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Abstract
AbstractThe complex composition of bacterial membranes has a significant impact on the understanding of pathogen function and their development towards antibiotic resistance. In addition to the inherent complexity and biosafety risks of studying biological pathogen membranes, the continual rise of antibiotic resistance and its significant economical and clinical consequences has motivated the development of numerous in vitro model membrane systems with tuneable compositions, geometries, and sizes. Approaches discussed in this review include liposomes, solid-supported bilayers, and computational simulations which have been used to explore various processes including drug-membrane interactions, lipid-protein interactions, host–pathogen interactions, and structure-induced bacterial pathogenesis. The advantages, limitations, and applicable analytical tools of all architectures are summarised with a perspective for future research efforts in architectural improvement and elucidation of resistance development strategies and membrane-targeting antibiotic mechanisms.
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Goode A, Yeh V, Bonev BB. Interactions of polymyxin B with lipopolysaccharide-containing membranes. Faraday Discuss 2021; 232:317-329. [PMID: 34550139 PMCID: PMC8704168 DOI: 10.1039/d1fd00036e] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Bacterial resistance to antibiotics constantly remodels the battlefront between infections and antibiotic therapy. Polymyxin B, a cationic peptide with an anti-Gram-negative spectrum of activity is re-entering use as a last resort measure and as an adjuvant. We use fluorescence dequenching to investigate the role of the rough chemotype bacterial lipopolysaccharide from E. coli BL21 as a molecular facilitator of membrane disruption by LPS. The minimal polymyxin B/lipid ratio required for leakage onset increased from 5.9 × 10−4 to 1.9 × 10−7 in the presence of rLPS. We confirm polymyxin B activity against E. coli BL21 by the agar diffusion method and determined a MIC of 291 μg ml−1. Changes in lipid membrane stability and dynamics in response to polymyxin and the role of LPS are investigated by 31P NMR and high resolution 31P MAS NMR relaxation is used to monitor selective molecular interactions between polymyxin B and rLPS within bilayer lipid membranes. We observe a strong facilitating effect from rLPS on the membrane lytic properties of polymyxin B and a specific, pyrophosphate-mediated process of molecular recognition of LPS by polymyxin B. Polymyxin B uses bacterial LPS as docking receptor to cross the outer membrane.![]()
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Affiliation(s)
- Alice Goode
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, NG7 2UH, UK.
| | - Vivien Yeh
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, NG7 2UH, UK.
| | - Boyan B Bonev
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, NG7 2UH, UK.
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3
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Startek JB, Talavera K. Lipid Raft Destabilization Impairs Mouse TRPA1 Responses to Cold and Bacterial Lipopolysaccharides. Int J Mol Sci 2020; 21:E3826. [PMID: 32481567 PMCID: PMC7312353 DOI: 10.3390/ijms21113826] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 05/21/2020] [Accepted: 05/27/2020] [Indexed: 12/15/2022] Open
Abstract
The Transient Receptor Potential ankyrin 1 cation channel (TRPA1) is expressed in nociceptive sensory neurons and epithelial cells, where it plays key roles in the detection of noxious stimuli. Recent reports showed that mouse TRPA1 (mTRPA1) localizes in lipid rafts and that its sensitivity to electrophilic and non-electrophilic agonists is reduced by cholesterol depletion from the plasma membrane. Since effects of manipulating membrane cholesterol levels on other TRP channels are known to vary across different stimuli we here tested whether the disruption of lipid rafts also affects mTRPA1 activation by cold or bacterial lipopolysaccharides (LPS). Cooling to 12 °C, E. coli LPS and allyl isothiocyanate (AITC) induced robust Ca2+ responses in CHO-K1 cells stably transfected with mTRPA1. The amplitudes of the responses to these stimuli were significantly lower in cells treated with the cholesterol scavenger methyl β-cyclodextrin (MCD) or with the sphingolipids hydrolyzer sphingomyelinase (SMase). This effect was more prominent with higher concentrations of the raft destabilizers. Our data also indicate that reduction of cholesterol does not alter the expression of mTRPA1 in the plasma membrane in the CHO-K1 stable expression system, and that the most salient effect is that on the channel gating. Our findings further indicate that the function of mTRPA1 is regulated by the local lipid environment and suggest that targeting lipid-TRPA1 interactions may be a strategy for the treatment of pain and neurogenic inflammation.
