1
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Le Brun AP, Gilbert EP. Advances in sample environments for neutron scattering for colloid and interface science. Adv Colloid Interface Sci 2024; 327:103141. [PMID: 38631095 DOI: 10.1016/j.cis.2024.103141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 03/27/2024] [Accepted: 03/27/2024] [Indexed: 04/19/2024]
Abstract
This review describes recent advances in sample environments across the full complement of applicable neutron scattering techniques to colloid and interface science. Temperature, pressure, flow, tensile testing, ultrasound, chemical reactions, IR/visible/UV light, confinement, humidity and electric and magnetic field application, as well as tandem X-ray methods, are all addressed. Consideration for material choices in sample environments and data acquisition methods are also covered as well as discussion of current and potential future use of machine learning and artificial intelligence.
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Affiliation(s)
- Anton P Le Brun
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation (ANSTO), New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - Elliot Paul Gilbert
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation (ANSTO), New Illawarra Road, Lucas Heights, NSW 2234, Australia.
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2
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Caselli L, Nylander T, Malmsten M. Neutron reflectometry as a powerful tool to elucidate membrane interactions of drug delivery systems. Adv Colloid Interface Sci 2024; 325:103120. [PMID: 38428362 DOI: 10.1016/j.cis.2024.103120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 02/26/2024] [Accepted: 02/27/2024] [Indexed: 03/03/2024]
Abstract
The last couple of decades have seen an explosion of novel colloidal drug delivery systems, which have been demonstrated to increase drug efficacy, reduce side-effects, and provide various other advantages for both small-molecule and biomacromolecular drugs. The interactions of delivery systems with biomembranes are increasingly recognized to play a key role for efficient eradication of pathogens and cancer cells, as well as for intracellular delivery of protein and nucleic acid drugs. In parallel, there has been a broadening of methodologies for investigating such systems. For example, advanced microscopy, mass-spectroscopic "omic"-techniques, as well as small-angle X-ray and neutron scattering techniques, which only a few years ago were largely restricted to rather specialized areas within basic research, are currently seeing increased interest from researchers within wide application fields. In the present discussion, focus is placed on the use of neutron reflectometry to investigate membrane interactions of colloidal drug delivery systems. Although the technique is still less extensively employed for investigations of drug delivery systems than, e.g., X-ray scattering, such studies may provide key mechanistic information regarding membrane binding, re-modelling, translocation, and permeation, of key importance for efficacy and toxicity of antimicrobial, cancer, and other therapeutics. In the following, examples of this are discussed and gaps/opportunities in the research field identified.
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Affiliation(s)
| | - Tommy Nylander
- Physical Chemistry 1, Lund University, S-221 00 Lund, Sweden
| | - Martin Malmsten
- Physical Chemistry 1, Lund University, S-221 00 Lund, Sweden; Department of Pharmacy, University of Copenhagen, DK-2100 Copenhagen, Denmark.
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3
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Zubayer A, Ghafoor N, Thórarinsdóttir KA, Stendahl S, Glavic A, Stahn J, Nagy G, Greczynski G, Schwartzkopf M, Le Febvrier A, Eklund P, Birch J, Magnus F, Eriksson F. Reflective, polarizing, and magnetically soft amorphous neutron optics with 11B-enriched B 4C. SCIENCE ADVANCES 2024; 10:eadl0402. [PMID: 38354253 PMCID: PMC10866559 DOI: 10.1126/sciadv.adl0402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 01/12/2024] [Indexed: 02/16/2024]
Abstract
The utilization of polarized neutrons is of great importance in scientific disciplines spanning materials science, physics, biology, and chemistry. However, state-of-the-art multilayer polarizing neutron optics have limitations, particularly low specular reflectivity and polarization at higher scattering vectors/angles, and the requirement of high external magnetic fields to saturate the polarizer magnetization. Here, we show that, by incorporating 11B4C into Fe/Si multilayers, amorphization and smooth interfaces can be achieved, yielding higher neutron reflectivity, less diffuse scattering, and higher polarization. Magnetic coercivity is eliminated, and magnetic saturation can be reached at low external fields (>2 militesla). This approach offers prospects for substantial improvement in polarizing neutron optics with nonintrusive positioning of the polarizer, enhanced flux, increased data accuracy, and further polarizing/analyzing methods at neutron scattering facilities.
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Affiliation(s)
- Anton Zubayer
- Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
| | - Naureen Ghafoor
- Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
| | | | - Sjoerd Stendahl
- Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
| | - Artur Glavic
- Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Jochen Stahn
- Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Gyula Nagy
- Department of Physics and Astronomy, Uppsala University, SE-75120, Uppsala, Sweden
| | - Grzegorz Greczynski
- Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
| | | | - Arnaud Le Febvrier
- Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
| | - Per Eklund
- Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
| | - Jens Birch
- Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
| | - Fridrik Magnus
- Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik, Iceland
| | - Fredrik Eriksson
- Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
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4
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Stephani J, Gerhards L, Khairalla B, Solov’yov IA, Brand I. How do Antimicrobial Peptides Interact with the Outer Membrane of Gram-Negative Bacteria? Role of Lipopolysaccharides in Peptide Binding, Anchoring, and Penetration. ACS Infect Dis 2024; 10:763-778. [PMID: 38259029 PMCID: PMC10862549 DOI: 10.1021/acsinfecdis.3c00673] [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: 12/05/2023] [Revised: 12/31/2023] [Accepted: 01/02/2024] [Indexed: 01/24/2024]
Abstract
Gram-negative bacteria possess a complex structural cell envelope that constitutes a barrier for antimicrobial peptides that neutralize the microbes by disrupting their cell membranes. Computational and experimental approaches were used to study a model outer membrane interaction with an antimicrobial peptide, melittin. The investigated membrane included di[3-deoxy-d-manno-octulosonyl]-lipid A (KLA) in the outer leaflet and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) in the inner leaflet. Molecular dynamics simulations revealed that the positively charged helical C-terminus of melittin anchors rapidly into the hydrophilic headgroup region of KLA, while the flexible N-terminus makes contacts with the phosphate groups of KLA, supporting melittin penetration into the boundary between the hydrophilic and hydrophobic regions of the lipids. Electrochemical techniques confirmed the binding of melittin to the model membrane. To probe the peptide conformation and orientation during interaction with the membrane, polarization modulation infrared reflection absorption spectroscopy was used. The measurements revealed conformational changes in the peptide, accompanied by reorientation and translocation of the peptide at the membrane surface. The study suggests that melittin insertion into the outer membrane affects its permeability and capacitance but does not disturb the membrane's bilayer structure, indicating a distinct mechanism of the peptide action on the outer membrane of Gram-negative bacteria.
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Affiliation(s)
- Justus
C. Stephani
- Institute
of Physics, Carl von Ossietzky University
of Oldenburg, 26111 Oldenburg, Germany
| | - Luca Gerhards
- Institute
of Physics, Carl von Ossietzky University
of Oldenburg, 26111 Oldenburg, Germany
| | - Bishoy Khairalla
- Department
of Chemistry, Carl von Ossietzky University
of Oldenburg, 26111 Oldenburg, Germany
| | - Ilia A. Solov’yov
- Institute
of Physics, Carl von Ossietzky University
of Oldenburg, 26111 Oldenburg, Germany
- Research
Center Neurosensory Science, Carl von Ossietzky
University of Oldenburg, 26111 Oldenburg, Germany
- CeNaD—Center
for Nanoscale Dynamics, Carl von Ossietzky
University of Oldenburg, 26111 Oldenburg, Germany
| | - Izabella Brand
- Department
of Chemistry, Carl von Ossietzky University
of Oldenburg, 26111 Oldenburg, Germany
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5
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Lai X, Chow SH, Le Brun AP, Muir BW, Bergen PJ, White J, Yu HH, Wang J, Danne J, Jiang JH, Short FL, Han ML, Strugnell RA, Song J, Cameron NR, Peleg AY, Li J, Shen HH. Polysaccharide-Targeting Lipid Nanoparticles to Kill Gram-Negative Bacteria. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2305052. [PMID: 37798622 DOI: 10.1002/smll.202305052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 08/16/2023] [Indexed: 10/07/2023]
Abstract
The rapid increase and spread of Gram-negative bacteria resistant to many or all existing treatments threaten a return to the preantibiotic era. The presence of bacterial polysaccharides that impede the penetration of many antimicrobials and protect them from the innate immune system contributes to resistance and pathogenicity. No currently approved antibiotics target the polysaccharide regions of microbes. Here, describe monolaurin-based niosomes, the first lipid nanoparticles that can eliminate bacterial polysaccharides from hypervirulent Klebsiella pneumoniae, are described. Their combination with polymyxin B shows no cytotoxicity in vitro and is highly effective in combating K. pneumoniae infection in vivo. Comprehensive mechanistic studies have revealed that antimicrobial activity proceeds via a multimodal mechanism. Initially, lipid nanoparticles disrupt polysaccharides, then outer and inner membranes are destabilized and destroyed by polymyxin B, resulting in synergistic cell lysis. This novel lipidic nanoparticle system shows tremendous promise as a highly effective antimicrobial treatment targeting multidrug-resistant Gram-negative pathogens.
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Affiliation(s)
- Xiangfeng Lai
- Department of Materials Science and Engineering, Faculty of Engineering, Monash University, Clayton, Victoria, 3800, Australia
| | - Seong Hoong Chow
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, 3800, Australia
| | - Anton P Le Brun
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, New South Wales, 2232, Australia
| | | | - Phillip J Bergen
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Jacinta White
- CSIRO Manufacturing, Clayton, Victoria, 3168, Australia
| | - Heidi H Yu
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Jiping Wang
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Jill Danne
- Monash Ramaciotti Centre for Cryo-Electron Microscopy, A Node of Microscopy Australia, Monash University, Clayton, Victoria, 3800, Australia
| | - Jhih-Hang Jiang
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Francesca L Short
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Mei-Ling Han
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Richard A Strugnell
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, 3000, Australia
| | - Jiangning Song
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, 3800, Australia
| | - Neil R Cameron
- Department of Materials Science and Engineering, Faculty of Engineering, Monash University, Clayton, Victoria, 3800, Australia
| | - Anton Y Peleg
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Jian Li
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Hsin-Hui Shen
- Department of Materials Science and Engineering, Faculty of Engineering, Monash University, Clayton, Victoria, 3800, Australia
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
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6
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Hu X, Liao M, Ding K, Wang J, Xu H, Tao K, Zhou F, Lu JR. Neutron reflection and scattering in characterising peptide assemblies. Adv Colloid Interface Sci 2023; 322:103033. [PMID: 37931380 DOI: 10.1016/j.cis.2023.103033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 10/09/2023] [Accepted: 10/20/2023] [Indexed: 11/08/2023]
Abstract
Self-assemblies of de novo designed short peptides at interface and in bulk solution provide potential platforms for developing applications in many medical and technological areas. However, characterising how bioinspired supramolecular nanostructures evolve with dynamic self-assembling processes and respond to different stimuli remains challenging. Neutron scattering technologies including small angle neutron scattering (SANS) and neutron reflection (NR) can be advantageous and complementary to other state-of-the-art techniques in tracing structural changes under different conditions. With more neutron sources now available, SANS and NR are becoming increasingly popular in studying self-assembling processes of diverse peptide and protein systems, but the difficulty in experimental manipulation and data analysis can deter beginners. This review will introduce the basic theory, general experimental setup and data analysis of SANS and NR, followed by provision of their applications in characterising interfacial and solution self-assemblies of representative peptides and proteins. SANS and NR are remarkably effective in determining the morphological features self-assembled short peptides, especially size and shape transitions as a result of either sequence changes or in response to environmental stimuli, demonstrating the unique capability of NR and SANS in unravelling the interactive processes. These examples highlight the potential of NR and SANS in supporting the development of novel short peptides and proteins as biopharmaceutical candidates in the fight against many diseases and infections that share common features of membrane interactive processes.
