1
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Lee TH, Charchar P, Separovic F, Reid GE, Yarovsky I, Aguilar MI. The intricate link between membrane lipid structure and composition and membrane structural properties in bacterial membranes. Chem Sci 2024; 15:3408-3427. [PMID: 38455013 PMCID: PMC10915831 DOI: 10.1039/d3sc04523d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Accepted: 01/26/2024] [Indexed: 03/09/2024] Open
Abstract
It is now evident that the cell manipulates lipid composition to regulate different processes such as membrane protein insertion, assembly and function. Moreover, changes in membrane structure and properties, lipid homeostasis during growth and differentiation with associated changes in cell size and shape, and responses to external stress have been related to drug resistance across mammalian species and a range of microorganisms. While it is well known that the biomembrane is a fluid self-assembled nanostructure, the link between the lipid components and the structural properties of the lipid bilayer are not well understood. This perspective aims to address this topic with a view to a more detailed understanding of the factors that regulate bilayer structure and flexibility. We describe a selection of recent studies that address the dynamic nature of bacterial lipid diversity and membrane properties in response to stress conditions. This emerging area has important implications for a broad range of cellular processes and may open new avenues of drug design for selective cell targeting.
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Affiliation(s)
- Tzong-Hsien Lee
- Department of Biochemistry and Molecular Biology, Monash University Clayton VIC 3800 Australia
| | - Patrick Charchar
- School of Engineering, RMIT University Melbourne Victoria 3001 Australia
| | - Frances Separovic
- School of Chemistry, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne VIC 3010 Australia
| | - Gavin E Reid
- School of Chemistry, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne VIC 3010 Australia
- Department of Biochemistry and Pharmacology, University of Melbourne Parkville VIC 3010 Australia
| | - Irene Yarovsky
- School of Engineering, RMIT University Melbourne Victoria 3001 Australia
| | - Marie-Isabel Aguilar
- Department of Biochemistry and Molecular Biology, Monash University Clayton VIC 3800 Australia
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2
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Adhyapak P, Liang K, Duan M, Kapoor S. Effect of Host Cholesterol on the Membrane Dynamics of Outer Membrane Lipids of Mycobacteria. Chem Asian J 2023; 18:e202300697. [PMID: 37846643 DOI: 10.1002/asia.202300697] [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: 08/09/2023] [Revised: 10/16/2023] [Accepted: 10/17/2023] [Indexed: 10/18/2023]
Abstract
The ability of Mycobacterium tuberculosis to remain dormant after primary infection represents the prime cause of new TB cases throughout the world. Hence, diagnosis and treatment of individuals hosting dormant mycobacterium is one of the crucial strategies to be adopted for the prevention of Tuberculosis. Among many strategies unleashed by the latent bacterium, one of them is scavenging host cholesterol for carbon source. Cholesterol modifies lipid membranes over many scales and here, its effect on mycobacterial membrane biophysics and the subsequent effect on partitioning of antibiotics into cholesterol- enriched mycobacterial membranes was investigated. Our research showed that cholesterol alters the phase state behavior of mycobacterial outer membrane lipids by enhancing the overall membrane order at the headgroup and acyl chain region and is integrated into both ordered and disordered domains/phases, with a preference for the latter. Exogenous cholesterol further alters the drug partitioning behavior of structurally different drugs, pointing to a larger clinical potential of using more hydrophobic medications to target dormant bacteria.
