N-acylhomoserine lactone (AHL)-mediated quorum sensing to control virulence. To determine whether gram-positive bacteria such as Staphylococcus aureus respond to AHLs, we used a growth-dependent lux reporter fusion. Exposure of S. aureus to different AHLs revealed that 3-oxo-substituted AHLs with C10 to C14 acyl chains inhibited light output and growth in a concentration-dependent manner, while short-chain AHLs had no effect. N-(3-Oxododecanoyl)-L-homoserine lactone (3-oxo-C12-HSL) inhibited the production of exotoxins and cell wall fibronectin-binding proteins but enhanced protein A expression. Since these processes are reciprocally regulated via the S. aureus agr quorum-sensing system, which in turn, is regulated via sar, we examined the effect of AHLs on sarA and agr. At sub-growth-inhibitory concentrations of 3-oxo-C12-HSL, both sarA expression and agr expression were inhibited, indicating that the action of 3-oxo-C12-HSL is mediated at least in part through antagonism of quorum sensing in S. aureus. Spent culture supernatants from Pseudomonas aeruginosa, which produces both 3-oxo-C12-HSL and N-butanoyl-homoserine lactone (C4-HSL), also inhibited agr expression, although C4-HSL itself was inactive in this assay. Since quorum sensing in S. aureus depends on the activities of membrane-associated proteins, such as AgrB, AgrC, and AgrD, we investigated whether AHLs perturbed S. aureus membrane functionality by determining their influence on the membrane dipole potential. From the binding curves obtained, a dissociation constant of 7 muM was obtained for 3-oxo-C12-HSL, indicating the presence of a specific saturable receptor, whereas no binding was observed for C4-HSL. These data demonstrate that long-chain 3-oxo-substituted AHLs, such as 3-oxo-C12-HSL, are capable of interacting with the S. aureus cytoplasmic membrane in a saturable, specific manner and at sub-growth-inhibitory concentrations, down-regulating exotoxin production and both sarA and agr expression.
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Affiliation(s)
- Saara Qazi
- Institute of Infection, Immunity and Inflammation, Centre for Biomolecular Sciences, University of Nottingham, Nottingham NG7 2RD, United Kingdom
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19
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Atkinson S, Chang CY, Sockett RE, Cámara M, Williams P. Quorum sensing in Yersinia enterocolitica controls swimming and swarming motility. J Bacteriol 2006; 188:1451-61. [PMID: 16452428 PMCID: PMC1367215 DOI: 10.1128/jb.188.4.1451-1461.2006] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2005] [Accepted: 11/22/2005] [Indexed: 11/20/2022] Open
Abstract
The Yersinia enterocolitica LuxI homologue YenI directs the synthesis of N-3-(oxohexanoyl)homoserine lactone (3-oxo-C6-HSL) and N-hexanoylhomoserine lactone (C6-HSL). In a Y. enterocolitica yenI mutant, swimming motility is temporally delayed while swarming motility is abolished. Since both swimming and swarming are flagellum dependent, we purified the flagellin protein from the parent and yenI mutant. Electrophoresis revealed that in contrast to the parent strain, the yenI mutant grown for 17 h at 26 degrees C lacked the 45-kDa flagellin protein FleB. Reverse transcription-PCR indicated that while mutation of yenI had no effect on yenR, flhDC (the motility master regulator) or fliA (the flagellar sigma factor) expression, fleB (the flagellin structural gene) was down-regulated. Since 3-oxo-C6-HSL and C6-HSL did not restore swimming or swarming in the yenI mutant, we reexamined the N-acylhomoserine lactone (AHL) profile of Y. enterocolitica. Using AHL biosensors and mass spectrometry, we identified three additional AHLs synthesized via YenI: N-(3-oxodecanoyl)homoserine lactone, N-(3-oxododecanoyl)homoserine lactone (3-oxo-C12-HSL), and N-(3-oxotetradecanoyl)homoserine lactone. However, none of the long-chain AHLs either alone or in combination with the short-chain AHLs restored swarming or swimming in the yenI mutant. By investigating the transport of radiolabeled 3-oxo-C12-HSL and by introducing an AHL biosensor into the yenI mutant we demonstrate that the inability of exogenous AHLs to restore motility to the yenI mutant is not related to a lack of AHL uptake. However, both AHL synthesis and motility were restored by complementation of the yenI mutant with a plasmid-borne copy of yenI.