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Affiliation(s)
- Xuzhi Hu
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK.; Lanzhou Institute of Chemical Physics, Tianshui Middle Road, Lanzhou 730000, Gansu, China
| | - Mingrui Liao
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Ke Ding
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Jiqian Wang
- Centre for Bioengineering and Biotechnology, College of Chemical Engineering, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao 266580, China
| | - Hai Xu
- Centre for Bioengineering and Biotechnology, College of Chemical Engineering, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao 266580, China
| | - Kai Tao
- State Key Laboratory of Fluid Power and Mechatronic Systems, Key Laboratory of Advanced Manufacturing Technology of Zhejiang Province, School of Mechanical Engineering, Zhejiang University, Hangzhou 310058, China; Zhejiang-Israel Joint Laboratory of Self-Assembling Functional Materials, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou 311215, China
| | - Feng Zhou
- Lanzhou Institute of Chemical Physics, Tianshui Middle Road, Lanzhou 730000, Gansu, China
| | - Jian R Lu
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK..
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7
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Clifton LA, Wacklin-Knecht HP, Ådén J, Mushtaq AU, Sparrman T, Gröbner G. Creation of distinctive Bax-lipid complexes at mitochondrial membrane surfaces drives pore formation to initiate apoptosis. SCIENCE ADVANCES 2023; 9:eadg7940. [PMID: 37267355 PMCID: PMC10413641 DOI: 10.1126/sciadv.adg7940] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 04/28/2023] [Indexed: 06/04/2023]
Abstract
Apotosis is an essential process tightly regulated by the Bcl-2 protein family where proapoptotic Bax triggers cell death by perforating the mitochondrial outer membrane. Although intensively studied, the molecular mechanism by which these proteins create apoptotic pores remains elusive. Here, we show that Bax creates pores by extracting lipids from outer mitochondrial membrane mimics by formation of Bax/lipid clusters that are deposited on the membrane surface. Time-resolved neutron reflectometry and Fourier transform infrared spectroscopy revealed two kinetically distinct phases in the pore formation process, both of which were critically dependent on cardiolipin levels. The initially fast adsorption of Bax on the mitochondrial membrane surface is followed by a slower formation of pores and Bax-lipid clusters on the membrane surface. Our findings provide a robust molecular understanding of mitochondrial membrane perforation by cell-killing Bax protein and illuminate the initial phases of programmed cellular death.
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Affiliation(s)
- Luke A. Clifton
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 OQX, UK
| | - Hanna P. Wacklin-Knecht
- European Spallation Source ERIC, ESS, P.O. Box 176, SE-22100 Lund, Sweden
- Department of Chemistry, Division of Physical Chemistry, Lund University, P.O. Box 124, SE-22100 Lund, Sweden
| | - Jörgen Ådén
- Department of Chemistry, University of Umeå, SE-90187 Umeå, Sweden
| | - Ameeq Ul Mushtaq
- Department of Chemistry, University of Umeå, SE-90187 Umeå, Sweden
| | - Tobias Sparrman
- Department of Chemistry, University of Umeå, SE-90187 Umeå, Sweden
| | - Gerhard Gröbner
- Department of Chemistry, University of Umeå, SE-90187 Umeå, Sweden
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8
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Nandi S, Nair KS, Bajaj H. Bacterial Outer-Membrane-Mimicking Giant Unilamellar Vesicle Model for Detecting Antimicrobial Permeability. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:5891-5900. [PMID: 37036429 DOI: 10.1021/acs.langmuir.3c00378] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The construction of bacterial outer membrane models with native lipids like lipopolysaccharide (LPS) is a barrier to understanding antimicrobial permeability at the membrane interface. Here, we engineer bacterial outer membrane (OM)-mimicking giant unilamellar vesicles (GUVs) by constituting LPS under different pH conditions and assembled GUVs with controlled dimensions. We quantify the LPS reconstituted in GUV membranes and reveal their arrangement in the leaflets of the vesicles. Importantly, we demonstrate the applications of OM vesicles by exploring antimicrobial permeability activity across membranes. Model peptides, melittin and magainin-2, are examined where both peptides exhibit lower membrane activity in OM vesicles than vesicles devoid of LPS. Our findings reveal the mode of action of antimicrobial peptides in bacterial-membrane-mimicking models. Notably, the critical peptide concentration required to elicit activity on model membranes correlates with the cell inhibitory concentrations that revalidate our models closely mimic bacterial membranes. In conclusion, we provide an OM-mimicking model capable of quantifying antimicrobial permeability across membranes.
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Affiliation(s)
- Samir Nandi
- Microbial Processes and Technology Division, CSIR- National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India
| | - Karthika S Nair
- Microbial Processes and Technology Division, CSIR- National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre, Ghaziabad 201002, India
| | - Harsha Bajaj
- Microbial Processes and Technology Division, CSIR- National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre, Ghaziabad 201002, India
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9
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Kinnun JJ, Scott HL, Bolmatov D, Collier CP, Charlton TR, Katsaras J. Biophysical studies of lipid nanodomains using different physical characterization techniques. Biophys J 2023; 122:931-949. [PMID: 36698312 PMCID: PMC10111277 DOI: 10.1016/j.bpj.2023.01.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 01/12/2023] [Accepted: 01/19/2023] [Indexed: 01/26/2023] Open
Abstract
For the past 50 years, evidence for the existence of functional lipid domains has been steadily accumulating. Although the notion of functional lipid domains, also known as "lipid rafts," is now widely accepted, this was not always the case. This ambiguity surrounding lipid domains could be partly attributed to the fact that they are highly dynamic, nanoscopic structures. Since most commonly used techniques are sensitive to microscale structural features, it is therefore, not surprising that it took some time to reach a consensus regarding their existence. In this review article, we will discuss studies that have used techniques that are inherently sensitive to nanoscopic structural features (i.e., neutron scatting, nuclear magnetic resonance, and Förster resonance energy transfer). We will also mention techniques that may be of use in the future (i.e., cryoelectron microscopy, droplet interface bilayers, inelastic x-ray scattering, and neutron reflectometry), which can further our understanding of the different and unique physicochemical properties of nanoscopic lipid domains.
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Affiliation(s)
- Jacob J Kinnun
- Large Scale Structures Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee; Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee.
| | - Haden L Scott
- Large Scale Structures Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee; Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - Dima Bolmatov
- Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee; Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee
| | - C Patrick Collier
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - Timothy R Charlton
- Large Scale Structures Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - John Katsaras
- Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee; Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee; Labs and Soft Matter Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee.
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10
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Arya SS, Morsy NK, Islayem DK, Alkhatib SA, Pitsalidis C, Pappa AM. Bacterial Membrane Mimetics: From Biosensing to Disease Prevention and Treatment. BIOSENSORS 2023; 13:bios13020189. [PMID: 36831955 PMCID: PMC9953710 DOI: 10.3390/bios13020189] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/19/2023] [Accepted: 01/24/2023] [Indexed: 05/31/2023]
Abstract
Plasma membrane mimetics can potentially play a vital role in drug discovery and immunotherapy owing to the versatility to assemble facilely cellular membranes on surfaces and/or nanoparticles, allowing for direct assessment of drug/membrane interactions. Recently, bacterial membranes (BMs) have found widespread applications in biomedical research as antibiotic resistance is on the rise, and bacteria-associated infections have become one of the major causes of death worldwide. Over the last decade, BM research has greatly benefited from parallel advancements in nanotechnology and bioelectronics, resulting in multifaceted systems for a variety of sensing and drug discovery applications. As such, BMs coated on electroactive surfaces are a particularly promising label-free platform to investigate interfacial phenomena, as well as interactions with drugs at the first point of contact: the bacterial membrane. Another common approach suggests the use of lipid-coated nanoparticles as a drug carrier system for therapies for infectious diseases and cancer. Herein, we discuss emerging platforms that make use of BMs for biosensing, bioimaging, drug delivery/discovery, and immunotherapy, focusing on bacterial infections and cancer. Further, we detail the synthesis and characteristics of BMs, followed by various models for utilizing them in biomedical applications. The key research areas required to augment the characteristics of bacterial membranes to facilitate wider applicability are also touched upon. Overall, this review provides an interdisciplinary approach to exploit the potential of BMs and current emerging technologies to generate novel solutions to unmet clinical needs.
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Affiliation(s)
- Sagar S. Arya
- Department of Biomedical Engineering, Khalifa University of Science and Technology, Abu Dhabi P.O. Box 127788, United Arab Emirates
| | - Nada K. Morsy
- Department of Biomedical Engineering, Khalifa University of Science and Technology, Abu Dhabi P.O. Box 127788, United Arab Emirates
| | - Deema K. Islayem
- Department of Biomedical Engineering, Khalifa University of Science and Technology, Abu Dhabi P.O. Box 127788, United Arab Emirates
| | - Sarah A. Alkhatib
- Department of Biomedical Engineering, Khalifa University of Science and Technology, Abu Dhabi P.O. Box 127788, United Arab Emirates
| | - Charalampos Pitsalidis
- Department of Physics Khalifa University of Science and Technology, Abu Dhabi P.O. Box 127788, United Arab Emirates
- Healthcare Engineering Innovation Center (HEIC), Khalifa University of Science and Technology, Abu Dhabi P.O. Box 127788, United Arab Emirates
- Department of Chemical Engineering and Biotechnology, Cambridge University, Philippa Fawcett Drive, Cambridge CB30AS, UK
| | - Anna-Maria Pappa
- Department of Biomedical Engineering, Khalifa University of Science and Technology, Abu Dhabi P.O. Box 127788, United Arab Emirates
- Healthcare Engineering Innovation Center (HEIC), Khalifa University of Science and Technology, Abu Dhabi P.O. Box 127788, United Arab Emirates
- Department of Chemical Engineering and Biotechnology, Cambridge University, Philippa Fawcett Drive, Cambridge CB30AS, UK
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11
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Newman KE, Khalid S. Conformational dynamics and putative substrate extrusion pathways of the N-glycosylated outer membrane factor CmeC from Campylobacter jejuni. PLoS Comput Biol 2023; 19:e1010841. [PMID: 36638139 PMCID: PMC9879487 DOI: 10.1371/journal.pcbi.1010841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 01/26/2023] [Accepted: 12/26/2022] [Indexed: 01/14/2023] Open
Abstract
The outer membrane factor CmeC of the efflux machinery CmeABC plays an important role in conferring antibiotic and bile resistance to Campylobacter jejuni. Curiously, the protein is N-glycosylated, with the glycans playing a key role in the effective function of this system. In this work we have employed atomistic equilibrium molecular dynamics simulations of CmeC in a representative model of the C. jejuni outer membrane to characterise the dynamics of the protein and its associated glycans. We show that the glycans are more conformationally labile than had previously been thought. The extracellular loops of CmeC visit the open and closed states freely suggesting the absence of a gating mechanism on this side, while the narrow periplasmic entrance remains tightly closed, regulated via coordination to solvated cations. We identify several cation binding sites on the interior surface of the protein. Additionally, we used steered molecular dynamics simulations to elucidate translocation pathways for a bile acid and a macrolide antibiotic. These, and additional equilibrium simulations suggest that the anionic bile acid utilises multivalent cations to climb the ladder of acidic residues that line the interior surface of the protein.