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Affiliation(s)
| | - Karel Talavera
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain & Disease Research, Herestraat 49, Campus Gasthuisberg O&N1 bus 802, 3000 Leuven, Belgium;
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Barbosa SC, Nobre TM, Volpati D, Cilli EM, Correa DS, Oliveira ON. The cyclic peptide labaditin does not alter the outer membrane integrity of Salmonella enterica serovar Typhimurium. Sci Rep 2019; 9:1993. [PMID: 30760803 PMCID: PMC6374527 DOI: 10.1038/s41598-019-38551-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 12/27/2018] [Indexed: 12/21/2022] Open
Abstract
Antimicrobial peptides are a promising class of new antibiotics with the ability to kill bacteria by disrupting their cell membrane, which is especially difficult for Gram-negative bacteria whose cell wall contains an outer layer of lipopolysaccharides (LPS). Here we show that the cyclic decapeptide Labaditin (Lo), with proven activity against the Gram-positive Staphylococcus aureus and Streptococcus mutans, is not able to kill the Gram-negative Salmonella enterica serovar Typhimurium (S.e.s. Typhimurium). We found that Lo induced significant changes in the surface pressure isotherms of Langmuir monolayers representing the Salmonella enterica serovar Typhimurium inner membrane (S.e.s. Typhimurium IM), and caused leakage in large unilamellar vesicles made with this IM lipid composition. On the basis of these results one should expect bactericidal activity against S.e.s. Typhimurium. However, Lo could not interact with a monolayer of LPS, causing no significant changes in either the surface pressure isotherms or in the polarization-modulated infrared reflection absorption spectra (PM-IRRAS). Therefore, the failure of Lo to kill S.e.s. Typhimurium is associated with the lack of interaction with LPS from the outer bacteria membrane. Our approach with distinct monolayer compositions and combined techniques to investigate molecular-level interactions is useful for drug design to fight antibiotic-resistant bacteria.
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Affiliation(s)
- Simone C Barbosa
- São Carlos Institute of Physics, University of São Paulo, CP 369, 13560-970, São Carlos-SP, Brazil
| | - Thatyane M Nobre
- São Carlos Institute of Physics, University of São Paulo, CP 369, 13560-970, São Carlos-SP, Brazil
| | | | - Eduardo M Cilli
- Universidade Estadual Paulista (UNESP), Institute of Chemistry, 14800-060, Araraquara-SP, Brazil
| | - Daniel S Correa
- Nanotechnology National Laboratory for Agriculture (LNNA), Embrapa Instrumentação, 13560-970, São Carlos, SP, Brazil
| | - Osvaldo N Oliveira
- São Carlos Institute of Physics, University of São Paulo, CP 369, 13560-970, São Carlos-SP, Brazil.
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Karaś MA, Turska-Szewczuk A, Janczarek M, Szuster-Ciesielska A. Glycoconjugates of Gram-negative bacteria and parasitic protozoa - are they similar in orchestrating the innate immune response? Innate Immun 2019; 25:73-96. [PMID: 30782045 PMCID: PMC6830889 DOI: 10.1177/1753425918821168] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 12/03/2018] [Indexed: 02/06/2023] Open
Abstract
Innate immunity is an evolutionarily ancient form of host defense that serves to limit infection. The invading microorganisms are detected by the innate immune system through germline-encoded PRRs. Different classes of PRRs, including TLRs and cytoplasmic receptors, recognize distinct microbial components known collectively as PAMPs. Ligation of PAMPs with receptors triggers intracellular signaling cascades, activating defense mechanisms. Despite the fact that Gram-negative bacteria and parasitic protozoa are phylogenetically distant organisms, they express glycoconjugates, namely bacterial LPS and protozoan GPI-anchored glycolipids, which share many structural and functional similarities. By activating/deactivating MAPK signaling and NF-κB, these ligands trigger general pro-/anti-inflammatory responses depending on the related patterns. They also use conservative strategies to subvert cell-autonomous defense systems of specialized immune cells. Signals triggered by Gram-negative bacteria and parasitic protozoa can interfere with host homeostasis and, depending on the type of microorganism, lead to hypersensitivity or silencing of the immune response. Activation of professional immune cells, through a ligand which triggers the opposite effect (antagonist versus agonist) appears to be a promising solution to restoring the immune balance.