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Affiliation(s)
- Steve Atkinson
- Institute of Infections, Immunity and Inflammation, Centre for Biomolecular Science, University of Nottingham, Nottingham NG7 2RD, United Kingdom.
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20
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Uroz S, Chhabra SR, Cámara M, Williams P, Oger P, Dessaux Y. N-Acylhomoserine lactone quorum-sensing molecules are modified and degraded by Rhodococcus erythropolis W2 by both amidolytic and novel oxidoreductase activities. Microbiology (Reading) 2005; 151:3313-3322. [PMID: 16207914 DOI: 10.1099/mic.0.27961-0] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Rhodococcus erythropolis strain W2 has been shown previously to degrade the N-acylhomoserine lactone (AHL) quorum-sensing signal molecule N-hexanoyl-l-homoserine lactone, produced by other bacteria. Data presented here indicate that this Gram-positive bacterium is also capable of using various AHLs as the sole carbon and energy source. The enzymic activities responsible for AHL inactivation were investigated in R. erythropolis cell extracts and in whole cells. R. erythropolis cells rapidly degraded AHLs with 3-oxo substituents but exhibited relatively poor activity against the corresponding unsubstituted AHLs. Investigation of the mechanism(s) by which R. erythropolis cells degraded AHLs revealed that 3-oxo compounds with N-acyl side chains ranging from C8 to C14 were initially converted to their corresponding 3-hydroxy derivatives. This oxidoreductase activity was not specific to 3-oxo-AHLs but also allowed the reduction of compounds such as N-(3-oxo-6-phenylhexanoyl)homoserine lactone (which contains an aromatic acyl chain substituent) and 3-oxododecanamide (which lacks the homoserine lactone ring). It also reduced both the d- and l-isomers of n-(3-oxododecanoyl)-l-homoserine lactone. A second AHL-degrading activity was observed when R. erythropolis cell extracts were incubated with N-(3-oxodecanoyl)-l-homoserine lactone (3O,C10-HSL). This activity was both temperature- and pH-dependent and was characterized as an amidolytic activity by HPLC analysis of the reaction mixture treated with dansyl chloride. This revealed the accumulation of dansylated homoserine lactone, indicating that the 3O,C10-HSL amide had been cleaved to yield homoserine lactone. R. erythropolis is therefore capable of modifying and degrading AHL signal molecules through both oxidoreductase and amidolytic activities.
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Affiliation(s)
- Stéphane Uroz
- Interactions Plantes et Micro-organismes de la Rhizosphère, Institut des Sciences du Végétal, CNRS, Bâtiment 23, Avenue de la Terrasse, 91198 Gif-sur-Yvette CEDEX, France
| | - Siri Ram Chhabra
- Institute of Infection, Immunity and Inflammation, Centre for Biomolecular Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - Miguel Cámara
- Institute of Infection, Immunity and Inflammation, Centre for Biomolecular Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - Paul Williams
- Institute of Infection, Immunity and Inflammation, Centre for Biomolecular Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - Phil Oger
- Laboratoire des Sciences de la Terre, École Normale Supérieure de Lyon, 43 Allée D'Italie, 69364 Lyon CEDEX 07, France
| | - Yves Dessaux
- Interactions Plantes et Micro-organismes de la Rhizosphère, Institut des Sciences du Végétal, CNRS, Bâtiment 23, Avenue de la Terrasse, 91198 Gif-sur-Yvette CEDEX, France
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21
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Tait K, Joint I, Daykin M, Milton DL, Williams P, Cámara M. Disruption of quorum sensing in seawater abolishes attraction of zoospores of the green alga Ulva to bacterial biofilms. Environ Microbiol 2005; 7:229-40. [PMID: 15658990 DOI: 10.1111/j.1462-2920.2004.00706.x] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Zoospores of the eukaryotic green seaweed Ulva respond to bacterial N-acylhomoserine lactone (AHL) quorum sensing signal molecules for the selection of surface sites for permanent attachment. In this study we have investigated the production and destruction of AHLs in biofilms of the AHL-producing marine bacterium, Vibrio anguillarum and their stability in seawater. While wild type V. anguillarum NB10 was a strong attractor of zoospores, inactivation of AHL production in this strain by either expressing the recombinant Bacillus lactonase coding gene aiiA, or by mutating the AHL biosynthetic genes, resulted in the abolition of zoospore attraction. In seawater, with a pH of 8.2, the degradation of AHL molecules was temperature-dependent, indicating that the AHLs produced by marine bacterial biofilms have short half-lives. The Ulva zoospores sensed a range of different AHL molecules and in particular more zoospores settled on surfaces releasing AHLs with longer (>six carbons) N-linked acyl chains. However, this finding is likely to be influenced by the differential diffusion rates of AHLs from the experimental surface matrix. Molecules with longer N-acyl chains, such as N-(3-oxodecanoyl)- L-homoserine lactone, diffused more slowly than those with shorter N-acyl chains such as N-(3-hydroxy-hexanoyl)- L-homoserine lactone. Image analysis using GFP-tagged V. anguillarum biofilms revealed that spores settle directly on bacterial cells and in particular on microcolonies which we show are sites of concentrated AHL production.