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Affiliation(s)
- Kahlan E. Newman
- School of Chemistry, University of Southampton, Southampton, United Kingdom
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton, United Kingdom
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
- * E-mail:
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12
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Charlton T, Guo EJ, Lavrik N, Fitzsimmons M. Liquid Helium as a reference may provide clarity for some neutron reflectometry experiments1. JOURNAL OF NEUTRON RESEARCH 2023. [DOI: 10.3233/jnr-220041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Neutron reflectometry experiments infer the variation of the scattering length density of a smooth planar film as a function of depth averaged over the lateral dimensions of the sample from the intensity of a neutron beam reflected by the sample. Because the phase information of the neutron wave function is not preserved by an intensity measurement, most analyses rely on comparisons of data to predictions from models. Such comparisons do not provide unique solutions and can yield erroneous conclusions. A real-world example is provided. We show that in some limited cases, measurements of a sample immersed in the vapor and liquid phases of Helium may improve model selection.
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Affiliation(s)
- T.C. Charlton
- Neutron Scattering Division, Oak Ridge National Lab, Oak Ridge, Tennessee, USA
| | - Er-Jia Guo
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - N. Lavrik
- Center for Nanophase Materials Sciences, Oak Ridge National Lab, Oak Ridge, Tennessee, USA
| | - M.R. Fitzsimmons
- Neutron Scattering Division, Oak Ridge National Lab, Oak Ridge, Tennessee, USA
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee, USA
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13
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Liao M, Gong H, Quan X, Wang Z, Hu X, Chen Z, Li Z, Liu H, Zhang L, McBain AJ, Waigh TA, Zhou J, Lu JR. Intramembrane Nanoaggregates of Antimicrobial Peptides Play a Vital Role in Bacterial Killing. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2204428. [PMID: 36417574 DOI: 10.1002/smll.202204428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 10/16/2022] [Indexed: 06/16/2023]
Abstract
Recent developments in antimicrobial peptides (AMPs) have focused on the rational design of short sequences with less than 20 amino acids due to their relatively low synthesis costs and ease of correlation of the structure-function relationship. However, gaps remain in the understanding of how short cationic AMPs interact with the bacterial outer and inner membranes to affect their antimicrobial efficacy and dynamic killing. The membrane-lytic actions of two designed AMPs, G(IIKK)3 I-NH2 (G3 ) and G(IIKK)4 I-NH2 (G4 ), and previously-studied controls GLLDLLKLLLKAAG-NH2 (LDKA, biomimetic) and GIGAVLKVLTTGLPALISWIKRKR-NH2 (Melittin, natural) are examined. The mechanistic processes of membrane damage and the disruption strength of the four AMPs are characterized by molecular dynamics simulations and experimental measurements including neutron reflection and scattering. The results from the combined studies are characterized with distinctly different intramembrane nanoaggregates formed upon AMP-specific binding, reflecting clear influences of AMP sequence, charge and the chemistry of the inner and outer membranes. G3 and G4 display different nanoaggregation with the outer and inner membranes, and the smaller sizes and further extent of insertion of the intramembrane nanoaggregates into bacterial membranes correlate well with their greater antimicrobial efficacy and faster dynamic killing. This work demonstrates the crucial roles of intramembrane nanoaggregates in optimizing antimicrobial efficacy and dynamic killing.
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Affiliation(s)
- Mingrui Liao
- Biological Physics Laboratory, Department of Physics and Astronomy, School of Natural Science, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Haoning Gong
- Biological Physics Laboratory, Department of Physics and Astronomy, School of Natural Science, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Xuebo Quan
- School of Chemistry and Chemical Engineering, Guangdong Provincial Key Laboratory for Green Chemical Product Technology, South China University of Technology, Guangzhou, 510640, China
| | - Ziwei Wang
- National Graphene Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Xuzhi Hu
- Biological Physics Laboratory, Department of Physics and Astronomy, School of Natural Science, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Zheng Chen
- School of Chemistry and Chemical Engineering, Guangdong Provincial Key Laboratory for Green Chemical Product Technology, South China University of Technology, Guangzhou, 510640, China
| | - Zongyi Li
- Biological Physics Laboratory, Department of Physics and Astronomy, School of Natural Science, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Huayang Liu
- Biological Physics Laboratory, Department of Physics and Astronomy, School of Natural Science, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Lin Zhang
- Biological Physics Laboratory, Department of Physics and Astronomy, School of Natural Science, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Andrew J McBain
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Thomas A Waigh
- Biological Physics Laboratory, Department of Physics and Astronomy, School of Natural Science, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Jian Zhou
- School of Chemistry and Chemical Engineering, Guangdong Provincial Key Laboratory for Green Chemical Product Technology, South China University of Technology, Guangzhou, 510640, China
| | - Jian Ren Lu
- Biological Physics Laboratory, Department of Physics and Astronomy, School of Natural Science, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
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14
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Webby MN, Oluwole AO, Pedebos C, Inns PG, Olerinyova A, Prakaash D, Housden NG, Benn G, Sun D, Hoogenboom BW, Kukura P, Mohammed S, Robinson CV, Khalid S, Kleanthous C. Lipids mediate supramolecular outer membrane protein assembly in bacteria. SCIENCE ADVANCES 2022; 8:eadc9566. [PMID: 36322653 PMCID: PMC9629720 DOI: 10.1126/sciadv.adc9566] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 09/13/2022] [Indexed: 06/16/2023]
Abstract
β Barrel outer membrane proteins (OMPs) cluster into supramolecular assemblies that give function to the outer membrane (OM) of Gram-negative bacteria. How such assemblies form is unknown. Here, through photoactivatable cross-linking into the Escherichia coli OM, coupled with simulations, and biochemical and biophysical analysis, we uncover the basis for OMP clustering in vivo. OMPs are typically surrounded by an annular shell of asymmetric lipids that mediate higher-order complexes with neighboring OMPs. OMP assemblies center on the abundant porins OmpF and OmpC, against which low-abundance monomeric β barrels, such as TonB-dependent transporters, are packed. Our study reveals OMP-lipid-OMP complexes to be the basic unit of supramolecular OMP assembly that, by extending across the entire cell surface, couples the requisite multifunctionality of the OM to its stability and impermeability.
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Affiliation(s)
- Melissa N. Webby
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
| | - Abraham O. Oluwole
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ, UK
- The Kavli Institute for Nanoscience Discovery, South Parks Road, Oxford OX1 3QZ, UK
| | - Conrado Pedebos
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
| | - Patrick G. Inns
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
| | - Anna Olerinyova
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ, UK
| | - Dheeraj Prakaash
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
| | - Nicholas G. Housden
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
| | - Georgina Benn
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
- Institute of Structural and Molecular Biology, University College London, London WC1E 6BT, UK
| | - Dawei Sun
- Structural Biology, Genentech Inc., South San Francisco, USA
| | - Bart W. Hoogenboom
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
- Institute of Structural and Molecular Biology, University College London, London WC1E 6BT, UK
- Department of Physics and Astronomy, University College London, WC1E 6BT London, UK
| | - Philipp Kukura
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ, UK
| | - Shabaz Mohammed
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford OX1 3QZ, UK
- Mechanistic Proteomics, Rosalind Franklin Institute, Harwell Campus, Didcot OX11 OFA, UK
| | - Carol V. Robinson
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ, UK
- The Kavli Institute for Nanoscience Discovery, South Parks Road, Oxford OX1 3QZ, UK
| | - Syma Khalid
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
| | - Colin Kleanthous
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
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15
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Vermaas JV, Crowley MF, Beckham GT. Molecular simulation of lignin-related aromatic compound permeation through gram-negative bacterial outer membranes. J Biol Chem 2022; 298:102627. [PMID: 36273587 PMCID: PMC9720347 DOI: 10.1016/j.jbc.2022.102627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 10/14/2022] [Accepted: 10/15/2022] [Indexed: 12/12/2022] Open
Abstract
Lignin, an abundant aromatic heteropolymer in secondary plant cell walls, is the single largest source of renewable aromatics in the biosphere. Leveraging this resource for renewable bioproducts through targeted microbial action depends on lignin fragment uptake by microbial hosts and subsequent enzymatic action to obtain the desired product. Recent computational work has emphasized that bacterial inner membranes are permeable to many aromatic compounds expected from lignin depolymerization processes. In this study, we expand on these findings through simulations for 42 lignin-related compounds across a gram-negative bacterial outer membrane model. Unbiased simulation trajectories indicate that spontaneous crossing for the full outer membrane is relatively rare at molecular simulation timescales, primarily due to preferential membrane partitioning and slow diffusion within the lipopolysaccharide layer within the outer membrane. Membrane partitioning and permeability coefficients were determined through replica exchange umbrella sampling simulations to overcome sampling limitations. We find that the glycosylated lipopolysaccharides found in the outer membrane increase the permeation barrier to many lignin-related compounds, particularly the most hydrophobic compounds. However, the effect is relatively modest; at industrially relevant concentrations, uncharged lignin-related compounds will readily diffuse across the outer membrane without the need for specific porins. Together, our results provide insight into the permeability of the bacterial outer membrane for assessing lignin fragment uptake and the future production of renewable bioproducts.
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Affiliation(s)
- Josh V. Vermaas
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA,National Center for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA,MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, Michigan, USA,Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA,For correspondence: Josh V. Vermaas; Michael F. Crowley; Gregg T. Beckham
| | - Michael F. Crowley
- Renewable Resources and Enabling Sciences Center, National Renewable Energy, Laboratory, Golden, Colorado, USA,For correspondence: Josh V. Vermaas; Michael F. Crowley; Gregg T. Beckham
| | - Gregg T. Beckham
- Renewable Resources and Enabling Sciences Center, National Renewable Energy, Laboratory, Golden, Colorado, USA,For correspondence: Josh V. Vermaas; Michael F. Crowley; Gregg T. Beckham
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16
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Li S, Ren R, Lyu L, Song J, Wang Y, Lin TW, Brun AL, Hsu HY, Shen HH. Solid and Liquid Surface-Supported Bacterial Membrane Mimetics as a Platform for the Functional and Structural Studies of Antimicrobials. MEMBRANES 2022; 12:membranes12100906. [PMID: 36295664 PMCID: PMC9609327 DOI: 10.3390/membranes12100906] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 09/05/2022] [Accepted: 09/13/2022] [Indexed: 06/02/2023]
Abstract
Increasing antibiotic resistance has provoked the urgent need to investigate the interactions of antimicrobials with bacterial membranes. The reasons for emerging antibiotic resistance and innovations in novel therapeutic approaches are highly relevant to the mechanistic interactions between antibiotics and membranes. Due to the dynamic nature, complex compositions, and small sizes of native bacterial membranes, bacterial membrane mimetics have been developed to allow for the in vitro examination of structures, properties, dynamics, and interactions. In this review, three types of model membranes are discussed: monolayers, supported lipid bilayers, and supported asymmetric bilayers; this review highlights their advantages and constraints. From monolayers to asymmetric bilayers, biomimetic bacterial membranes replicate various properties of real bacterial membranes. The typical synthetic methods for fabricating each model membrane are introduced. Depending on the properties of lipids and their biological relevance, various lipid compositions have been used to mimic bacterial membranes. For example, mixtures of phosphatidylethanolamines (PE), phosphatidylglycerols (PG), and cardiolipins (CL) at various molar ratios have been used, approaching actual lipid compositions of Gram-positive bacterial membranes and inner membranes of Gram-negative bacteria. Asymmetric lipid bilayers can be fabricated on solid supports to emulate Gram-negative bacterial outer membranes. To probe the properties of the model bacterial membranes and interactions with antimicrobials, three common characterization techniques, including quartz crystal microbalance with dissipation (QCM-D), surface plasmon resonance (SPR), and neutron reflectometry (NR) are detailed in this review article. Finally, we provide examples showing that the combination of bacterial membrane models and characterization techniques is capable of providing crucial information in the design of new antimicrobials that combat bacterial resistance.
