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Andersson J, Kleinheinz D, Ramach U, Kiesenhofer N, Ashenden A, Valtiner M, Holt S, Koeper I, Schmidpeter PAM, Knoll W. Native Function of the Bacterial Ion Channel SthK in a Sparsely Tethered Lipid Bilayer Membrane Architecture. J Phys Chem B 2023; 127:3641-3650. [PMID: 37072125 PMCID: PMC10150356 DOI: 10.1021/acs.jpcb.2c07252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
Abstract
The plasma membrane protects the interiors of cells from their surroundings and also plays a critical role in communication, sensing, and nutrient import. As a result, the cell membrane and its constituents are among the most important drug targets. Studying the cell membrane and the processes it facilitates is therefore crucial, but it is a highly complex environment that is difficult to access experimentally. Various model membrane systems have been developed to provide an environment in which membrane proteins can be studied in isolation. Among them, tethered bilayer lipid membranes (tBLMs) are a promising model system providing a solvent-free membrane environment which can be prepared by self-assembly, is resistant to mechanical disturbances and has a high electrical resistance. tBLMs are therefore uniquely suitable to study ion channels and charge transport processes. However, ion channels are often large, complex, multimeric structures and their function requires a particular lipid environment. In this paper, we show that SthK, a bacterial cyclic nucleotide gated (CNG) ion channel that is strongly dependent on the surrounding lipid composition, functions normally when embedded into a sparsely tethered lipid bilayer. As SthK has been very well characterized in terms of structure and function, it is well-suited to demonstrate the utility of tethered membrane systems. A model membrane system suitable for studying CNG ion channels would be useful, as this type of ion channel performs a wide range of physiological functions in bacteria, plants, and mammals and is therefore of fundamental scientific interest as well as being highly relevant to medicine.
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Affiliation(s)
- Jakob Andersson
- Austrian Institute of Technology GmbH, Giefinggasse 4, 1210 Vienna, Austria
| | - David Kleinheinz
- Austrian Institute of Technology GmbH, Giefinggasse 4, 1210 Vienna, Austria
| | - Ulrich Ramach
- Technische Universität Wien, Wiedner Hauptstr. 8-10/134, 1040 Wien, Austria
- CEST Kompetenzzentrum für Oberflächentechnologie, Viktor Kaplan-Straße 2, 2700 Wiener Neustadt, Austria
| | | | - Alex Ashenden
- Flinders University of South Australia, Bedford Park SA, 5042 Adelaide, Australia
| | - Markus Valtiner
- Technische Universität Wien, Wiedner Hauptstr. 8-10/134, 1040 Wien, Austria
- CEST Kompetenzzentrum für Oberflächentechnologie, Viktor Kaplan-Straße 2, 2700 Wiener Neustadt, Austria
| | - Stephen Holt
- Australian Nuclear Science and Technology Organization, New Illawarra Rd, Lucas Heights, NSW 2234, Australia
| | - Ingo Koeper
- Flinders University of South Australia, Bedford Park SA, 5042 Adelaide, Australia
| | - Philipp A M Schmidpeter
- Weill Cornell Medicine, Department of Anesthesiology, 1300 York Avenue, New York, New York 10065, United States
| | - Wolfgang Knoll
- Austrian Institute of Technology GmbH, Giefinggasse 4, 1210 Vienna, Austria
- Danube Private University, Steiner Landstraße 124, 3500 Krems an der Donau, Austria
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2
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Glucocorticoids increase tissue cell protection against pore-forming toxins from pathogenic bacteria. Commun Biol 2023; 6:186. [PMID: 36807406 PMCID: PMC9938277 DOI: 10.1038/s42003-023-04568-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 02/09/2023] [Indexed: 02/19/2023] Open
Abstract
Many species of pathogenic bacteria damage tissue cells by secreting toxins that form pores in plasma membranes. Here we show that glucocorticoids increase the intrinsic protection of tissue cells against pore-forming toxins. Dexamethasone protected several cell types against the cholesterol-dependent cytolysin, pyolysin, from Trueperella pyogenes. Dexamethasone treatment reduced pyolysin-induced leakage of potassium and lactate dehydrogenase, limited actin cytoskeleton alterations, reduced plasma membrane blebbing, and prevented cytolysis. Hydrocortisone and fluticasone also protected against pyolysin-induced cell damage. Furthermore, dexamethasone protected HeLa and A549 cells against the pore-forming toxins streptolysin O from Streptococcus pyogenes, and alpha-hemolysin from Staphylococcus aureus. Dexamethasone cytoprotection was not associated with changes in cellular cholesterol or activating mitogen-activated protein kinase (MAPK) cell stress responses. However, cytoprotection was dependent on the glucocorticoid receptor and 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR). Collectively, our findings imply that glucocorticoids could be exploited to limit tissue damage caused by pathogens secreting pore-forming toxins.