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Affiliation(s)
- Karen Tait
- Plymouth Marine Laboratory, Prospect Place, Plymouth, PL1 3DH, UK.
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22
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Ritchie AJ, Jansson A, Stallberg J, Nilsson P, Lysaght P, Cooley MA. The Pseudomonas aeruginosa quorum-sensing molecule N-3-(oxododecanoyl)-L-homoserine lactone inhibits T-cell differentiation and cytokine production by a mechanism involving an early step in T-cell activation. Infect Immun 2005; 73:1648-55. [PMID: 15731065 PMCID: PMC1064928 DOI: 10.1128/iai.73.3.1648-1655.2005] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The Pseudomonas aeruginosa quorum-sensing molecule N-3-(oxododecanoyl)-L-homoserine lactone (OdDHL) has been reported to have immunomodulatory activity in several systems, although the mechanism of that activity remains to be fully characterized. We demonstrate here, using a defined in vitro model of antigen responses by T-cell receptor (TCR)-transgenic mouse splenic CD4 T cells, that the effect of OdDHL on activation and cytokine production is complete within 4 h of antigen or mitogen stimulation and does not depend on the insertion of OdDHL in the cell membrane, despite a previous report that immunosuppression by homoserine lactones required a minimum acyl chain length of 11 carbons (S. R. Chhabra, C. Harty, D. S. W. Hooi, M. Daykin, B. W. Bycroft, P. Williams, and D. Pritchard, J. Med. Chem. 46:97-104, 2003). We also demonstrate that while OdDHL can have toxic effects on nonlymphoid leukocytes, it does not induce significant cell death in T cells at the concentrations (< or =10 microM) used in these experiments. In addition, we show that primary and secondary antigen-specific cytokine responses are equally susceptible to inhibition by OdDHL and that the compound inhibits the differentiation of both Th1 and Th2 cells. However, the precise balance of cytokine production by CD4 T cells stimulated in the presence of OdDHL varies with both the antigen concentration and its affinity for the transgenic TCR. Thus, conflicting reports of the nature of the immunosuppression by OdDHL may be due in part to the differences in antigen affinity and concentration in different models.
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Affiliation(s)
- A J Ritchie
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
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23
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Bauer WD, Mathesius U. Plant responses to bacterial quorum sensing signals. CURRENT OPINION IN PLANT BIOLOGY 2004; 7:429-33. [PMID: 15231266 DOI: 10.1016/j.pbi.2004.05.008] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Bacterial infection of plants often depends on the exchange of quorum sensing signals between nearby bacterial cells. It is now evident that plants, in turn, 'listen' to these bacterial signals and respond in sophisticated ways to the information. Plants also secrete compounds that mimic the bacterial signals and thereby confuse quorum sensing regulation in bacteria.
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Affiliation(s)
- Wolfgang D Bauer
- Horticulture and Crop Science, 2021 Coffey Road, Ohio State University, Columbus, Ohio 43210, USA.