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Affiliation(s)
- Shiqi Li
- Department of Materials Science and Engineering, Faculty of Engineering, Monash University, Clayton, VIC 3800, Australia
| | - Ruohua Ren
- Department of Materials Science and Engineering, Faculty of Engineering, Monash University, Clayton, VIC 3800, Australia
| | - Letian Lyu
- Department of Materials Science and Engineering, Faculty of Engineering, Monash University, Clayton, VIC 3800, Australia
| | - Jiangning Song
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Yajun Wang
- College of Chemistry & Materials Engineering, Wenzhou University, Wenzhou 325035, China
| | - Tsung-Wu Lin
- Department of Chemistry, Tunghai University, No. 1727, Sec. 4, Taiwan Boulevard, Xitun District, Taichung 40704, Taiwan
| | - Anton Le Brun
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Hsien-Yi Hsu
- Department of Materials Science and Engineering, School of Energy and Environment, City University of Hong Kong, Kowloon Tong, Hong Kong, China
| | - Hsin-Hui Shen
- Department of Materials Science and Engineering, Faculty of Engineering, Monash University, Clayton, VIC 3800, Australia
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
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17
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Lamichhane TN, Charlton TR, Andrews B, Malaviya D, Pathak AK, Ambaye H, Doucet M, Lauter V, Katsaras J, Post BK, Paranthaman MP. Additively Manufactured NdFeB Polyphenylene Sulfide Halbach Magnets to Generate Variable Magnetic Fields for Neutron Reflectometry. 3D PRINTING AND ADDITIVE MANUFACTURING 2022; 9:245-254. [PMID: 36654742 PMCID: PMC9831552 DOI: 10.1089/3dp.2020.0340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Halbach arrays are the most efficient closed structures for generating directed magnetic fields and gradients, and are widely used in various electric machines. We utilized fused deposition modeling-based Big Area Additive Manufacturing technology to print customized, compensated concentric Halbach array rings, using polyphenylene sulfide-bonded NdFeB permanent magnets for polarized neutron reflectometry. The Halbach rings could generate a 0 ≤ B ≤ 0.30 T field, while preserving 90% polarization of an axial neutron beam. Polarized neutron beams are used to study a wide range of structural and magnetic phenomena spanning physics, chemistry, and biology. In this study, we demonstrate the effectiveness of additive manufacturing for producing prototype Halbach arrays, characterize their magnetic properties, and generated magnetic fields, and discuss the conservation of neutron beam polarization as a function of magnetic field.
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Affiliation(s)
- Tej Nath Lamichhane
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Timothy R. Charlton
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Brian Andrews
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Devanshi Malaviya
- Department of Physics, Buffalo State, The State University of New York (SUNY), Buffalo, New York, USA
| | - Arjun K. Pathak
- Department of Physics, Buffalo State, The State University of New York (SUNY), Buffalo, New York, USA
| | - Haile Ambaye
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Mathieu Doucet
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Valeria Lauter
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - John Katsaras
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
- Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee, USA
| | - Brian K. Post
- Manufacturing Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
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18
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Durant JH, Wilkins L, Cooper JFK. Optimizing experimental design in neutron reflectometry. J Appl Crystallogr 2022; 55:769-781. [PMID: 35974737 PMCID: PMC9348865 DOI: 10.1107/s1600576722003831] [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: 08/12/2021] [Accepted: 04/06/2022] [Indexed: 11/26/2022] Open
Abstract
An approach for optimal experimental design of neutron reflectivity experiments using metrics derived from the Fisher information is presented. This is demonstrated on a range of systems including lipid bilayers and magnetic heterostructures, and it is shown that small (or large) changes to the experimental setup can result in drastically reduced experimental count times. Using the Fisher information (FI), the design of neutron reflectometry experiments can be optimized, leading to greater confidence in parameters of interest and better use of experimental time [Durant, Wilkins, Butler & Cooper (2021). J. Appl. Cryst.54, 1100–1110]. In this work, the FI is utilized in optimizing the design of a wide range of reflectometry experiments. Two lipid bilayer systems are investigated to determine the optimal choice of measurement angles and liquid contrasts, in addition to the ratio of the total counting time that should be spent measuring each condition. The reduction in parameter uncertainties with the addition of underlayers to these systems is then quantified, using the FI, and validated through the use of experiment simulation and Bayesian sampling methods. For a ‘one-shot’ measurement of a degrading lipid monolayer, it is shown that the common practice of measuring null-reflecting water is indeed optimal, but that the optimal measurement angle is dependent on the deuteration state of the monolayer. Finally, the framework is used to demonstrate the feasibility of measuring magnetic signals as small as 0.01 μB per atom in layers only 20 Å thick, given the appropriate experimental design, and that the time to reach a given level of confidence in the small magnetic moment is quantifiable.
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19
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Lakey JH, Paracini N, Clifton LA. Exploiting neutron scattering contrast variation in biological membrane studies. BIOPHYSICS REVIEWS 2022; 3:021307. [PMID: 38505417 PMCID: PMC10903484 DOI: 10.1063/5.0091372] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 05/03/2022] [Indexed: 03/21/2024]
Abstract
Biological membranes composed of lipids and proteins are central for the function of all cells and individual components, such as proteins, that are readily studied by a range of structural approaches, including x-ray crystallography and cryo-electron microscopy. However, the study of complex molecular mixtures within the biological membrane structure and dynamics requires techniques that can study nanometer thick molecular bilayers in an aqueous environment at ambient temperature and pressure. Neutron methods, including scattering and spectroscopic approaches, are useful since they can measure structure and dynamics while also being able to penetrate sample holders and cuvettes. The structural approaches, such as small angle neutron scattering and neutron reflectometry, detect scattering caused by the difference in neutron contrast (scattering length) between different molecular components such as lipids or proteins. Usually, the bigger the contrast, the clearer the structural data, and this review uses examples from our research to illustrate how contrast can be increased to allow the structures of individual membrane components to be resolved. Most often this relies upon the use of deuterium in place of hydrogen, but we also discuss the use of magnetic contrast and other elements with useful scattering length values.
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Affiliation(s)
- Jeremy H. Lakey
- Institute for Cell and Molecular Bioscience, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Nicolò Paracini
- Biofilms Research Center for Biointerfaces, Malmö University, Per Albin Hanssons väg 35, 21432 Malmö, Sweden
| | - Luke A. Clifton
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
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20
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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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21
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Paracini N, Schneck E, Imberty A, Micciulla S. Lipopolysaccharides at Solid and Liquid Interfaces: Models for Biophysical Studies of the Gram-negative Bacterial Outer Membrane. Adv Colloid Interface Sci 2022; 301:102603. [PMID: 35093846 DOI: 10.1016/j.cis.2022.102603] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 01/14/2022] [Accepted: 01/15/2022] [Indexed: 11/18/2022]
Abstract
Lipopolysaccharides (LPSs) are a constitutive element of the cell envelope of Gram-negative bacteria, representing the main lipid in the external leaflet of their outer membrane (OM) lipid bilayer. These unique surface-exposed glycolipids play a central role in the interactions of Gram-negative organisms with their surrounding environment and represent a key element for protection against antimicrobials and the development of antibiotic resistance. The biophysical investigation of a wide range of different types of in vitro model membranes containing reconstituted LPS has revealed functional and structural properties of these peculiar membrane lipids, providing molecular-level details of their interaction with antimicrobial compounds. LPS assemblies reconstituted at interfaces represent a versatile tool to study the properties of the Gram-negative OM by exploiting several surface-sensitive techniques, in particular X-ray and neutron scattering, which can probe the structure of thin films with sub-nanometer resolution. This review provides an overview of different approaches employed to investigate structural and biophysical properties of LPS, focusing on studies on Langmuir monolayers of LPS at the air/liquid interface and a range of supported LPS-containing model membranes reconstituted at solid/liquid interfaces.
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Affiliation(s)
| | - Emanuel Schneck
- Physics Departent, Technische Universität Darmstadt, Darmstadt, Germany
| | - Anne Imberty
- Université Grenoble Alpes, CNRS, CERMAV, Grenoble, France
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22
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Lai X, Han ML, Ding Y, Chow SH, Le Brun AP, Wu CM, Bergen PJ, Jiang JH, Hsu HY, Muir BW, White J, Song J, Li J, Shen HH. A polytherapy based approach to combat antimicrobial resistance using cubosomes. Nat Commun 2022; 13:343. [PMID: 35039508 PMCID: PMC8763928 DOI: 10.1038/s41467-022-28012-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 12/07/2021] [Indexed: 12/21/2022] Open
Abstract
A depleted antimicrobial drug pipeline combined with an increasing prevalence of Gram-negative ‘superbugs’ has increased interest in nano therapies to treat antibiotic resistance. As cubosomes and polymyxins disrupt the outer membrane of Gram-negative bacteria via different mechanisms, we herein examine the antimicrobial activity of polymyxin-loaded cubosomes and explore an alternative strategy via the polytherapy treatment of pathogens with cubosomes in combination with polymyxin. The polytherapy treatment substantially increases antimicrobial activity compared to polymyxin B-loaded cubosomes or polymyxin and cubosomes alone. Confocal microscopy and neutron reflectometry suggest the superior polytherapy activity is achieved via a two-step process. Firstly, electrostatic interactions between polymyxin and lipid A initially destabilize the outer membrane. Subsequently, an influx of cubosomes results in further membrane disruption via a lipid exchange process. These findings demonstrate that nanoparticle-based polytherapy treatments may potentially serve as improved alternatives to the conventional use of drug-loaded lipid nanoparticles for the treatment of “superbugs”. An increasing prevalence of Gram-negative bacteria increases the interest in nanotherapies to treat antibiotic resistance. Here, the authors examine the antimicrobial activity of polymyxin-loaded cubosomes and explore a polytherapy treatment of pathogens with cubosomes in combination with polymyxin.
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Affiliation(s)
- Xiangfeng Lai
- Department of Materials Science and Engineering, Faculty of Engineering, Monash University, Clayton, VIC, 3800, Australia
| | - Mei-Ling Han
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC, 3800, Australia
| | - Yue Ding
- Department of Materials Science and Engineering, Faculty of Engineering, Monash University, Clayton, VIC, 3800, Australia.,Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, 3800, Australia
| | - Seong Hoong Chow
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, 3800, Australia
| | - Anton P Le Brun
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Chun-Ming Wu
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia.,National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - Phillip J Bergen
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC, 3800, Australia
| | - Jhih-Hang Jiang
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC, 3800, Australia
| | - Hsien-Yi Hsu
- School of Energy and Environment & Department of Materials Science and Engineering, City University of Hong Kong, Kowloon Tong, Hong Kong, China.,Shenzhen Research Institute of City University of Hong Kong, 518057, Shenzhen, China
| | | | | | - Jiangning Song
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, 3800, Australia
| | - Jian Li
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC, 3800, Australia.
| | - Hsin-Hui Shen
- Department of Materials Science and Engineering, Faculty of Engineering, Monash University, Clayton, VIC, 3800, Australia. .,Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, 3800, Australia.