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3
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Gabriunaite I, Valiuniene A, Ramanavicius S, Ramanavicius A. Biosensors Based on Bio-Functionalized Semiconducting Metal Oxides. Crit Rev Anal Chem 2022; 54:549-564. [PMID: 35714203 DOI: 10.1080/10408347.2022.2088226] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Immobilization of biomaterials is a very important task in the development of biofuel cells and biosensors. Some semiconducting metal-oxide-based supporting materials can be used in these bioelectronics-based devices. In this article, we are reviewing some functionalization methods that are applied for the immobilization of biomaterials. The most significant attention is paid to the immobilization of biomolecules on the surface of semiconducting metal oxides. The improvement of biomaterials immobilization on metal oxides and analytical performance of biosensors by coatings based on conducting polymers, self-assembled monolayers and lipid membranes is discussed.
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Affiliation(s)
- Inga Gabriunaite
- Vilnius University, Faculty of Chemistry and Geosciences, Institute of Chemistry, Department of Physical Chemistry, Vilnius, Lithuania
| | - Ausra Valiuniene
- Vilnius University, Faculty of Chemistry and Geosciences, Institute of Chemistry, Department of Physical Chemistry, Vilnius, Lithuania
| | - Simonas Ramanavicius
- Centre for Physical Sciences and Technology, Department of Electrochemical Material Science, Vilnius, Lithuania
| | - Arunas Ramanavicius
- Vilnius University, Faculty of Chemistry and Geosciences, Institute of Chemistry, Department of Physical Chemistry, Vilnius, Lithuania
- Centre for Physical Sciences and Technology, Department of Electrochemical Material Science, Vilnius, Lithuania
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4
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Di Leone S, Kyropoulou M, Köchlin J, Wehr R, Meier WP, Palivan CG. Tailoring a Solvent-Assisted Method for Solid-Supported Hybrid Lipid-Polymer Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:6561-6570. [PMID: 35580858 PMCID: PMC9161443 DOI: 10.1021/acs.langmuir.2c00204] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 04/11/2022] [Indexed: 06/15/2023]
Abstract
Combining amphiphilic block copolymers and phospholipids opens new opportunities for the preparation of artificial membranes. The chemical versatility and mechanical robustness of polymers together with the fluidity and biocompatibility of lipids afford hybrid membranes with unique properties that are of great interest in the field of bioengineering. Owing to its straightforwardness, the solvent-assisted method (SA) is particularly attractive for obtaining solid-supported membranes. While the SA method was first developed for lipids and very recently extended to amphiphilic block copolymers, its potential to develop hybrid membranes has not yet been explored. Here, we tailor the SA method to prepare solid-supported polymer-lipid hybrid membranes by combining a small library of amphiphilic diblock copolymers poly(dimethyl siloxane)-poly(2-methyl-2-oxazoline) and poly(butylene oxide)-block-poly(glycidol) with phospholipids commonly found in cell membranes including 1,2-dihexadecanoyl-sn-glycero-3-phosphocholine, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine, sphingomyelin, and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-(glutaryl). The optimization of the conditions under which the SA method was applied allowed for the formation of hybrid polymer-lipid solid-supported membranes. The real-time formation and morphology of these hybrid membranes were evaluated using a combination of quartz crystal microbalance and atomic force microscopy. Depending on the type of polymer-lipid combination, significant differences in membrane coverage, formation of domains, and quality of membranes were obtained. The use of the SA method for a rapid and controlled formation of solid-supported hybrid membranes provides the basis for developing customized artificial hybrid membranes.