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24
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Ritchie AJ, Yam AOW, Tanabe KM, Rice SA, Cooley MA. Modification of in vivo and in vitro T- and B-cell-mediated immune responses by the Pseudomonas aeruginosa quorum-sensing molecule N-(3-oxododecanoyl)-L-homoserine lactone. Infect Immun 2003; 71:4421-31. [PMID: 12874321 PMCID: PMC165988 DOI: 10.1128/iai.71.8.4421-4431.2003] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
N-3-(oxododecanoyl)-L-homoserine lactone (OdDHL), a quorum-sensing molecule of Pseudomonas aeruginosa, plays an important role in the pathogenesis of the organism through its control of virulence factor expression. Several reports have suggested that OdDHL can also directly modulate host immune responses. However, the nature of the modulation is controversial, with different reports suggesting promotion of either humoral (Th2-mediated) or inflammatory (Th1-mediated) responses. This report describes a series of studies which demonstrate for the first time that in vivo administration of OdDHL can modulate the course of an antibody response, with an increase in ovalbumin (OVA)-specific immunogloblulin G1 (IgG1) but not IgG2a in OdDHL-treated OVA-immunized BALB/c mice compared to levels for controls. In vitro stimulation of lymphocytes from both Th1-biased C57Bl/6 and T-cell receptor transgenic mice and Th2-biased BALB/c mice in the presence of OdDHL demonstrated that OdDHL inhibits in vitro cytokine production in response to both mitogen and antigen, with gamma interferon (IFN-gamma) tending to be more inhibited than interleukin-4 (IL-4). In vitro mitogen or antigen restimulation of cells from mice treated with OdDHL in vivo shows effects on cytokine production which depend on the underlying immune bias of the mouse strain used, with a relative increase of IFN-gamma in Th1-biased C57Bl/6 mice and a relative increase of IL-4 in Th2-biased BALB/c mice. Thus, the mode of action of OdDHL on T-cell cytokine production is likely to be a relatively nonspecific one which accentuates an underlying immune response bias rather than one which specifically targets either Th1 or Th2 responses.
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Affiliation(s)
- Adam J Ritchie
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, New South Wales, Australia 2052
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25
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Neddermann P, Gargioli C, Muraglia E, Sambucini S, Bonelli F, De Francesco R, Cortese R. A novel, inducible, eukaryotic gene expression system based on the quorum-sensing transcription factor TraR. EMBO Rep 2003; 4:159-65. [PMID: 12612605 PMCID: PMC1315832 DOI: 10.1038/sj.embor.embor734] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2002] [Revised: 11/14/2002] [Accepted: 11/28/2002] [Indexed: 11/09/2022] Open
Abstract
Bacteria adapt their pattern of gene expression in response to a variety of external cues, including fluctuations in population density. This type of bacterial cell-to-cell communication is referred to as quorum-sensing. Quorum-sensing systems are present in many bacterial species and constitute a large collection of ligands and cognate receptors. The availability of such diversity offers interesting opportunities for biotechnological exploitation. We describe here the transformation of the quorum-sensing system of Agrobacterium tumefaciens into a transcription regulatory system that works in mammalian cells. The A. tumefaciens TraR protein was fused to the eukaryotic activation domain of NF-kappaB p65, generating a novel chimaeric transcriptional activator that stimulates gene transcription in different human cell lines from a minimal promoter containing the TraR DNA recognition sequence in the presence of the Agrobacterium quorum-sensing signal molecule N-(3-oxo-octanoyl)homoserine lactone (3-oxo-C(8)-HSL). The basal level of transcription was low in the absence of 3-oxo-C(8)-HSL, and gene expression was stimulated up to 1,000-fold at a saturating concentration of 3-oxo-C(8)-HSL.
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Affiliation(s)
- Petra Neddermann
- Istituto di Ricerche di Biologia Molecolare P. Angeletti, Via Pontina Km 30.600, 00040 Pomezia/Roma, Italy.
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26
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Cámara M, Williams P, Hardman A. Controlling infection by tuning in and turning down the volume of bacterial small-talk. THE LANCET. INFECTIOUS DISEASES 2002; 2:667-76. [PMID: 12409047 DOI: 10.1016/s1473-3099(02)00447-4] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
As the prevalence of bacterial resistance to multiple antibiotics increases it is becoming progressively more difficult to treat infections and, in many cases, the available therapeutic options are severely limited. Hence, there is a growing urgency to the search for novel targets and the development of new antimicrobials. To infect a host and cause disease bacteria produce an array of virulence determinants that contribute to pathogenesis. It is now known that many different Gram-positive and Gram-negative pathogens communicate via the production and sensing of small, diffusible signal molecules, to coordinate virulence determinant production. As a consequence, this event, now termed quorum sensing, represents a novel therapeutic target offering the opportunity to attenuate virulence, and thus control infection, by blocking cell-to-cell communication.