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23
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Khairalla B, Brand I. Membrane Potentials Trigger Molecular-Scale Rearrangements in the Outer Membrane of Gram-Negative Bacteria. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:446-457. [PMID: 34963050 DOI: 10.1021/acs.langmuir.1c02820] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The structural complexity of the cell envelope of Gram-negative bacteria limits the fabrication of realistic models of bacterial cell membranes. A vertical Langmuir-Blodgett withdrawing was used to deposit a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) monolayer on the Au(111) surface. The second leaflet composed of di[3-deoxy-D-manno-octulosonyl]-lipid A (KLA) was deposited using Langmuir-Schaefer transfer. The use of an electrode material as a support for the POPE-KLA bilayer allowed electrochemical control of the membrane's stability, compactness, and structure. Capacitance-potential curves showed a typical pattern for the supported lipid bilayers electrochemical characteristic. The minimum membrane capacitance was ∼4 μF cm-2 and did not change in the following desorption-adsorption cycles, indicating the presence of a stable bilayer structure with an asymmetric composition of both leaflets. However, at a molecular scale, as elucidated in spectroelectrochemical experiments, large differences in the response of both leaflets to electric potentials were observed. The acyl chains in POPE and KLA existed in a liquid state. The quantitative analysis of the CH stretching modes indicated potential-driven reorientations in the hydrophobic fragment of the bilayer, already in the adsorbed state. To assign observed rearrangements to POPE and KLA lipids in both leaflets, per-deuterated d31-POPE was transferred into the inner leaflet. Since no potential-dependent changes of the CD2 stretching modes in the d31-POPE-KLA bilayer were observed, reorientations in the acyl chain region were assigned to the KLA molecules. Mg2+ ions were bound to the polar head groups of KLA. The strength of electrostatic interactions in the polar head group region of KLA was dependent on the direction of the electric field. At negative electric potentials, the binding of divalent cations weakened, which gave the KLA molecules increased orientational flexibility. This behavior in electric fields is peculiar for the outer membrane and indicates that the microbial cell membranes have different electrochemical properties than phospholipid bilayers.
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Affiliation(s)
- Bishoy Khairalla
- Department of Chemistry, University of Oldenburg, 26111 Oldenburg, Germany
| | - Izabella Brand
- Department of Chemistry, University of Oldenburg, 26111 Oldenburg, Germany
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Wang Z, Zheng Y, Ji M, Zhang X, Wang H, Chen Y, Wu Q, Chen GQ. Hyperproduction of PHA copolymers containing high fractions of 4-hydroxybutyrate (4HB) by outer membrane-defected Halomonas bluephagenesis grown in bioreactors. Microb Biotechnol 2022; 15:1586-1597. [PMID: 34978757 PMCID: PMC9049619 DOI: 10.1111/1751-7915.13999] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 12/16/2021] [Accepted: 12/17/2021] [Indexed: 01/07/2023] Open
Abstract
Bacterial outer membrane (OM) is a self‐protective and permeable barrier, while having many non‐negligible negative effects in industrial biotechnology. Our previous studies revealed enhanced properties of Halomonas bluephagenesis based on positive cellular properties by OM defects. This study further expands the OM defect on membrane compactness by completely deleting two secondary acyltransferases for lipid A modification in H. bluephagenesis, LpxL and LpxM, and found more significant advantages than that of the previous lpxL mutant. Deletions on LpxL and LpxM accelerated poly(3‐hydroxybutyrate) (PHB) production by H. bluephagenesis WZY229, leading to a 37% increase in PHB accumulation and 84‐folds reduced endotoxin production. Enhanced membrane permeability accelerates the diffusion of γ‐butyrolactone, allowing H. bluephagenesis WZY254 derived from H. bluephagenesis WZY229 to produce 82wt% poly(3‐hydroxybutyrate‐co‐23mol%4‐hydroxybutyrate) (P(3HB‐co‐23mol%4HB)) in shake flasks, showing increases of 102% and 307% in P(3HB‐co‐4HB) production and 4HB accumulation, respectively. The 4HB molar fraction in copolymer can be elevated to 32 mol% in the presence of more γ‐butyrolactone. In a 7‐l bioreactor fed‐batch fermentation, H. bluephagenesis WZY254 supported a 84 g l−1 dry cell mass with 81wt% P(3HB‐co‐26mol%4HB), increasing 136% in 4HB molar fraction. This study further demonstrated that OM defects generate a hyperproduction strain for high 4HB containing copolymers.
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Affiliation(s)
- Ziyu Wang
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yifei Zheng
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Mengke Ji
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Xu Zhang
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Huan Wang
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yuemeng Chen
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Qiong Wu
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Guo-Qiang Chen
- School of Life Sciences, Tsinghua University, Beijing, 100084, China.,Center for Synthetic and Systems Biology, Tsinghua University, Beijing, 100084, China.,Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China.,MOE Key Lab of Industrial Biocatalysis, Dept Chemical Engineering, Tsinghua University, Beijing, 100084, China
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25
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Sun Y, Deng Z, Jiang X, Yuan B, Yang K. Interactions between polymyxin B and various bacterial membrane mimics: A molecular dynamics study. Colloids Surf B Biointerfaces 2021; 211:112288. [PMID: 34942463 DOI: 10.1016/j.colsurfb.2021.112288] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 11/21/2021] [Accepted: 12/11/2021] [Indexed: 11/17/2022]
Abstract
Polymyxin B (PMB) is clinically used as a last-line therapy against life-threatening Gram-negative "superbugs". However, thorough understanding of the membrane actions of PMB at a molecular level is still lacking. In this work, a variety of bacterial membrane mimics with varying lipid compositions were built, and their interactions with PMB were systematically investigated using coarse-grained molecular dynamics simulation. PMB demonstrated characteristic preference to specific lipid species during its interaction with different membrane systems, such as the rough mutant lipipolysacchrides (Re LPS) preference in an outer membrane (OM) or the cardiolipin and POPG affinity in an inner membrane (IM). As a result of the lipid-specific actions, complicated membrane interaction states of PMB were observed, including adsorption on the OM surface. In contrast, for the IM or a mutative OM containing "impurity lipids" like POPE, POPG or lipid A, it could insert into the membrane via its acyl chain. Such actions of PMB influence the structure and lipid mobility of the membrane. In particular, the OM-bound PMB breaks the synchronous movement of Re LPS molecules in the outer leaflet and makes them diffuse more randomly, while its insertion into IM blocks the phospholipid diffusion and makes the membrane more homogeneous in the trajectory space. Our results provide insight into the action mechanism of PMB at a membrane level and a foundation for developing novel and safer polymyxin strategies for better clinical use.
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Affiliation(s)
- Yuliang Sun
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou 215006, Jiangsu, China
| | - Zhixiong Deng
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou 215006, Jiangsu, China
| | - Xukai Jiang
- National Glycoengineering Research Center, Shandong University, Qingdao 266237, Shandong, China
| | - Bing Yuan
- Songshan Lake Materials Laboratory, Dongguan 523808, Guangdong, China.
| | - Kai Yang
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou 215006, Jiangsu, China.
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26
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Hall SCL, Clifton LA, Sridhar P, Hardy DJ, Wotherspoon P, Wright J, Whitehouse J, Gamage N, Laxton CS, Hatton C, Hughes GW, Jeeves M, Knowles TJ. Surface-tethered planar membranes containing the β-barrel assembly machinery: a platform for investigating bacterial outer membrane protein folding. Biophys J 2021; 120:5295-5308. [PMID: 34757080 PMCID: PMC8715194 DOI: 10.1016/j.bpj.2021.10.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 09/06/2021] [Accepted: 10/26/2021] [Indexed: 11/16/2022] Open
Abstract
The outer membrane of Gram-negative bacteria presents a robust physicochemical barrier protecting the cell from both the natural environment and acting as the first line of defense against antimicrobial materials. The proteins situated within the outer membrane are responsible for a range of biological functions including controlling influx and efflux. These outer membrane proteins (OMPs) are ultimately inserted and folded within the membrane by the β-barrel assembly machine (Bam) complex. The precise mechanism by which the Bam complex folds and inserts OMPs remains unclear. Here, we have developed a platform for investigating Bam-mediated OMP insertion. By derivatizing a gold surface with a copper-chelating self-assembled monolayer, we were able to assemble a planar system containing the complete Bam complex reconstituted within a phospholipid bilayer. Structural characterization of this interfacial protein-tethered bilayer by polarized neutron reflectometry revealed distinct regions consistent with known high-resolution models of the Bam complex. Additionally, by monitoring changes of mass associated with OMP insertion by quartz crystal microbalance with dissipation monitoring, we were able to demonstrate the functionality of this system by inserting two diverse OMPs within the membrane, pertactin, and OmpT. This platform has promising application in investigating the mechanism of Bam-mediated OMP insertion, in addition to OMP function and activity within a phospholipid bilayer environment.
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Affiliation(s)
- Stephen C L Hall
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Oxfordshire, United Kingdom
| | - Luke A Clifton
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Oxfordshire, United Kingdom
| | - Pooja Sridhar
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - David J Hardy
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Peter Wotherspoon
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Jack Wright
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - James Whitehouse
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Nadisha Gamage
- Membrane Protein Laboratory, Diamond Light Source, Harwell Science & Innovation Campus, Oxfordshire, United Kingdom
| | - Claire S Laxton
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Caitlin Hatton
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Gareth W Hughes
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Mark Jeeves
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Timothy J Knowles
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom.
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27
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Mohamed Z, Shin JH, Ghosh S, Sharma AK, Pinnock F, Bint E Naser Farnush S, Dörr T, Daniel S. Clinically Relevant Bacterial Outer Membrane Models for Antibiotic Screening Applications. ACS Infect Dis 2021; 7:2707-2722. [PMID: 34227387 DOI: 10.1021/acsinfecdis.1c00217] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Antibiotic resistance is a growing global health concern that has been increasing in prevalence over the past few decades. In Gram-negative bacteria, the outer membrane is an additional barrier through which antibiotics must traverse to kill the bacterium. In addition, outer membrane features and properties, like membrane surface charge, lipopolysaccharide (LPS) length, and membrane porins, can be altered in response to antibiotics and therefore, further mediate resistance. Model membranes have been used to mimic bacterial membranes to study antibiotic-induced membrane changes but often lack the compositional complexity of the actual outer membrane. Here, we developed a surface-supported membrane platform using outer membrane vesicles (OMVs) from clinically relevant Gram-negative bacteria and use it to characterize membrane biophysical properties and investigate its interaction with antibacterial compounds. We demonstrate that this platform maintains critical features of outer membranes, like fluidity, while retaining complex membrane components, like OMPs and LPS, which are central to membrane-mediated antibiotic resistance. This platform offers a non-pathogenic, cell-free surface to study such phenomena that is compatible with advanced microscopy and surface characterization tools like quartz crystal microbalance. We confirm these OMV bilayers recapitulate membrane interactions (or lack thereof) with the antibiotic compounds polymyxin B, bacitracin, and vancomycin, validating their use as representative models for the bacterial surface. By forming OMV bilayers from different strains, we envision that this platform could be used to investigate underlying biophysical differences in outer membranes leading to resistance, to screen and identify membrane-active antibiotics, or for the development of phage technologies targeting a particular membrane surface component.