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Affiliation(s)
- Stefano Di Leone
- Department
of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, 4058 Basel, Switzerland
- School
of Life Sciences, Institute for Chemistry and Bioanalytics, University of Applied Sciences Northwestern Switzerland
(FHNW), Grundenstrasse
40, 4132 Muttenz, Switzerland
| | - Myrto Kyropoulou
- Department
of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, 4058 Basel, Switzerland
- National
Centre of Competence in Research Molecular Systems Engineering (NCCR
MSE), BPR 1095, Mattenstrasse
24a, 4058 Basel, Switzerland
| | - Julian Köchlin
- Department
of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, 4058 Basel, Switzerland
| | - Riccardo Wehr
- Department
of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, 4058 Basel, Switzerland
| | - Wolfgang P. Meier
- Department
of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, 4058 Basel, Switzerland
- National
Centre of Competence in Research Molecular Systems Engineering (NCCR
MSE), BPR 1095, Mattenstrasse
24a, 4058 Basel, Switzerland
| | - Cornelia G. Palivan
- Department
of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, 4058 Basel, Switzerland
- National
Centre of Competence in Research Molecular Systems Engineering (NCCR
MSE), BPR 1095, Mattenstrasse
24a, 4058 Basel, Switzerland
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5
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Membrane Cholesterol Content and Lipid Organization Influence Melittin and Pneumolysin Pore-Forming Activity. Toxins (Basel) 2022; 14:toxins14050346. [PMID: 35622592 PMCID: PMC9147762 DOI: 10.3390/toxins14050346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/03/2022] [Accepted: 05/06/2022] [Indexed: 12/12/2022] Open
Abstract
Melittin, the main toxic component in the venom of the European honeybee, interacts with natural and artificial membranes due to its amphiphilic properties. Rather than interacting with a specific receptor, melittin interacts with the lipid components, disrupting the lipid bilayer and inducing ion leakage and osmotic shock. This mechanism of action is shared with pneumolysin and other members of the cholesterol-dependent cytolysin family. In this manuscript, we investigated the inverse correlation for cholesterol dependency of these two toxins. While pneumolysin-induced damage is reduced by pretreatment with the cholesterol-depleting agent methyl-β-cyclodextrin, the toxicity of melittin, after cholesterol depletion, increased. A similar response was also observed after a short incubation with lipophilic simvastatin, which alters membrane lipid organization and structure, clustering lipid rafts. Therefore, changes in toxin sensitivity can be achieved in cells by depleting cholesterol or changing the lipid bilayer organization.
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6
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Ormsby TJR, Owens SE, Clement L, Mills TJ, Cronin JG, Bromfield JJ, Sheldon IM. Oxysterols Protect Epithelial Cells Against Pore-Forming Toxins. Front Immunol 2022; 13:815775. [PMID: 35154132 PMCID: PMC8825411 DOI: 10.3389/fimmu.2022.815775] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 01/05/2022] [Indexed: 12/25/2022] Open
Abstract
Many species of bacteria produce toxins such as cholesterol-dependent cytolysins that form pores in cell membranes. Membrane pores facilitate infection by releasing nutrients, delivering virulence factors, and causing lytic cell damage - cytolysis. Oxysterols are oxidized forms of cholesterol that regulate cellular cholesterol and alter immune responses to bacteria. Whether oxysterols also influence the protection of cells against pore-forming toxins is unresolved. Here we tested the hypothesis that oxysterols stimulate the intrinsic protection of epithelial cells against damage caused by cholesterol-dependent cytolysins. We treated epithelial cells with oxysterols and then challenged them with the cholesterol-dependent cytolysin, pyolysin. Treating HeLa cells with 27-hydroxycholesterol, 25-hydroxycholesterol, 7α-hydroxycholesterol, or 7β-hydroxycholesterol reduced pyolysin-induced leakage of lactate dehydrogenase and reduced pyolysin-induced cytolysis. Specifically, treatment with 10 ng/ml 27-hydroxycholesterol for 24 h reduced pyolysin-induced lactate dehydrogenase leakage by 88%, and reduced cytolysis from 74% to 1%. Treating HeLa cells with 27-hydroxycholesterol also reduced pyolysin-induced leakage of potassium ions, prevented mitogen-activated protein kinase cell stress responses, and limited alterations in the cytoskeleton. Furthermore, 27-hydroxycholesterol reduced pyolysin-induced damage in lung and liver epithelial cells, and protected against the cytolysins streptolysin O and Staphylococcus aureus α-hemolysin. Although oxysterols regulate cellular cholesterol by activating liver X receptors, cytoprotection did not depend on liver X receptors or changes in total cellular cholesterol. However, oxysterol cytoprotection was partially dependent on acyl-CoA:cholesterol acyltransferase (ACAT) reducing accessible cholesterol in cell membranes. Collectively, these findings imply that oxysterols stimulate the intrinsic protection of epithelial cells against pore-forming toxins and may help protect tissues against pathogenic bacteria.