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Affiliation(s)
- Miguel Cámara
- School of Pharmaceutical Sciences, University of Nottingham, Nottingham, UK
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27
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Yates EA, Philipp B, Buckley C, Atkinson S, Chhabra SR, Sockett RE, Goldner M, Dessaux Y, Cámara M, Smith H, Williams P. N-acylhomoserine lactones undergo lactonolysis in a pH-, temperature-, and acyl chain length-dependent manner during growth of Yersinia pseudotuberculosis and Pseudomonas aeruginosa. Infect Immun 2002; 70:5635-46. [PMID: 12228292 PMCID: PMC128322 DOI: 10.1128/iai.70.10.5635-5646.2002] [Citation(s) in RCA: 421] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In gram-negative bacterial pathogens, such as Pseudomonas aeruginosa and Yersinia pseudotuberculosis, cell-to-cell communication via the N-acylhomoserine lactone (AHL) signal molecules is involved in the cell population density-dependent control of genes associated with virulence. This phenomenon, termed quorum sensing, relies upon the accumulation of AHLs to a threshold concentration at which target structural genes are activated. By using biosensors capable of detecting a range of AHLs we observed that, in cultures of Y. pseudotuberculosis and P. aeruginosa, AHLs accumulate during the exponential phase but largely disappear during the stationary phase. When added to late-stationary-phase, cell-free culture supernatants of the respective pathogen, the major P. aeruginosa [N-butanoylhomoserine lactone (C4-HSL) and N-(3-oxododecanoyl)homoserine lactone (3-oxo-C12-HSL)] and Y. pseudotuberculosis [N-(3-oxohexanoyl)homoserine lactone (3-oxo-C6-HSL) and N-hexanoylhomoserine lactone (C6-HSL)] AHLs were inactivated. Short-acyl-chain compounds (e.g., C4-HSL) were turned over more extensively than long-chain molecules (e.g., 3-oxo-C12-HSL). Little AHL inactivation occurred with cell extracts, and no evidence for inactivation by specific enzymes was apparent. This AHL turnover was discovered to be due to pH-dependent lactonolysis. By acidifying the growth media to pH 2.0, lactonolysis could be reversed. By using carbon-13 nuclear magnetic resonance spectroscopy, we found that the ring opening of homoserine lactone (HSL), N-propionyl HSL (C3-HSL), and C4-HSL increased as pH increased but diminished as the N-acyl chain was lengthened. At low pH levels, the lactone rings closed but not via a simple reversal of the ring opening reaction mechanism. Ring opening of C4-HSL, C6-HSL, 3-oxo-C6-HSL, and N-octanoylhomoserine lactone (C8-HSL), as determined by the reduction of pH in aqueous solutions with time, was also less rapid for AHLs with more electron-donating longer side chains. Raising the temperature from 22 to 37 degrees C increased the rate of ring opening. Taken together, these data show that (i) to be functional under physiological conditions in mammalian tissue fluids, AHLs require an N-acyl side chain of at least four carbons in length and (ii) that the longer the acyl side chain the more stable the AHL signal molecule.
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Affiliation(s)
- Edwin A Yates
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
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28
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Abstract
The emergence of bacterial strains exhibiting resistance to multiple antibiotic classes poses a major threat to medicine and public health. This has been compounded over the last few decades by the failure of drug discovery programmes to provide new broad spectrum antibacterials with novel modes of action. As a consequence, there is renewed interest in antibacterial targets which disrupt the capacity of pathogenic bacteria to cause infection by attenuating virulence. In this respect, one crucial feature of almost all bacterial infections is that the pathogen must attain a critical cell population density sufficient to overwhelm the host defences. Many pathogens are now known to regulate diverse physiological processes, including virulence, in a cell density dependent manner through cell-cell communication. This phenomenon, which relies upon the interaction of a diffusible signal molecule with a sensor kinase or response regulator, has become known as 'quorum sensing'. This review considers the molecular basis of quorum sensing and whether it constitutes a potential therapeutic target for the design of small molecule antagonists capable of controlling infection by attenuating adaptation to the host environment.
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Affiliation(s)
- Paul Williams
- Institute of Infections and Immunity, University of Nottingham, Queen's Medical Centre, Nottingham, NG7 2UH UK.