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Affiliation(s)
- Magdalena A Karaś
- Department of Genetics and Microbiology, Maria Curie–Skłodowska
University, Lublin, Poland
| | - Anna Turska-Szewczuk
- Department of Genetics and Microbiology, Maria Curie–Skłodowska
University, Lublin, Poland
| | - Monika Janczarek
- Department of Genetics and Microbiology, Maria Curie–Skłodowska
University, Lublin, Poland
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Lanne ABM, Goode A, Prattley C, Kumari D, Drasbek MR, Williams P, Conde-Álvarez R, Moriyón I, Bonev BB. Molecular recognition of lipopolysaccharide by the lantibiotic nisin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1861:83-92. [PMID: 30296414 DOI: 10.1016/j.bbamem.2018.10.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 10/02/2018] [Accepted: 10/03/2018] [Indexed: 01/01/2023]
Abstract
Nisin is a lanthionine antimicrobial effective against diverse Gram-positive bacteria and is used as a food preservative worldwide. Its action is mediated by pyrophosphate recognition of the bacterial cell wall receptors lipid II and undecaprenyl pyrophosphate. Nisin/receptor complexes disrupt cytoplasmic membranes, inhibit cell wall synthesis and dysregulate bacterial cell division. Gram-negative bacteria are much more tolerant to antimicrobials including nisin. In contrast to Gram-positives, Gram-negative bacteria possess an outer membrane, the major constituent of which is lipopolysaccharide (LPS). This contains surface exposed phosphate and pyrophosphate groups and hence can be targeted by nisin. Here we describe the impact of LPS on membrane stability in response to nisin and the molecular interactions occurring between nisin and membrane-embedded LPS from different Gram-negative bacteria. Dye release from liposomes shows enhanced susceptibility to nisin in the presence of LPS, particularly rough LPS chemotypes that lack an O-antigen whereas LPS from microorganisms sharing similar ecological niches with antimicrobial producers provides only modest enhancement. Increased susceptibility was observed with LPS from pathogenic Klebsiella pneumoniae compared to LPS from enteropathogenic Salmonella enterica and gut commensal Escherichia coli. LPS from Brucella melitensis, an intra-cellular pathogen which is adapted to invade professional and non-professional phagocytes, appears to be refractory to nisin. Molecular complex formation between nisin and LPS was studied by solid state MAS NMR and revealed complex formation between nisin and LPS from most organisms investigated except B. melitensis. LPS/nisin complex formation was confirmed in outer membrane extracts from E. coli.
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Affiliation(s)
- Alice B M Lanne
- School of Life Sciences, QMC, University of Nottingham, Nottingham NG7 2UH, UK
| | - Alice Goode
- School of Life Sciences, QMC, University of Nottingham, Nottingham NG7 2UH, UK
| | - Charlotte Prattley
- School of Life Sciences, QMC, University of Nottingham, Nottingham NG7 2UH, UK
| | - Divya Kumari
- School of Life Sciences, QMC, University of Nottingham, Nottingham NG7 2UH, UK
| | - Mette Ryun Drasbek
- DuPont Nutrition Biosciences ApS, Edwin Rahrs Vej 38, DK-8220 Brabrand, Denmark
| | - Paul Williams
- School of Life Sciences, CBS, University of Nottingham, Nottingham NG7 2RD, UK
| | - Raquel Conde-Álvarez
- Instituto de Salud Tropical, Instituto de Investigación Sanitaria de Navarra, and Departamento de Microbiología y Parasitología, Universidad de Navarra, c/Irunlarrea 1, 31008 Pamplona, Spain
| | - Ignacio Moriyón
- Instituto de Salud Tropical, Instituto de Investigación Sanitaria de Navarra, and Departamento de Microbiología y Parasitología, Universidad de Navarra, c/Irunlarrea 1, 31008 Pamplona, Spain
| | - Boyan B Bonev
- School of Life Sciences, QMC, University of Nottingham, Nottingham NG7 2UH, UK.