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Affiliation(s)
- Pranav Adhyapak
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, 400076, India
| | - Kuan Liang
- National Centre for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430071, Hubei, China
| | - Mojie Duan
- National Centre for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430071, Hubei, China
| | - Shobhna Kapoor
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, 400076, India
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3
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Goodchild J, Walsh DL, Laurent H, Connell SD. PDMS as a Substrate for Lipid Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:10843-10854. [PMID: 37494418 PMCID: PMC10413950 DOI: 10.1021/acs.langmuir.3c00944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Revised: 06/13/2023] [Indexed: 07/28/2023]
Abstract
PDMS (polydimethylsiloxane) is a cheap, optically clear polymer that is elastic and can be easily and quickly fabricated into a wide array of microscale and nanoscale architectures, making it a versatile substrate for biophysical experiments on cell membranes. It is easy to imagine many new experiments will be devised that require a bilayer to be placed upon a substrate that is flexible or easily cast into a desired geometry, such as in lab-on-a-chip, organ-on-chip, and microfluidic applications, or for building accurate membrane models that replicate the surface structure and elasticity of the cytoskeleton. However, PDMS has its limitations, and the extent to which the behavior of membranes is affected on PDMS has not been fully explored. We use AFM and fluorescence optical microscopy to investigate the use of PDMS as a substrate for the formation and study of supported lipid bilayers (SLBs). Lipid bilayers form on plasma-treated PDMS and show free diffusion and normal phase transitions, confirming its suitability as a model bilayer substrate. However, lipid-phase separation on PDMS is severely restricted due to the pinning of domains to surface roughness, resulting in the cessation of lateral hydrodynamic flow. We show the high-resolution porous structure of PDMS and the extreme smoothing effect of oxygen plasma treatment used to hydrophilize the surface, but this is not flat enough to allow domain formation. We also observe bilayer degradation over hour timescales, which correlates with the known hydrophobic recovery of PDMS, and establish a critical water contact angle of 30°, above which bilayers degrade or not form at all. Care must be taken as incomplete surface oxidation and hydrophobic recovery result in optically invisible membrane disruption, which will also be transparent to fluorescence microscopy and lipid diffusion measurements in the early stages.
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Affiliation(s)
- James
A. Goodchild
- Molecular
and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Danielle L. Walsh
- Molecular
and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Harrison Laurent
- Molecular
and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Simon D. Connell
- Molecular
and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
- Bragg
Centre for Materials Research, William Henry Bragg Building, University of Leeds, Leeds LS2 9JT, United Kingdom
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4
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Polita A, Stancikaitė M, Žvirblis R, Maleckaitė K, Dodonova-Vaitkūnienė J, Tumkevičius S, Shivabalan AP, Valinčius G. Designing a green-emitting viscosity-sensitive 4,4-difluoro-4-bora-3a,4a-diaza- s-indacene (BODIPY) probe for plasma membrane viscosity imaging. RSC Adv 2023; 13:19257-19264. [PMID: 37377877 PMCID: PMC10291278 DOI: 10.1039/d3ra04126c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 06/20/2023] [Indexed: 06/29/2023] Open
Abstract
Viscosity is a key characteristic of lipid membranes - it governs the passive diffusion of solutes and affects the lipid raft formation and membrane fluidity. Precise determination of viscosity values in biological systems is of great interest and viscosity-sensitive fluorescent probes offer a convenient solution for this task. In this work we present a novel membrane-targeting and water-soluble viscosity probe BODIPY-PM, which is based on one of the most frequently used probes BODIPY-C10. Despite its regular use, BODIPY-C10 suffers from poor integration into liquid-ordered lipid phases and lack of water solubility. Here, we investigate the photophysical characteristics of BODIPY-PM and demonstrate that solvent polarity only slightly affects the viscosity-sensing qualities of BODIPY-PM. In addition, with fluorescence lifetime imaging microscopy (FLIM), we imaged microviscosity in complex biological systems - large unilamellar vesicles (LUVs), tethered bilayer membranes (tBLMs) and live lung cancer cells. Our study showcases that BODIPY-PM preferentially stains the plasma membranes of live cells, equally well partitions into both liquid-ordered and liquid-disordered phases and reliably distinguishes lipid phase separation in tBLMs and LUVs.