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29
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Winzer K, Hardie KR, Burgess N, Doherty N, Kirke D, Holden MTG, Linforth R, Cornell KA, Taylor AJ, Hill PJ, Williams P. LuxS: its role in central metabolism and the in vitro synthesis of 4-hydroxy-5-methyl-3(2H)-furanone. MICROBIOLOGY (READING, ENGLAND) 2002; 148:909-922. [PMID: 11932438 DOI: 10.1099/00221287-148-4-909] [Citation(s) in RCA: 274] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Many bacteria produce extracellular molecules which function in cell-to-cell communication. One of these molecules, autoinducer 2 (AI-2), was first described as an extracellular signal produced by Vibrio harveyi to control luciferase expression. Subsequently, a number of bacteria have been shown to possess AI-2 activity in their culture supernatants, and bear the luxS gene product, which is required for AI-2 synthesis. In Porphyromonas gingivalis, luxS and pfs, encoding a 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTA/SAH'ase), form an operon, suggesting that S-adenosylhomocysteine (SAH) or 5'-methylthioadenosine (MTA) serves as a substrate for AI-2 production. Cell-free extracts of Escherichia coli MG1655, but not DH5alpha (which carries a luxS frame-shift mutation) were capable of generating AI-2 activity upon addition of SAH, but not MTA. S-Ribosyl-homocysteine (RH) derived from SAH also served as a substrate in E. coli MG1655 extracts. RH-supplemented cell-free extracts of Pseudomonas aeruginosa, a bacterium that lacks luxS, only generated AI-2 activity following the introduction of a plasmid containing the Por. gingivalis pfs-luxS operon. In addition, defined in vitro systems consisting of the purified LuxS proteins from Por. gingivalis, E. coli, Neisseria meningitidis or Staphylococcus aureus converted RH to homocysteine and a compound that exhibits AI-2 activity.4-Hydroxy-5-methyl-3(2H)-furanone was identified by mass spectrometry analysis as a major product formed in this in vitro reaction. In E. coli MG1655, expression of T3SH [the bacteriophage T3 S-adenosylmethionine (SAM) hydrolase] significantly reduced AI-2 activity in culture supernatants, suggesting that AI-2 production is limited by the amount of SAH produced in SAM-dependent transmethylase reactions. The authors suggest that the LuxS protein has an important metabolic function in the recycling of SAH. They also show that Ps. aeruginosa is capable of removing AI-2 activity, implying that this molecule may act as a nutrient. In many bacteria AI-2 may in fact represent not a signal molecule but a metabolite which is released early and metabolized in the later stages of growth.
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Affiliation(s)
- Klaus Winzer
- Institute of Infections and Immunity, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK1
| | - Kim R Hardie
- School of Pharmaceutical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK2
- Institute of Infections and Immunity, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK1
| | - Nicola Burgess
- Institute of Infections and Immunity, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK1
| | - Neil Doherty
- Institute of Infections and Immunity, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK1
| | - David Kirke
- School of Pharmaceutical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK2
| | - Matthew T G Holden
- School of Pharmaceutical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK2
- Institute of Infections and Immunity, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK1
| | - Rob Linforth
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK3
| | - Kenneth A Cornell
- Immunology Research, R&D 21, VA Medical Center, Portland, OR 97201, USA4
| | - Andrew J Taylor
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK3
| | - Philip J Hill
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK3
- Institute of Infections and Immunity, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK1
| | - Paul Williams
- School of Pharmaceutical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK2
- Institute of Infections and Immunity, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK1
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Middleton B, Rodgers HC, Cámara M, Knox AJ, Williams P, Hardman A. Direct detection of N-acylhomoserine lactones in cystic fibrosis sputum. FEMS Microbiol Lett 2002; 207:1-7. [PMID: 11886742 DOI: 10.1111/j.1574-6968.2002.tb11019.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Pseudomonas aeruginosa and Burkholderia cepacia cause destructive lung disease in cystic fibrosis (CF) patients. Both pathogens employ 'quorum sensing', i.e. cell-to-cell communication, via diffusible N-acyl-L-homoserine lactone (AHL) signal molecules, to regulate the production of a number of virulence determinants in vitro. However, to date, evidence that quorum sensing systems are functional and play a role in vivo is lacking. This study presents the first direct evidence for the presence of AHLs in CF sputum. A total of 42 samples from 25 CF patients were analysed using lux-based Escherichia coli AHL biosensors. AHLs were detected in sputum from patients colonised by P. aeruginosa or B. cepacia but not Staphylococcus aureus. Furthermore, using liquid chromatography-mass spectrometry and thin layer chromatography, we confirmed the presence of N-hexanoylhomoserine lactone and N-(3-oxododecanoyl)homoserine lactone respectively in sputum samples from patients colonised by P. aeruginosa.
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Affiliation(s)
- Barry Middleton
- School of Pharmaceutical Sciences, University of Nottingham, University Park, NG7 2RD, UK
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