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Affiliation(s)
- Zeinab Mohamed
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York United States
| | - Jung-Ho Shin
- Weill Institute for Cell and Molecular Biology and Department of Microbiology, Cornell University, Ithaca, New York United States
| | - Surajit Ghosh
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York United States
| | - Abhishek K. Sharma
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York United States
| | - Ferra Pinnock
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York United States
| | - Samavi Bint E Naser Farnush
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York United States
| | - Tobias Dörr
- Weill Institute for Cell and Molecular Biology and Department of Microbiology, Cornell University, Ithaca, New York United States
| | - Susan Daniel
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York United States
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York United States
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28
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John LH, Preston GM, Sansom MSP, Clifton LA. Large scale model lipid membrane movement induced by a cation switch. J Colloid Interface Sci 2021; 596:297-311. [PMID: 33839355 PMCID: PMC8109235 DOI: 10.1016/j.jcis.2021.03.078] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 03/11/2021] [Accepted: 03/13/2021] [Indexed: 11/25/2022]
Abstract
A biomembrane sample system where millimolar changes of cations induce reversible large scale (≥ 200 Å) changes in the membrane-to-surface distance is described. The system composes of a free-floating bilayer, formed adjacent to a self-assembled monolayer (SAM). To examine the membrane movements, differently charged floating bilayers in the presence and absence of Ca2+ and Na+, respectively, were examined using neutron reflectivity and quartz crystal microbalance measurements, alongside molecular dynamics simulations. In neutron reflectivity the variation of Ca2+ and Na+ concentration enabled precision manipulation of the membrane-to-surface distance. Simulations suggest that Ca2+ ions bridge between SAM and bilayer whereas the more diffuse binding of Na+, especially to bilayers, is unable to fully overcome the repulsion between anionic floating bilayer and anionic SAM. Reproduced neutron reflectivity results with quartz crystal microbalance demonstrate the potential of this easily producible sample system to become a standard analysis tool for e.g. investigating membrane binding effects, endocytosis and cell signaling.
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Affiliation(s)
- Laura H John
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK; ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 OQX, UK
| | - Gail M Preston
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Luke A Clifton
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 OQX, UK.
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29
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Nourbakhsh S, Yu L, Ha BY. Modeling the Protective Role of Bacterial Lipopolysaccharides against Membrane-Rupturing Peptides. J Phys Chem B 2021; 125:8839-8854. [PMID: 34319722 DOI: 10.1021/acs.jpcb.1c02330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Lipopolysaccharide (LPS) is a key surface component of Gram-negative bacteria, populating the outer layer of their outer membrane. A number of experimental studies highlight its protective role against harmful molecules such as antibiotics and antimicrobial peptides (AMPs). In this work, we present a theoretical model for describing the interaction between LPS and cationic antimicrobial peptides, which combines the following two key features. The polysaccharide part is viewed as forming a polymer brush, exerting an osmotic pressure on inclusions such as antimicrobial peptides. The charged groups on LPS (those in lipid A and the two Kdo groups in the inner core) form electrostatic binding sites for cationic AMPs or cations. Using the resulting model, we offer a quantitative picture of how the brush component enhances the protective role of LPS against magainin-like peptides, in the presence of divalent cations such as Mg2+. The LPS brush tends to diminish the interfacial binding of the peptides, at the lipid headgroup region, by about 30%. In the presence of 5 mM of Mg2+, the interfacial binding does not reach a threshold value for wild-type LPS, beyond which the LPS layer is ruptured, even though it does for LPS Re (the simplest form of LPS, lacking the brush part), as long as [AMP] ≤ 20 μM, where [AMP] is the concentration of AMPs. At a low concentration of Mg2+ (≈1 mM), however, a smaller [AMP] value (≳2 μM) is needed to reach the threshold coverage for wild-type LPS. Our results also suggest that the interfacial binding of peptides is insensitive to their possible weak interaction with the surrounding brush chains.
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Affiliation(s)
- Shokoofeh Nourbakhsh
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Liu Yu
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Bae-Yeun Ha
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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30
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Studying the surfaces of bacteria using neutron scattering: finding new openings for antibiotics. Biochem Soc Trans 2021; 48:2139-2149. [PMID: 33005925 PMCID: PMC7609035 DOI: 10.1042/bst20200320] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/26/2020] [Accepted: 09/01/2020] [Indexed: 12/29/2022]
Abstract
The use of neutrons as a scattering probe to investigate biological membranes has steadily grown in the past three decades, shedding light on the structure and behaviour of this ubiquitous and fundamental biological barrier. Meanwhile, the rise of antibiotic resistance has catalysed a renewed interest in understanding the mechanisms underlying the dynamics of antibiotics interaction with the bacterial cell envelope. It is widely recognised that the key reason behind the remarkable success of Gram-negative pathogens in developing antibiotic resistance lies in the effectiveness of their outer membrane (OM) in defending the cell from antibacterial compounds. Critical to its function, the highly asymmetric lipid distribution between the inner and outer bilayer leaflets of the OM, adds an extra level of complexity to the study of this crucial defence barrier. Here we review the opportunities offered by neutron scattering techniques, in particular reflectometry, to provide structural information on the interactions of antimicrobials with in vitro models of the OM. The differential sensitivity of neutrons towards hydrogen and deuterium makes them a unique probe to study the structure and behaviour of asymmetric membranes. Molecular-level understanding of the interactions between antimicrobials and the Gram-negative OM provides valuable insights that can aid drug development and broaden our knowledge of this critically important biological barrier.
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31
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Wang Z, Qin Q, Zheng Y, Li F, Zhao Y, Chen GQ. Engineering the permeability of Halomonas bluephagenesis enhanced its chassis properties. Metab Eng 2021; 67:53-66. [PMID: 34098101 DOI: 10.1016/j.ymben.2021.05.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/26/2021] [Accepted: 05/31/2021] [Indexed: 12/24/2022]
Abstract
Bacterial outer membrane (OM), an asymmetric lipid bilayer functioning as a self-protective barrier with reduced permeability for Gram-negative bacteria, yet wasting nutrients and energy to synthesize, has not been studied for its effect on bioproduction. Here we construct several OM-defected halophile Halomonas bluephagenesis strains to investigate the effects of OM on bioproduction. We achieve enhanced chassis properties of H. bluephagenesis based on positive cellular properties among several OM-defected strains. The OM-defected H. bluephagenesis WZY09 demonstrates better adaptation to lower salinity, increasing 28%, 30% and 12% on dry cell mass (DCM), poly(3-hydroxybutyrate) (PHB) accumulation and glucose to PHB conversion rate, respectively, including enlarged cell sizes and 21-folds reduced endotoxin. Interestingly, a poly(3-hydroxybutyrate-co-21mol%4-hydroxybutyrate) (P(3HB-co-21mol%4HB)) is produced by H. bluephagenesis WZY09 derivate WZY249, increasing 60% and 260% on polyhydroxyalkanoate (PHA) production and 4HB content, respectively. Furthermore, increased electroporation efficiency, more sensitive isopropyl β-D-1-thio-galactopyranoside (IPTG) induction, better oxygen uptake, enhanced antibiotics sensitivity and ectoine secretion due to better membrane permeability are observed if OM defected, demonstrating significant OM defection impacts for further metabolic engineering, synthetic biology studies and industrial applications.
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Affiliation(s)
- Ziyu Wang
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Qin Qin
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yifei Zheng
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Fajin Li
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yiqing Zhao
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Guo-Qiang Chen
- School of Life Sciences, Tsinghua University, Beijing, 100084, China; Center for Synthetic and Systems Biology, Tsinghua University, Beijing, 100084, China; Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China; MOE Key Lab of Industrial Biocatalysis, Dept Chemical Engineering, Tsinghua University, Beijing, 100084, China.
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32
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Richter R, Lehr CM. Extracellular vesicles as novel assay tools to study cellular interactions of anti-infective compounds - A perspective. Adv Drug Deliv Rev 2021; 173:492-503. [PMID: 33857554 DOI: 10.1016/j.addr.2021.04.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/21/2021] [Accepted: 04/08/2021] [Indexed: 12/13/2022]
Abstract
Sudden outbreaks of novel infectious diseases and the persistent evolution of antimicrobial resistant pathogens make it necessary to develop specific tools to quickly understand pathogen-cell interactions and to study appropriate drug delivery strategies. Extracellular vesicles (EVs) are cell-specific biogenic transport systems, which are gaining more and more popularity as either diagnostic markers or drug delivery systems. Apart from that, there are emerging possibilities for EVs as tools to study drug penetration, drug-membrane interactions as well as pathogen-membrane interactions. However, it appears that the potential of EVs for such applications has not been fully exploited yet. Considering the vast variety of cells that can be involved in an infection, vesicle-based analytical methods are just emerging and the number of reported applications is still relatively small. Aim of this review is to discuss the current state of the art of EV-based assays, especially in the context of antimicrobial research and therapy, and to present some new perspectives for a more exhaustive and creative exploration in the future.
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Affiliation(s)
- Robert Richter
- Department of Drug Delivery Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS) Helmholtz-Centre for Infection Research (HZI), Campus E8.1, 66123 Saarbrücken, Germany
| | - Claus-Michael Lehr
- Department of Drug Delivery Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS) Helmholtz-Centre for Infection Research (HZI), Campus E8.1, 66123 Saarbrücken, Germany; Department of Pharmacy, Saarland University, Campus E8.1, 66123 Saarbrücken, Germany.
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33
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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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Michalak DJ, Lösche M, Hoogerheide DP. Charge Effects Provide Ångström-Level Control of Lipid Bilayer Morphology on Titanium Dioxide Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:3970-3981. [PMID: 33761262 PMCID: PMC10995910 DOI: 10.1021/acs.langmuir.1c00214] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Interfaces between molecular organic architectures and oxidic substrates are a central feature of biosensors and applications of biomimetics in science and technology. For phospholipid bilayers, the large range of pH- and ionic strength-dependent surface charge densities adopted by titanium dioxide and other oxidic surfaces leads to a rich landscape of phenomena that provides exquisite control of membrane interactions with such substrates. Using neutron reflectometry measurements, we report sharp, reversible transitions that occur between closely surface-associated and weakly coupled states. We show that these states arise from a complex interplay of the tunable length scale of electrostatic interactions with the length scale arising from other forces that are independent of solution conditions. A generalized free energy potential, with its inputs only derived from established measurements of surface and bilayer properties, quantitatively describes these and previously reported observations concerning the unbinding of bilayers from supporting substrates.
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Affiliation(s)
- Dennis J Michalak
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Mathias Lösche
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - David P Hoogerheide
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
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35
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Nielsen JE, Prévost SF, Jenssen H, Lund R. Impact of antimicrobial peptides on E. coli-mimicking lipid model membranes: correlating structural and dynamic effects using scattering methods. Faraday Discuss 2021; 232:203-217. [DOI: 10.1039/d0fd00046a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using X-rays and neutrons we address the effect of AMPs on structure and dynamics of lipids in bacterial model membranes.