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Affiliation(s)
- Thomas J R Ormsby
- Swansea University Medical School, Swansea University, Swansea, United Kingdom
| | - Sian E Owens
- Swansea University Medical School, Swansea University, Swansea, United Kingdom
| | - Liam Clement
- Swansea University Medical School, Swansea University, Swansea, United Kingdom
| | - Tom J Mills
- Swansea University Medical School, Swansea University, Swansea, United Kingdom
| | - James G Cronin
- Swansea University Medical School, Swansea University, Swansea, United Kingdom
| | - John J Bromfield
- Department of Animal Sciences, University of Florida, Gainesville, FL, United States
| | - Iain Martin Sheldon
- Swansea University Medical School, Swansea University, Swansea, United Kingdom
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Ambrulevičius F, Valinčius G. Electrochemical impedance spectrum reveals structural details of distribution of pores and defects in supported phospholipid bilayers. Bioelectrochemistry 2022; 146:108092. [DOI: 10.1016/j.bioelechem.2022.108092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/23/2022] [Accepted: 02/26/2022] [Indexed: 11/15/2022]
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8
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AI-based atomic force microscopy image analysis allows to predict electrochemical impedance spectra of defects in tethered bilayer membranes. Sci Rep 2022; 12:1127. [PMID: 35064137 PMCID: PMC8783026 DOI: 10.1038/s41598-022-04853-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 12/24/2021] [Indexed: 01/08/2023] Open
Abstract
Atomic force microscopy (AFM) image analysis of supported bilayers, such as tethered bilayer membranes (tBLMs) can reveal the nature of the membrane damage by pore-forming proteins and predict the electrochemical impedance spectroscopy (EIS) response of such objects. However, automated analysis involving pore detection in such images is often non-trivial and can require AI-based object detection techniques. The specific object-detection algorithm we used to determine the defect coordinates in real AFM images was a convolutional neural network (CNN). Defect coordinates allow to predict the EIS response of tBLMs populated by the pore-forming toxins using finite element analysis (FEA) modeling. We tested if the accuracy of the CNN algorithm affected the EIS spectral features sensitive to defect densities and other physical parameters of tBLMs. We found that the EIS spectra can be predicted sufficiently well, however, systematic errors of characteristic spectral points were observed and need to be taken into account. Importantly, the comparison of predicted EIS curves with experimental ones allowed to estimate important physical parameters of tBLMs such as the specific resistance of submembrane reservoir. This reservoir separates phospholipid bilayer from the solid support. We found that the specific resistance of the reservoir amounts to \documentclass[12pt]{minimal}
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\begin{document}$$10^{4.25 \pm 0.10}$$\end{document}104.25±0.10\documentclass[12pt]{minimal}
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\begin{document}$$\Omega \cdot cm$$\end{document}Ω·cm which is approximately two orders of a magnitude higher compared to the specific resistance of the buffer bathing tBLMs studied in this work. We hypothesize that such effect may be related in part due to decreased concentration of ionic carriers in the submembrane due to decreased relative dielectric permittivity in this region.
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9
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Guidelli R, Becucci L. Functional activity of peptide ion channels in tethered bilayer lipid membranes: Review. ELECTROCHEMICAL SCIENCE ADVANCES 2021. [DOI: 10.1002/elsa.202100180] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Rolando Guidelli
- Department of Chemistry University of Florence Sesto Fiorentino Firenze Italy
| | - Lucia Becucci
- Ministero dell'Istruzione Scuola Media “Guglielmo Marconi” San Giovanni Valdarno Arezzo Italy
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10
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Ormsby TJR, Owens SE, Horlock AD, Davies D, Griffiths WJ, Wang Y, Cronin JG, Bromfield JJ, Sheldon IM. Oxysterols protect bovine endometrial cells against pore-forming toxins from pathogenic bacteria. FASEB J 2021; 35:e21889. [PMID: 34569656 PMCID: PMC9272411 DOI: 10.1096/fj.202100036r] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 06/16/2021] [Accepted: 08/16/2021] [Indexed: 11/11/2022]
Abstract