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Kell DB, Pretorius E. On the translocation of bacteria and their lipopolysaccharides between blood and peripheral locations in chronic, inflammatory diseases: the central roles of LPS and LPS-induced cell death. Integr Biol (Camb) 2016; 7:1339-77. [PMID: 26345428 DOI: 10.1039/c5ib00158g] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We have recently highlighted (and added to) the considerable evidence that blood can contain dormant bacteria. By definition, such bacteria may be resuscitated (and thus proliferate). This may occur under conditions that lead to or exacerbate chronic, inflammatory diseases that are normally considered to lack a microbial component. Bacterial cell wall components, such as the endotoxin lipopolysaccharide (LPS) of Gram-negative strains, are well known as potent inflammatory agents, but should normally be cleared. Thus, their continuing production and replenishment from dormant bacterial reservoirs provides an easy explanation for the continuing, low-grade inflammation (and inflammatory cytokine production) that is characteristic of many such diseases. Although experimental conditions and determinants have varied considerably between investigators, we summarise the evidence that in a great many circumstances LPS can play a central role in all of these processes, including in particular cell death processes that permit translocation between the gut, blood and other tissues. Such localised cell death processes might also contribute strongly to the specific diseases of interest. The bacterial requirement for free iron explains the strong co-existence in these diseases of iron dysregulation, LPS production, and inflammation. Overall this analysis provides an integrative picture, with significant predictive power, that is able to link these processes via the centrality of a dormant blood microbiome that can resuscitate and shed cell wall components.
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Affiliation(s)
- Douglas B Kell
- School of Chemistry and The Manchester Institute of Biotechnology, The University of Manchester, 131, Princess St, Manchester M1 7DN, Lancs, UK.
| | - Etheresia Pretorius
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, Arcadia 0007, South Africa.
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8
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Martins IJ. Magnesium Therapy Prevents Senescence with the Reversal of Diabetes and Alzheimer’s Disease. Health (London) 2016. [DOI: 10.4236/health.2016.87073] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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9
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Nagel M, Brauckmann S, Moegle-Hofacker F, Effenberger-Neidnicht K, Hartmann M, de Groot H, Mayer C. Impact of bacterial endotoxin on the structure of DMPC membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:2271-6. [DOI: 10.1016/j.bbamem.2015.06.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 06/03/2015] [Accepted: 06/07/2015] [Indexed: 12/22/2022]
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10
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Garcia IJP, Kinoshita PF, Scavone C, Mignaco JA, de Oliveira Barbosa LA, de Lima Santos H. Ouabain Modulates the Lipid Composition of Hippocampal Plasma Membranes from Rats with LPS-induced Neuroinflammation. J Membr Biol 2015; 248:1191-8. [DOI: 10.1007/s00232-015-9840-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 09/04/2015] [Indexed: 12/21/2022]
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11
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Exploiting lipopolysaccharide-induced deformation of lipid bilayers to modify membrane composition and generate two-dimensional geometric membrane array patterns. Sci Rep 2015; 5:10331. [PMID: 26015293 PMCID: PMC4444833 DOI: 10.1038/srep10331] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 04/08/2015] [Indexed: 12/31/2022] Open
Abstract
Supported lipid bilayers have proven effective as model membranes for investigating biophysical processes and in development of sensor and array technologies. The ability to modify lipid bilayers after their formation and in situ could greatly advance membrane technologies, but is difficult via current state-of-the-art technologies. Here we demonstrate a novel method that allows the controlled post-formation processing and modification of complex supported lipid bilayer arrangements, under aqueous conditions. We exploit the destabilization effect of lipopolysaccharide, an amphiphilic biomolecule, interacting with lipid bilayers to generate voids that can be backfilled to introduce desired membrane components. We further demonstrate that when used in combination with a single, traditional soft lithography process, it is possible to generate hierarchically-organized membrane domains and microscale 2-D array patterns of domains. Significantly, this technique can be used to repeatedly modify membranes allowing iterative control over membrane composition. This approach expands our toolkit for functional membrane design, with potential applications for enhanced materials templating, biosensing and investigating lipid-membrane processes.