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Affiliation(s)
| | | | - Håvard Jenssen
- Department of Science and Environment, Roskilde University, 4000 Roskilde, Denmark
| | - Reidar Lund
- Department of Chemistry, University of Oslo, 0315 Oslo, Norway
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Qian S, Sharma VK, Clifton LA. Understanding the Structure and Dynamics of Complex Biomembrane Interactions by Neutron Scattering Techniques. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:15189-15211. [PMID: 33300335 DOI: 10.1021/acs.langmuir.0c02516] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The membrane is one of the key structural materials of biology at the cellular level. Composed predominantly of a bilayer of lipids with embedded and bound proteins, it defines the boundaries of the cell and many organelles essential to life and therefore is involved in almost all biological processes. Membrane-specific interactions, such as drug binding to a membrane receptor or the interactions of an antimicrobial compound with the lipid matrix of a pathogen membrane, are of interest across the scientific disciplines. Herein we present a review, aimed at nonexperts, of the major neutron scattering techniques used in membrane studies: small-angle neutron scattering, neutron membrane diffraction, neutron reflectometry, quasielastic neutron scattering, and neutron spin echo. Neutron scattering techniques are well suited to studying biological membranes. The nondestructive nature of cold neutrons means that samples can be measured for long periods without fear of beam damage from ultraviolet, electron, or X-ray radiation, and neutron beams are highly penetrating, thus offering flexibility in samples and sample environments. Most important is the strong difference in neutron scattering lengths between the two most abundant forms of hydrogen, protium and deuterium. Changing the relative amounts of protium/deuterium in a sample allows the production of a series of neutron scattering data sets, enabling the observation of differing components within complex membrane architectures. This approach can be as simple as using the naturally occurring neutron contrast between different biomolecules to study components in a complex by changing the solution H2O/D2O ratio or as complex as selectively labeling individual components with hydrogen isotopes. This review presents an overview of each experimental technique with the neutron instrument configuration, related sample preparation and sample environment, and data analysis, highlighted by a special emphasis on using prominent neutron contrast to understand structure and dynamics. This review gives researchers a practical introduction to the often enigmatic suite of neutron beamlines, thereby lowering the barrier to taking advantage of these large-facility techniques to achieve new understandings of membranes and their interactions with other molecules.
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Affiliation(s)
- Shuo Qian
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Veerendra Kumar Sharma
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Luke A Clifton
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire, U.K. OX11 0QX
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Structure, Formation, and Biological Interactions of Supported Lipid Bilayers (SLB) Incorporating Lipopolysaccharide. COATINGS 2020. [DOI: 10.3390/coatings10100981] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Biomimetic membrane systems play a crucial role in the field of biosensor engineering. Over the years, significant progress has been achieved creating artificial membranes by various strategies from vesicle fusion to Langmuir transfer approaches to meet an ever-growing demand for supported lipid bilayers on various substrates such as glass, mica, gold, polymer cushions, and many more. This paper reviews the diversity seen in the preparation of biologically relevant model lipid membranes which includes monolayers and bilayers of phospholipid and other crucial components such as proteins, characterization techniques, changes in the physical properties of the membranes during molecular interactions and the dynamics of the lipid membrane with biologically active molecules with special emphasis on lipopolysaccharides (LPS).
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Lai X, Ding Y, Wu CM, Chen X, Jiang JH, Hsu HY, Wang Y, Le Brun AP, Song J, Han ML, Li J, Shen HH. Phytantriol-Based Cubosome Formulation as an Antimicrobial against Lipopolysaccharide-Deficient Gram-Negative Bacteria. ACS APPLIED MATERIALS & INTERFACES 2020; 12:44485-44498. [PMID: 32942850 DOI: 10.1021/acsami.0c13309] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Treatment of multidrug-resistant (MDR) bacterial infections increasingly relies on last-line antibiotics, such as polymyxins, with the urgent need for discovery of new antimicrobials. Nanotechnology-based antimicrobials have gained significant importance to prevent the catastrophic emergence of MDR over the past decade. In this study, phytantriol-based nanoparticles, named cubosomes, were prepared and examined in vitro by minimum inhibitory concentration (MIC) and time-kill assays against Gram-negative bacteria: Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Phytantriol-based cubosomes were highly bactericidal against polymyxin-resistant, lipopolysaccharide (LPS)-deficient A. baumannii strains. Small-angle neutron scattering (SANS) was employed to understand the structural changes in biomimetic membranes that replicate the composition of these LPS-deficient strains upon treatment with cubosomes. Additionally, to further understand the membrane-cubosome interface, neutron reflectivity (NR) was used to investigate the interaction of cubosomes with model bacterial membranes on a solid support. These results reveal that cubosomes might be a new strategy for combating LPS-deficient Gram-negative pathogens.
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Affiliation(s)
- Xiangfeng Lai
- Department of Materials Science and Engineering, Faculty of Engineering, Monash University, Clayton, Victoria 3800, Australia
| | - Yue Ding
- Department of Materials Science and Engineering, Faculty of Engineering, Monash University, Clayton, Victoria 3800, Australia
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Chun-Ming Wu
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, New South Wales 2232, Australia
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Xiaoyu Chen
- Department of Materials Science and Engineering, Faculty of Engineering, Monash University, Clayton, Victoria 3800, Australia
| | - Jhih-Hang Jiang
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Hsien-Yi Hsu
- School of Energy and Environment & Department of Materials Science and Engineering, City University of Hong Kong, Kowloon Tong, Hong Kong, China
- Shenzhen Research Institute of City University of Hong Kong, Shenzhen 518057, China
| | - Yajun Wang
- College of Chemistry & Materials Engineering, Wenzhou University, Wenzhou 325027, Zhejiang, China
| | - Anton P Le Brun
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, New South Wales 2232, Australia
| | - Jiangning Song
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Mei-Ling Han
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Jian Li
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Hsin-Hui Shen
- Department of Materials Science and Engineering, Faculty of Engineering, Monash University, Clayton, Victoria 3800, Australia
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
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Sharma P, Parthasarathi S, Patil N, Waskar M, Raut JS, Puranik M, Ayappa KG, Basu JK. Assessing Barriers for Antimicrobial Penetration in Complex Asymmetric Bacterial Membranes: A Case Study with Thymol. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:8800-8814. [PMID: 32609530 DOI: 10.1021/acs.langmuir.0c01124] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The bacterial cell envelope is a complex multilayered structure evolved to protect bacteria in hostile environments. An understanding of the molecular basis for the interaction and transport of antibacterial therapeutics with the bacterial cell envelope will enable the development of drug molecules to combat bacterial infections and suppress the emergence of drug-resistant strains. Here we report the successful creation of an in vitro supported lipid bilayer (SLB) platform of the outer membrane (OM) of E. coli, an archetypical Gram-negative bacterium, containing the full smooth lipopolysaccharide (S-LPS) architecture of the membrane. Using this platform, we performed fluorescence correlation spectroscopy (FCS) in combination with molecular dynamics (MD) simulations to measure lipid diffusivities and provide molecular insights into the transport of natural antimicrobial agent thymol. Lipid diffusivities measured on symmetric supported lipid bilayers made up of inner membrane lipids show a distinct increase in the presence of thymol as also corroborated by MD simulations. However, lipid diffusivities in the asymmetric OM consisting of only S-LPS are invariant upon exposure to thymol. Increasing the phospholipid content in the LPS-containing outer leaflet improved the penetration toward thymol as reflected in slightly higher relative diffusivity changes in the inner leaflet when compared with the outer leaflet. Free-energy computations reveal the presence of a barrier (∼6 kT) only in the core-saccharide region of the OM for the translocation of thymol while the external O-antigen part is easily traversed. In contrast, thymol spontaneously inserts into the inner membrane. In addition to providing leaflet-resolved penetration barriers in bacterial membranes, we also assess the ability of small molecules to penetrate various membrane components. With rising bacterial resistance, our study opens up the possibility of screening potential antimicrobial drug candidates using these realistic model platforms for Gram-negative bacteria.
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Affiliation(s)
| | | | - Nivedita Patil
- Unilever RD Bangalore, 64 Main Road, Whitefield, Bangalore 560066, India
| | - Morris Waskar
- Unilever RD Bangalore, 64 Main Road, Whitefield, Bangalore 560066, India
| | - Janhavi S Raut
- Unilever RD Bangalore, 64 Main Road, Whitefield, Bangalore 560066, India
| | - Mrinalini Puranik
- Unilever RD Bangalore, 64 Main Road, Whitefield, Bangalore 560066, India
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Abstract
Over the last 10 years, neutron reflectometry (NR) has emerged as a powerful technique for the investigation of biologically relevant thin films. The great advantage of NR with respect to many other surface-sensitive techniques is its sub-nanometer resolution that enables structural characterizations at the molecular level. In the case of bio-relevant samples, NR is non-destructive and can be used to probe thin films at buried interfaces or enclosed in bulky sample environment equipment. Moreover, recent advances in biomolecular deutera-tion enabled new labeling strategies to highlight certain structural features and to resolve with better accuracy the location of chemically similar molecules within a thin film.
In this chapter I will describe some applications of NR to bio-relevant samples and discuss some of the data analysis approaches available for biological thin films. In particular, examples on the structural characterization of biomembranes, protein films and protein-lipid interactions will be described.
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Vandera KKA, Picconi P, Valero M, González-Gaitano G, Woods A, Zain NMM, Bruce KD, Clifton LA, Skoda MWA, Rahman KM, Harvey RD, Dreiss CA. Antibiotic-in-Cyclodextrin-in-Liposomes: Formulation Development and Interactions with Model Bacterial Membranes. Mol Pharm 2020; 17:2354-2369. [DOI: 10.1021/acs.molpharmaceut.0c00096] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Kalliopi-Kelli A. Vandera
- School of Cancer & Pharmaceutical Science, Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
| | - Pietro Picconi
- School of Cancer & Pharmaceutical Science, Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
| | - Margarita Valero
- Department of Physical Chemistry, University of Salamanca, ES E-37007 Salamanca, Spain
| | | | - Arcadia Woods
- School of Cancer & Pharmaceutical Science, Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
| | - Nur Masirah M. Zain
- School of Cancer & Pharmaceutical Science, Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
| | - Kenneth D. Bruce
- School of Cancer & Pharmaceutical Science, Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
| | - Luke A. Clifton
- Rutherford Appleton Laboratory, ISIS, 1-27, R3, Harwell Campus, Didcot OX11 0QX, U.K
| | | | - Khondaker Miraz Rahman
- School of Cancer & Pharmaceutical Science, Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
| | - Richard D. Harvey
- Department of Pharmaceutical Chemistry, University of Vienna, Althanstraße 14, Vienna, Austria
| | - Cécile A. Dreiss
- School of Cancer & Pharmaceutical Science, Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
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Abstract
Gram-negative bacteria are protected by a multicompartmental molecular architecture known as the cell envelope that contains two membranes and a thin cell wall. As the cell envelope controls influx and efflux of molecular species, in recent years both experimental and computational studies of such architectures have seen a resurgence due to the implications for antibiotic development. In this article we review recent progress in molecular simulations of bacterial membranes. We show that enormous progress has been made in terms of the lipidic and protein compositions of bacterial systems. The simulations have moved away from the traditional setup of one protein surrounded by a large patch of the same lipid type toward a more bio-logically representative viewpoint. Simulations with multiple cell envelope components are also emerging. We review some of the key method developments that have facilitated recent progress, discuss some current limitations, and offer a perspective on future directions.
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Affiliation(s)
- Wonpil Im
- Departments of Biological Sciences and Bioengineering, Lehigh University, Bethlehem, Pennsylvania 18015, USA
- School of Computational Sciences, Korea Institute for Advanced Study, Seoul 02455, Republic of Korea
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton S017 1BJ, United Kingdom
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Schimek C, Egger E, Tauer C, Striedner G, Brocard C, Cserjan-Puschmann M, Hahn R. Extraction of recombinant periplasmic proteins under industrially relevant process conditions: Selectivity and yield strongly depend on protein titer and methodology. Biotechnol Prog 2020; 36:e2999. [PMID: 32259401 PMCID: PMC7685146 DOI: 10.1002/btpr.2999] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 03/25/2020] [Accepted: 04/01/2020] [Indexed: 02/05/2023]
Abstract
In this work, we attempted to identify a method for the selective extraction of periplasmic endogenously expressed proteins, which is applicable at an industrial scale. For this purpose, we used an expression model that allows coexpression of two fluorescent proteins, each of which is specifically targeted to either the cytoplasm or periplasm. We assessed a number of scalable lysis methods (high‐pressure homogenization, osmotic shock procedures, extraction with ethylenediaminetetraacetic acid, and extraction with deoxycholate) for the ability to selectively extract periplasmic proteins rather than cytoplasmic proteins. Our main conclusion was that although we identified industrially scalable lysis conditions that significantly increased the starting purity for further purification, none of the tested conditions were selective for periplasmic protein over cytoplasmic protein. Furthermore, we demonstrated that efficient extraction of the expressed recombinant proteins was largely dependent on the overall protein concentration in the cell.