Many species of pathogenic bacteria secrete toxins that form pores in mammalian cell membranes. These membrane pores enable the delivery of virulence factors into cells, result in the leakage of molecules that bacteria can use as nutrients, and facilitate pathogen invasion. Inflammatory responses to bacteria are regulated by the side-chain-hydroxycholesterols 27-hydroxycholesterol and 25-hydroxycholesterol, but their effect on the intrinsic protection of cells against pore-forming toxins is unclear. Here, we tested the hypothesis that 27-hydroxycholesterol and 25-hydroxycholesterol help protect cells against pore-forming toxins. We treated bovine endometrial epithelial and stromal cells with 27-hydroxycholesterol or 25-hydroxycholesterol, and then challenged the cells with pyolysin, which is a cholesterol-dependent cytolysin from Trueperella pyogenes that targets these endometrial cells. We found that treatment with 27-hydroxycholesterol or 25-hydroxycholesterol protected both epithelial and stomal cells against pore formation and the damage caused by pyolysin. The oxysterols limited pyolysin-induced leakage of potassium and lactate dehydrogenase from cells, and reduced cytoskeletal changes and cytolysis. This oxysterol cytoprotection against pyolysin was partially dependent on reducing cytolysin-accessible cholesterol in the cell membrane and on activating liver X receptors. Treatment with 27-hydroxycholesterol also protected the endometrial cells against Staphylococcus aureus α-hemolysin. Using mass spectrometry, we found 27-hydroxycholesterol and 25-hydroxycholesterol in uterine and follicular fluid. Furthermore, epithelial cells released additional 25-hydroxycholesterol in response to pyolysin. In conclusion, both 27-hydroxycholesterol and 25-hydroxycholesterol increased the intrinsic protection of bovine endometrial cells against pore-forming toxins. Our findings imply that side-chain-hydroxycholesterols may help defend the endometrium against pathogenic bacteria.
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Affiliation(s)
| | - Sian E Owens
- Swansea University Medical School, Swansea University, Swansea, UK
| | | | - Daphne Davies
- Swansea University Medical School, Swansea University, Swansea, UK
| | | | - Yuqin Wang
- Swansea University Medical School, Swansea University, Swansea, UK
| | - James G Cronin
- Swansea University Medical School, Swansea University, Swansea, UK
| | - John J Bromfield
- Department of Animal Sciences, University of Florida, Gainesville, Florida, USA
| | - Iain M Sheldon
- Swansea University Medical School, Swansea University, Swansea, UK
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11
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Zaborowska M, Dziubak D, Matyszewska D, Bilewicz R. Surface and electrochemical properties of lipid raft model membranes and how they are affected by incorporation of statin. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.138514] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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12
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Why Do Tethered-Bilayer Lipid Membranes Suit for Functional Membrane Protein Reincorporation? APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11114876] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Membrane proteins (MPs) are essential for cellular functions. Understanding the functions of MPs is crucial as they constitute an important class of drug targets. However, MPs are a challenging class of biomolecules to analyze because they cannot be studied outside their native environment. Their structure, function and activity are highly dependent on the local lipid environment, and these properties are compromised when the protein does not reside in the cell membrane. Mammalian cell membranes are complex and composed of different lipid species. Model membranes have been developed to provide an adequate environment to envisage MP reconstitution. Among them, tethered-Bilayer Lipid Membranes (tBLMs) appear as the best model because they allow the lipid bilayer to be decoupled from the support. Thus, they provide a sufficient aqueous space to envisage the proper accommodation of large extra-membranous domains of MPs, extending outside. Additionally, as the bilayer remains attached to tethers covalently fixed to the solid support, they can be investigated by a wide variety of surface-sensitive analytical techniques. This review provides an overview of the different approaches developed over the last two decades to achieve sophisticated tBLMs, with a more and more complex lipid composition and adapted for functional MP reconstitution.
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13
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Bryant SJ, Garcia A, Clarke RJ, Warr GG. Selective ion transport across a lipid bilayer in a protic ionic liquid. SOFT MATTER 2021; 17:2688-2694. [PMID: 33533359 DOI: 10.1039/d0sm02225j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Ionic liquids (ILs) have exhibited enormous potential as electrolytes, designer solvents and reaction media, as well as being surprisingly effective platforms for amphiphile self-assembly and for preserving structure of complex biomolecules. This has led to their exploration as media for long-term biopreservation and in biosensors, for which their viability depends on their ability to sustain both structure and function within complex, multicomponent nanoscale compartments and assemblies. Here we show that a tethered lipid bilayer can be assembled directly in a purely IL environment that retains its structure upon exchange between IL and aqueous buffer, and that the membrane transporter valinomycin can be incorporated so as to retain its functionality and cation selectivity. This paves the way for the development of long-lived, non-aqueous microreactors and sensor assemblies, and demonstrates the potential for complex proteins to retain functionality in non-aqueous, ionic liquid solvents.