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12
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Ranf S, Gisch N, Schäffer M, Illig T, Westphal L, Knirel YA, Sánchez-Carballo PM, Zähringer U, Hückelhoven R, Lee J, Scheel D. A lectin S-domain receptor kinase mediates lipopolysaccharide sensing in Arabidopsis thaliana. Nat Immunol 2015; 16:426-33. [PMID: 25729922 DOI: 10.1038/ni.3124] [Citation(s) in RCA: 221] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 02/11/2014] [Indexed: 12/25/2022]
Abstract
The sensing of microbe-associated molecular patterns (MAMPs) triggers innate immunity in animals and plants. Lipopolysaccharide (LPS) from Gram-negative bacteria is a potent MAMP for mammals, with the lipid A moiety activating proinflammatory responses via Toll-like receptor 4 (TLR4). Here we found that the plant Arabidopsis thaliana specifically sensed LPS of Pseudomonas and Xanthomonas. We isolated LPS-insensitive mutants defective in the bulb-type lectin S-domain-1 receptor-like kinase LORE (SD1-29), which were hypersusceptible to infection with Pseudomonas syringae. Targeted chemical degradation of LPS from Pseudomonas species suggested that LORE detected mainly the lipid A moiety of LPS. LORE conferred sensitivity to LPS onto tobacco after transient expression, which demonstrated a key function in LPS sensing and indicated the possibility of engineering resistance to bacteria in crop species.
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Affiliation(s)
- Stefanie Ranf
- 1] Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, Halle, Germany. [2] Phytopathology, TUM School of Life Sciences Weihenstephan, Technische Universität München, Freising-Weihenstephan, Germany
| | - Nicolas Gisch
- Division of Immunochemistry/Bioanalytical Chemistry, Priority Area Infections, Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Borstel, Germany
| | - Milena Schäffer
- Phytopathology, TUM School of Life Sciences Weihenstephan, Technische Universität München, Freising-Weihenstephan, Germany
| | - Tina Illig
- Phytopathology, TUM School of Life Sciences Weihenstephan, Technische Universität München, Freising-Weihenstephan, Germany
| | - Lore Westphal
- Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, Halle, Germany
| | - Yuriy A Knirel
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Patricia M Sánchez-Carballo
- Division of Immunochemistry/Bioanalytical Chemistry, Priority Area Infections, Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Borstel, Germany
| | - Ulrich Zähringer
- Division of Immunochemistry/Bioanalytical Chemistry, Priority Area Infections, Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Borstel, Germany
| | - Ralph Hückelhoven
- Phytopathology, TUM School of Life Sciences Weihenstephan, Technische Universität München, Freising-Weihenstephan, Germany
| | - Justin Lee
- Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, Halle, Germany
| | - Dierk Scheel
- Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, Halle, Germany
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13
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Ruysschaert JM, Lonez C. Role of lipid microdomains in TLR-mediated signalling. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1860-7. [PMID: 25797518 DOI: 10.1016/j.bbamem.2015.03.014] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 03/09/2015] [Accepted: 03/12/2015] [Indexed: 12/13/2022]
Abstract
Over the last twenty years, evidence has been provided that the plasma membrane is partitioned with microdomains, laterally mobile in the bilayer, providing the necessary microenvironment to specific membrane proteins for signalling pathways to be initiated. We discuss here the importance of such microdomains for Toll-like receptors (TLR) localization and function. First, lipid microdomains favour recruitment and clustering of the TLR machinery partners, i.e. receptors and co-receptors previously identified to be required for ligand recognition and signal transmission. Further, the presence of the so-called Cholesterol Recognition Amino-Acid Consensus (CRAC) sequences in the intracellular juxtamembrane domain of several Toll-like receptors suggests a direct role of cholesterol in the activation process. This article is part of a Special Issue entitled: Lipid-protein interactions.