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Affiliation(s)
- Clemens Schimek
- Christian Doppler Laboratory for Production of Next-Level Biopharmaceuticals in E. coli, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Esther Egger
- Christian Doppler Laboratory for Production of Next-Level Biopharmaceuticals in E. coli, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Christopher Tauer
- Christian Doppler Laboratory for Production of Next-Level Biopharmaceuticals in E. coli, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Gerald Striedner
- Christian Doppler Laboratory for Production of Next-Level Biopharmaceuticals in E. coli, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Cécile Brocard
- Biopharma Process Science, Boehringer Ingelheim RCV GmbH & Co KG, Wien, Austria
| | - Monika Cserjan-Puschmann
- Christian Doppler Laboratory for Production of Next-Level Biopharmaceuticals in E. coli, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Rainer Hahn
- Christian Doppler Laboratory for Production of Next-Level Biopharmaceuticals in E. coli, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
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Clifton LA, Paracini N, Hughes AV, Lakey JH, Steinke NJ, Cooper JFK, Gavutis M, Skoda MWA. Self-Assembled Fluid Phase Floating Membranes with Tunable Water Interlayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:13735-13744. [PMID: 31553881 DOI: 10.1021/acs.langmuir.9b02350] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We present a reliable method for the fabrication of fluid phase, unsaturated lipid bilayers by self-assembly onto charged Self-Assembled Monolayer (SAM) surfaces with tunable membrane to surface aqueous interlayers. Initially, the formation of water interlayers between membranes and charged surfaces was characterized using a comparative series of bilayers deposited onto charged, self-assembled monolayers by sequential layer deposition. Using neutron reflectometry, a bilayer to surface water interlayer of ∼8 Å was found between the zwitterionic phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) membrane and an anionic carboxyl terminated grafted SAM with the formation of this layer attributed to bilayer repulsion by hydration water on the SAM surface. Furthermore, we found we could significantly reduce the technical complexity of sample fabrication through self-assembly of planar membranes onto the SAM coated surfaces. Vesicle fusion onto carboxyl-terminated monolayers yielded high coverage (>95%) bilayers of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) which floated on a 7-11 Å solution interlayer between the membrane and the surface. The surface to membrane distance was then tuned via the addition of 200 mM NaCl to the bulk solution immersing a POPC floating membrane, which caused the water interlayer to swell reversibly to ∼33 Å. This study reveals that biomimetic membrane models can be readily self-assembled from solution onto functionalized surfaces without the use of polymer supports or tethers. Once assembled, surface to membrane distance can be tailored to the experimental requirements using physiological concentrations of electrolytes. These planar bilayers only very weakly interact with the substrate and are ideally suited for use as biomimetic models for accurate in vitro biochemical and biophysical studies, as well as for technological applications, such as biosensors.
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Affiliation(s)
- Luke A Clifton
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council , Rutherford Appleton Laboratory, Harwell Science and Innovation Campus , Didcot , Oxfordshire OX11 OQX , U.K
| | - Nicoló Paracini
- Institute for Cell and Molecular Biosciences , Newcastle University , Framlington Place , Newcastle upon Tyne , NE2 4HH , United Kingdom
| | - Arwel V Hughes
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council , Rutherford Appleton Laboratory, Harwell Science and Innovation Campus , Didcot , Oxfordshire OX11 OQX , U.K
| | - Jeremy H Lakey
- Institute for Cell and Molecular Biosciences , Newcastle University , Framlington Place , Newcastle upon Tyne , NE2 4HH , United Kingdom
| | - Nina-Juliane Steinke
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council , Rutherford Appleton Laboratory, Harwell Science and Innovation Campus , Didcot , Oxfordshire OX11 OQX , U.K
| | - Joshaniel F K Cooper
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council , Rutherford Appleton Laboratory, Harwell Science and Innovation Campus , Didcot , Oxfordshire OX11 OQX , U.K
| | - Martynas Gavutis
- Department of Nanoengineering , Center for Physical Sciences and Technology , Savanoriu ave 231 , LT-02300 Vilnius , Lithuania
| | - Maximilian W A Skoda
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council , Rutherford Appleton Laboratory, Harwell Science and Innovation Campus , Didcot , Oxfordshire OX11 OQX , U.K
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Jindal S, Yang L, Day PJ, Kell DB. Involvement of multiple influx and efflux transporters in the accumulation of cationic fluorescent dyes by Escherichia coli. BMC Microbiol 2019; 19:195. [PMID: 31438868 PMCID: PMC6704527 DOI: 10.1186/s12866-019-1561-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 07/31/2019] [Indexed: 12/11/2022] Open
Abstract
Background It is widely believed that most xenobiotics cross biomembranes by diffusing through the phospholipid bilayer, and that the use of protein transporters is an occasional adjunct. According to an alternative view, phospholipid bilayer transport is negligible, and several different transporters may be involved in the uptake of an individual molecular type. We recognise here that the availability of gene knockout collections allows one to assess the contributions of all potential transporters, and flow cytometry based on fluorescence provides a convenient high-throughput assay for xenobiotic uptake in individual cells. Results We used high-throughput flow cytometry to assess the ability of individual gene knockout strains of E coli to take up two membrane-permeable, cationic fluorescent dyes, namely the carbocyanine diS-C3(5) and the DNA dye SYBR Green. Individual strains showed a large range of distributions of uptake. The range of modal steady-state uptakes for the carbocyanine between the different strains was 36-fold. Knockouts of the ATP synthase α- and β-subunits greatly inhibited uptake, implying that most uptake was ATP-driven rather than being driven by a membrane potential. Dozens of transporters changed the steady-state uptake of the dye by more than 50% with respect to that of the wild type, in either direction (increased or decreased); knockouts of known influx and efflux transporters behaved as expected, giving credence to the general strategy. Many of the knockouts with the most reduced uptake were transporter genes of unknown function (‘y-genes’). Similarly, several overexpression variants in the ‘ASKA’ collection had the anticipated, opposite effects. Similar results were obtained with SYBR Green (the range being approximately 69-fold). Although it too contains a benzothiazole motif there was negligible correlation between its uptake and that of the carbocyanine when compared across the various strains (although the membrane potential is presumably the same in each case). Conclusions Overall, we conclude that the uptake of these dyes may be catalysed by a great many transporters of putatively broad and presently unknown specificity, and that the very large range between the ‘lowest’ and the ‘highest’ levels of uptake, even in knockouts of just single genes, implies strongly that phospholipid bilayer transport is indeed negligible. This work also casts serious doubt upon the use of such dyes as quantitative stains for representing either bioenergetic parameters or the amount of cellular DNA in unfixed cells (in vivo). By contrast, it opens up their potential use as transporter assay substrates in high-throughput screening. Electronic supplementary material The online version of this article (10.1186/s12866-019-1561-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Srijan Jindal
- Department of Chemistry, The University of Manchester, 131 Princess St, Manchester, M1 7DN, UK.,Manchester Institute of Biotechnology, The University of Manchester, 131 Princess St, Manchester, M1 7DN, UK.,Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK
| | - Lei Yang
- Novo Nordisk Foundation Centre for Biosustainability, Technical University of Denmark, Building 220, Kemitorvet, 2800 Kgs, Lyngby, Denmark
| | - Philip J Day
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess St, Manchester, M1 7DN, UK.,Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK
| | - Douglas B Kell
- Department of Chemistry, The University of Manchester, 131 Princess St, Manchester, M1 7DN, UK. .,Manchester Institute of Biotechnology, The University of Manchester, 131 Princess St, Manchester, M1 7DN, UK. .,Novo Nordisk Foundation Centre for Biosustainability, Technical University of Denmark, Building 220, Kemitorvet, 2800 Kgs, Lyngby, Denmark. .,Department of Biochemistry, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Crown St, Liverpool, L69 7ZB, UK.
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46
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Skoda MW. Recent developments in the application of X-ray and neutron reflectivity to soft-matter systems. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.03.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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47
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Lakey JH. Recent advances in neutron reflectivity studies of biological membranes. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.02.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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48
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Lind TK, Skoda MWA, Cárdenas M. Formation and Characterization of Supported Lipid Bilayers Composed of Phosphatidylethanolamine and Phosphatidylglycerol by Vesicle Fusion, a Simple but Relevant Model for Bacterial Membranes. ACS OMEGA 2019; 4:10687-10694. [PMID: 31460166 PMCID: PMC6648305 DOI: 10.1021/acsomega.9b01075] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 06/06/2019] [Indexed: 05/06/2023]
Abstract
Supported lipid bilayers (SLBs) are simple and robust biomimics with controlled lipid composition that are widely used as models of both mammalian and bacterial membranes. However, the lipids typically used for SLB formation poorly resemble those of bacterial cell membranes due to the lack of available protocols to form SLBs using mixtures of lipids relevant for bacteria such as phosphatidylethanolamine (PE) and phosphatidylglycerol (PG). Although a few reports have been published recently on the formation of SLBs from Escherichia coli lipid extracts, a detailed understanding of these systems is challenging due to the complexity of the lipid composition in such natural extracts. Here, we present for the first time a simple and reliable protocol optimized to form high-quality SLBs using mixtures of PE and PG at compositions relevant for Gram-negative membranes. We show using neutron reflection and quartz microbalance not only that Ca2+ ions and temperature are key parameters for successful bilayer deposition but also that mass transfer to the surface is a limiting factor. Continuous flow of the lipid suspension is thus crucial for obtaining full SLB coverage. We furthermore characterize the resulting bilayers and report structural parameters, for the first time for PE and PG mixtures, which are in good agreement with those reported earlier for pure POPE vesicles. With this protocol in place, more suitable and reproducible studies can be conducted to understand biomolecular processes occurring at cell membranes, for example, for testing specificities and to unravel the mechanism of interaction of antimicrobial peptides.
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Affiliation(s)
- Tania Kjellerup Lind
- Biofilms Research
Centre for Biointerfaces and Biomedical Science Department, Faculty
of Health and Society, Malmo University, Malmo 20506, Sweden
| | | | - Marité Cárdenas
- Biofilms Research
Centre for Biointerfaces and Biomedical Science Department, Faculty
of Health and Society, Malmo University, Malmo 20506, Sweden
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Hughes GW, Hall SCL, Laxton CS, Sridhar P, Mahadi AH, Hatton C, Piggot TJ, Wotherspoon PJ, Leney AC, Ward DG, Jamshad M, Spana V, Cadby IT, Harding C, Isom GL, Bryant JA, Parr RJ, Yakub Y, Jeeves M, Huber D, Henderson IR, Clifton LA, Lovering AL, Knowles TJ. Evidence for phospholipid export from the bacterial inner membrane by the Mla ABC transport system. Nat Microbiol 2019; 4:1692-1705. [DOI: 10.1038/s41564-019-0481-y] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 05/03/2019] [Indexed: 12/24/2022]
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50
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Jefferies D, Shearer J, Khalid S. Role of O-Antigen in Response to Mechanical Stress of the E. coli Outer Membrane: Insights from Coarse-Grained MD Simulations. J Phys Chem B 2019; 123:3567-3575. [DOI: 10.1021/acs.jpcb.8b12168] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Damien Jefferies
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
| | - Jonathan Shearer
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
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