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Affiliation(s)
- Saffron J Bryant
- School of Chemistry, The University of Sydney, NSW 2006, Australia and School of Science, RMIT University, Melbourne, Victoria 3001, Australia.
| | - Alvaro Garcia
- School of Chemistry, The University of Sydney, NSW 2006, Australia and School of Life Sciences, University of Technology Sydney, NSW 2007, Australia
| | - Ronald J Clarke
- School of Chemistry, The University of Sydney, NSW 2006, Australia
| | - Gregory G Warr
- School of Chemistry, The University of Sydney, NSW 2006, Australia and University of Sydney Nano Institute, The University of Sydney, NSW 2006, Australia
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14
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Penkauskas T, Zentelyte A, Ganpule S, Valincius G, Preta G. Pleiotropic effects of statins via interaction with the lipid bilayer: A combined approach. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183306. [DOI: 10.1016/j.bbamem.2020.183306] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 03/18/2020] [Accepted: 04/07/2020] [Indexed: 12/25/2022]
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15
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Glutamine supports the protection of tissue cells against the damage caused by cholesterol-dependent cytolysins from pathogenic bacteria. PLoS One 2020; 15:e0219275. [PMID: 32163417 PMCID: PMC7067430 DOI: 10.1371/journal.pone.0219275] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 02/21/2020] [Indexed: 12/28/2022] Open
Abstract
Pathogenic bacteria often damage tissues by secreting toxins that form pores in cell membranes, and the most common pore-forming toxins are cholesterol-dependent cytolysins. During bacterial infections, glutamine becomes a conditionally essential amino acid, and glutamine is an important nutrient for immune cells. However, the role of glutamine in protecting tissue cells against pore-forming toxins is unclear. Here we tested the hypothesis that glutamine supports the protection of tissue cells against the damage caused by cholesterol-dependent cytolysins. Stromal and epithelial cells were sensitive to damage by the cholesterol-dependent cytolysins, pyolysin and streptolysin O, as determined by leakage of potassium and lactate dehydrogenase from cells, and reduced cell viability. However, glutamine deprivation increased the leakage of lactate dehydrogenase and reduced the viability of cells challenged with cholesterol-dependent cytolysins. Without glutamine, stromal cells challenged with pyolysin leaked lactate dehydrogenase (control vs. pyolysin, 2.6 ± 0.6 vs. 34.4 ± 4.5 AU, n = 12), which was more than three-fold the leakage from cells supplied with 2 mM glutamine (control vs. pyolysin, 2.2 ± 0.3 vs. 9.4 ± 1.0 AU). Glutamine cytoprotection did not depend on glutaminolysis, replenishing the Krebs cycle via succinate, changes in cellular cholesterol, or regulators of cell metabolism (AMPK and mTOR). In conclusion, although the mechanism remains elusive, we found that glutamine supports the protection of tissue cells against the damage caused by cholesterol-dependent cytolysins from pathogenic bacteria.
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16
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Griffin S, Healey GD, Sheldon IM. Isoprenoids increase bovine endometrial stromal cell tolerance to the cholesterol-dependent cytolysin from Trueperella pyogenes. Biol Reprod 2019; 99:749-760. [PMID: 29688258 PMCID: PMC6203874 DOI: 10.1093/biolre/ioy099] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 04/23/2018] [Indexed: 12/11/2022] Open
Abstract
Preventing postpartum uterine disease depends on the ability of endometrial cells to tolerate the presence of the bacteria that invade the uterus after parturition. Postpartum uterine disease and endometrial pathology in cattle are most associated with the pathogen Trueperella pyogenes. Trueperella pyogenes secretes a cholesterol-dependent cytolysin, pyolysin, which causes cytolysis by forming pores in the plasma membrane of endometrial stromal cells. The aim of the present study was to identify cell-intrinsic pathways that increase bovine endometrial stromal cell tolerance to pyolysin. Pyolysin caused dose-dependent cytolysis of bovine endometrial stromal cells and leakage of lactate dehydrogenase into supernatants. Cell tolerance to pyolysin was increased by inhibitors that target the mevalonate and cholesterol synthesis pathway, but not the mitogen-activated protein kinase, cell cycle, or metabolic pathways. Cellular cholesterol was reduced and cell tolerance to pyolysin was increased by supplying the mevalonate-derived isoprenoid farnesyl pyrophosphate, or by inhibiting farnesyl-diphosphate farnesyltransferase 1 or geranylgeranyl diphosphate synthase 1 to increase the abundance of farnesyl pyrophosphate. Supplying the mevalonate-derived isoprenoid geranylgeranyl pyrophosphate also increased cell tolerance to pyolysin, but independent of changes in cellular cholesterol. However, geranylgeranyl pyrophosphate inhibits nuclear receptor subfamily 1 group H receptors (NR1H, also known as liver X receptors), and reducing the expression of the genes encoding NR1H3 or NR1H2 increased stromal cell tolerance to pyolysin. In conclusion, mevalonate-derived isoprenoids increased bovine endometrial stromal cell tolerance to pyolysin, which was associated with reducing cellular cholesterol and inhibiting NR1H receptors.