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Affiliation(s)
- Jean-Marie Ruysschaert
- Structure and Function of Biological Membranes, Université Libre de Bruxelles, Boulevard du Triomphe, 1050 Brussels, Belgium
| | - Caroline Lonez
- Structure and Function of Biological Membranes, Université Libre de Bruxelles, Boulevard du Triomphe, 1050 Brussels, Belgium; Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom.
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14
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Beck Z, Matyas GR, Alving CR. Detection of liposomal cholesterol and monophosphoryl lipid A by QS-21 saponin and Limulus polyphemus amebocyte lysate. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:775-80. [DOI: 10.1016/j.bbamem.2014.12.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 11/26/2014] [Accepted: 12/05/2014] [Indexed: 11/16/2022]
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15
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Johnson CL, Ridley H, Marchetti R, Silipo A, Griffin DC, Crawford L, Bonev B, Molinaro A, Lakey JH. The antibacterial toxin colicin N binds to the inner core of lipopolysaccharide and close to its translocator protein. Mol Microbiol 2014; 92:440-52. [PMID: 24589252 PMCID: PMC4114557 DOI: 10.1111/mmi.12568] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2014] [Indexed: 12/03/2022]
Abstract
Colicins are a diverse family of large antibacterial protein toxins, secreted by and active against Escherichia coli and must cross their target cell's outer membrane barrier to kill. To achieve this, most colicins require an abundant porin (e.g. OmpF) plus a low‐copy‐number, high‐affinity, outer membrane protein receptor (e.g. BtuB). Recently, genetic screens have suggested that colicin N (ColN), which has no high‐affinity receptor, targets highly abundant lipopolysaccharide (LPS) instead. Here we reveal the details of this interaction and demonstrate that the ColN receptor‐binding domain (ColN‐R) binds to a specific region of LPS close to the membrane surface. Data from in vitro studies using calorimetry and both liquid‐ and solid‐state NMR reveal the interactions behind the in vivo requirement for a defined oligosaccharide region of LPS. Delipidated LPS (LPSΔLIPID) shows weaker binding; and thus full affinity requires the lipid component. The site of LPS binding means that ColN will preferably bind at the interface and thus position itself close to the surface of its translocon component, OmpF. ColN is, currently, unique among colicins in requiring LPS and, combined with previous data, this implies that the ColN translocon is distinct from those of other known colicins.
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Affiliation(s)
- Christopher L Johnson
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Framlington Place, Newcastle-upon-Tyne, NE2 4HH, UK
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16
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Huster D. Solid-state NMR spectroscopy to study protein-lipid interactions. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1841:1146-60. [PMID: 24333800 DOI: 10.1016/j.bbalip.2013.12.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 12/04/2013] [Indexed: 12/22/2022]
Abstract
The appropriate lipid environment is crucial for the proper function of membrane proteins. There is a tremendous variety of lipid molecules in the membrane and so far it is often unclear which component of the lipid matrix is essential for the function of a respective protein. Lipid molecules and proteins mutually influence each other; parameters such as acyl chain order, membrane thickness, membrane elasticity, permeability, lipid-domain and annulus formation are strongly modulated by proteins. More recent data also indicates that the influence of proteins goes beyond a single annulus of next-neighbor boundary lipids. Therefore, a mesoscopic approach to membrane lipid-protein interactions in terms of elastic membrane deformations has been developed. Solid-state NMR has greatly contributed to the understanding of lipid-protein interactions and the modern view of biological membranes. Methods that detect the influence of proteins on the membrane as well as direct lipid-protein interactions have been developed and are reviewed here. Examples for solid-state NMR studies on the interaction of Ras proteins, the antimicrobial peptide protegrin-1, the G protein-coupled receptor rhodopsin, and the K(+) channel KcsA are discussed. This article is part of a Special Issue entitled Tools to study lipid functions.
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Affiliation(s)
- Daniel Huster
- Institute of Medical Physics and Biophysics, University of Leipzig, Härtelstr. 16-18, D-04107 Leipzig, Germany.
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