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Affiliation(s)
- Sholeem Griffin
- Swansea University Medical School, Swansea University, Swansea, UK
| | - Gareth D Healey
- Swansea University Medical School, Swansea University, Swansea, UK
| | - I Martin Sheldon
- Swansea University Medical School, Swansea University, Swansea, UK
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Inerolysin and vaginolysin, the cytolysins implicated in vaginal dysbiosis, differently impair molecular integrity of phospholipid membranes. Sci Rep 2019; 9:10606. [PMID: 31337831 PMCID: PMC6650466 DOI: 10.1038/s41598-019-47043-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 07/09/2019] [Indexed: 02/07/2023] Open
Abstract
The pore-forming toxins, inerolysin (INY) and vaginolysin (VLY), produced by vaginal bacteria Lactobacillus iners and Gardnerella vaginalis were studied using the artificial cholesterol-rich tethered bilayer membranes (tBLMs) by electrochemical techniques. The electrochemical impedance spectroscopy (EIS) of tBLMs attested for the toxin-induced impairment of the integrity of phospholipid membranes. This observation was in line with the atomic force microscopy data demonstrating formation of oligomeric protein assemblies in tBLMs. These assemblies exhibited different morphologies: VLY mostly formed complete rings, whereas INY produced arciform structures. We found that both EIS (membrane damage) and the surface plasmon resonance (protein binding) data obtained on tBLMs are in-line with the data obtained in human cell lysis experiments. EIS, however, is capable of capturing effects inaccessible for biological activity assays. Specifically, we found that the INY-induced damage of tBLMs is nearly a linear function of membrane cholesterol content, whereas VLY triggered significant damage only at high (50 mol%) cholesterol concentrations. The observed differences of INY and VLY activities on phospholipid membranes might have clinical importance: both toxin-producing bacteria have been found in healthy vagina and dysbiosis, suggesting the need for adaptation at different vaginal conditions. Our results broaden the possibilities of application of tBLMs in medical diagnostics.
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Pathogenicity and Virulence of Trueperella pyogenes: A Review. Int J Mol Sci 2019; 20:ijms20112737. [PMID: 31167367 PMCID: PMC6600626 DOI: 10.3390/ijms20112737] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 05/31/2019] [Accepted: 05/31/2019] [Indexed: 12/19/2022] Open
Abstract
Bacteria from the species Trueperella pyogenes are a part of the biota of skin and mucous membranes of the upper respiratory, gastrointestinal, or urogenital tracts of animals, but also, opportunistic pathogens. T. pyogenes causes a variety of purulent infections, such as metritis, mastitis, pneumonia, and abscesses, which, in livestock breeding, generate significant economic losses. Although this species has been known for a long time, many questions concerning the mechanisms of infection pathogenesis, as well as reservoirs and routes of transmission of bacteria, remain poorly understood. Pyolysin is a major known virulence factor of T. pyogenes that belongs to the family of cholesterol-dependent cytolysins. Its cytolytic activity is associated with transmembrane pore formation. Other putative virulence factors, including neuraminidases, extracellular matrix-binding proteins, fimbriae, and biofilm formation ability, contribute to the adhesion and colonization of the host tissues. However, data about the pathogen–host interactions that may be involved in the development of T. pyogenes infection are still limited. The aim of this review is to present the current knowledge about the pathogenic potential and virulence of T. pyogenes.
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Penkauskas T, Preta G. Biological applications of tethered bilayer lipid membranes. Biochimie 2019; 157:131-141. [DOI: 10.1016/j.biochi.2018.11.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 11/19/2018] [Indexed: 12/16/2022]
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Gabriunaite I, Valiūnienė A, Valincius G. Formation and properties of phospholipid bilayers on fluorine doped tin oxide electrodes. Electrochim Acta 2018. [DOI: 10.1016/j.electacta.2018.04.160] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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21
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Santos AL, Preta G. Lipids in the cell: organisation regulates function. Cell Mol Life Sci 2018; 75:1909-1927. [PMID: 29427074 PMCID: PMC11105414 DOI: 10.1007/s00018-018-2765-4] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 01/04/2018] [Accepted: 01/29/2018] [Indexed: 12/19/2022]
Abstract
Lipids are fundamental building blocks of all cells and play important roles in the pathogenesis of different diseases, including inflammation, autoimmune disease, cancer, and neurodegeneration. The lipid composition of different organelles can vary substantially from cell to cell, but increasing evidence demonstrates that lipids become organised specifically in each compartment, and this organisation is essential for regulating cell function. For example, lipid microdomains in the plasma membrane, known as lipid rafts, are platforms for concentrating protein receptors and can influence intra-cellular signalling. Lipid organisation is tightly regulated and can be observed across different model organisms, including bacteria, yeast, Drosophila, and Caenorhabditis elegans, suggesting that lipid organisation is evolutionarily conserved. In this review, we summarise the importance and function of specific lipid domains in main cellular organelles and discuss recent advances that investigate how these specific and highly regulated structures contribute to diverse biological processes.
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Affiliation(s)
- Ana L Santos
- Institut National de la Santé et de la Recherche Médicale, U1001 and Faculté de Médecine, Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Giulio Preta
- Institute of Biochemistry, Vilnius University, Sauletekio 7, LT-10257, Vilnius, Lithuania.
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22
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Ragaliauskas T, Mickevicius M, Rakovska B, Penkauskas T, Vanderah DJ, Heinrich F, Valincius G. Fast formation of low-defect-density tethered bilayers by fusion of multilamellar vesicles. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:669-678. [PMID: 28088448 DOI: 10.1016/j.bbamem.2017.01.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/19/2016] [Accepted: 01/10/2017] [Indexed: 10/20/2022]
Abstract
A facile and reproducible preparation of surface-supported lipid bilayers is essential for fundamental membrane research and biotechnological applications. We demonstrate that multilamellar vesicles fuse to molecular-anchor-grafted surfaces yielding low-defect-density, tethered bilayer membranes. Continuous bilayers are formed within 10min, while the electrically insulating bilayers with <0.1μm-2 defect density can be accomplished within 60min. Surface plasmon resonance spectroscopy indicates that an amount of lipid material transferred from vesicles to a surface is inversely proportional to the density of an anchor, while the total amount of lipid that includes tethered and transferred lipid remains constant within 5% standard error. This attests for the formation of intact bilayers independent of the tethering agent density. Neutron reflectometry (NR) revealed the atomic level structural details of the tethered bilayer showing, among other things, that the total thickness of the hydrophobic slab of the construct was 3.2nm and that the molar fraction of cholesterol in lipid content is essentially the same as the molar fraction of cholesterol in the multilamellar liposomes. NR also indicated the formation of an overlayer with an effective thickness of 1.9nm. These overlayers may be easily removed by a single rinse of the tethered construct with 30% ethanol solution. Fast assembly and low residual defect density achievable within an hour of fusion makes our tethered bilayer methodology an attractive platform for biosensing of membrane damaging agents, such as pore forming toxins.
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Affiliation(s)
- Tadas Ragaliauskas
- Institute of Biochemistry, Vilnius University, Sauletekio 7, Vilnius LT-10257 , Lithuania
| | - Mindaugas Mickevicius
- Institute of Biochemistry, Vilnius University, Sauletekio 7, Vilnius LT-10257 , Lithuania
| | - Bozena Rakovska
- Institute of Biochemistry, Vilnius University, Sauletekio 7, Vilnius LT-10257 , Lithuania
| | - Tadas Penkauskas
- Institute of Biochemistry, Vilnius University, Sauletekio 7, Vilnius LT-10257 , Lithuania
| | - David J Vanderah
- Institute for Bioscience and Biotechnology Research, Rockville, MD 20850, USA
| | - Frank Heinrich
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA; Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Gintaras Valincius
- Institute of Biochemistry, Vilnius University, Sauletekio 7, Vilnius LT-10257 , Lithuania.
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23
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Valincius G, Mickevicius M, Penkauskas T, Jankunec M. Electrochemical Impedance Spectroscopy of Tethered Bilayer Membranes: An Effect of Heterogeneous Distribution of Defects in Membranes. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2016.11.056] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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