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Affiliation(s)
- Artūras Polita
- Institute of Biochemistry, Life Sciences Center, Vilnius University Saulėtekio Av. 7 Vilnius LT-10257 Lithuania
| | - Milda Stancikaitė
- Center of Physical Sciences and Technology Saulėtekio Av. 3 Vilnius LT-10257 Lithuania
| | - Rokas Žvirblis
- Life Sciences Center, Institute of Biotechnology, Vilnius University Saulėtekio Av. 7 Vilnius LT-10257 Lithuania
| | - Karolina Maleckaitė
- Center of Physical Sciences and Technology Saulėtekio Av. 3 Vilnius LT-10257 Lithuania
| | - Jelena Dodonova-Vaitkūnienė
- Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University Naugarduko St. 24 Vilnius LT-03225 Lithuania
| | - Sigitas Tumkevičius
- Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University Naugarduko St. 24 Vilnius LT-03225 Lithuania
| | - Arun Prabha Shivabalan
- Institute of Biochemistry, Life Sciences Center, Vilnius University Saulėtekio Av. 7 Vilnius LT-10257 Lithuania
| | - Gintaras Valinčius
- Institute of Biochemistry, Life Sciences Center, Vilnius University Saulėtekio Av. 7 Vilnius LT-10257 Lithuania
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5
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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: 5] [Impact Index Per Article: 5.0] [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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6
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Anosov A, Astanina P, Proskuryakov I, Koplak O, Morgunov R. Surface and Structure of Phosphatidylcholine Membranes Reconstructed with CoFe 2O 4 Nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:14517-14526. [PMID: 36383134 DOI: 10.1021/acs.langmuir.2c02659] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Structural changes in phosphatidylcholine lipid membranes caused by the introduction of insoluble CoFe2O4 nanoparticles (NPs) are analyzed. Changes in nuclear magnetic resonance spectrum, infrared spectrum, and ionic conductivity of membranes are observed with the addition of NPs. The presence of NPs in membranes is proved by atomic force and magnetic force microscopy. Structural changes in the membranes in the vicinity of the lipid C-O bonds caused by NPs are observed by Scanning near-field optical microscopy. Analysis of nuclear magnetic resonance (NMR) spectra allowed us to identify the affected atomic groups in the membrane surface layers. Conductivity measurements of the bilayer membranes were performed in DC as well as in time-resolved modes. Hydrophobic NPs stimulate surface distortion and creation of pores, which depending on NP concentration leads to an increase in the ionic conductivity of membranes. Concentration dependence demonstrating percolation threshold was analyzed in the frame of the fractal theory approach.
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Affiliation(s)
- Andrey Anosov
- I.M. Sechenov First Moscow State Medical University, 119435 Moscow, Russia
- Kotelnikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 125009 Moscow, Russia
| | - Polina Astanina
- Federal Research Center of Problem of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Chernogolovka, 142432 Moscow, Russia
| | - Ivan Proskuryakov
- Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, 142290 Moscow, Russia
| | - Oksana Koplak
- I.M. Sechenov First Moscow State Medical University, 119435 Moscow, Russia
- Federal Research Center of Problem of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Chernogolovka, 142432 Moscow, Russia
| | - Roman Morgunov
- I.M. Sechenov First Moscow State Medical University, 119435 Moscow, Russia
- Federal Research Center of Problem of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Chernogolovka, 142432 Moscow, Russia
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7
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Panahi M, Rad VF, Sasan S, Jamali R, Moradi AR, Darudi A. Detection of intralayer alignment in multicomponent lipids by dynamic speckle pattern analysis. JOURNAL OF BIOPHOTONICS 2022; 15:e202200034. [PMID: 35460181 DOI: 10.1002/jbio.202200034] [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: 02/09/2022] [Revised: 04/08/2022] [Accepted: 04/19/2022] [Indexed: 06/14/2023]
Abstract
Multicomponent mixtures of bilayer lipids, thanks to the coexistence of liquid-crystalline phases in their structures, may be used in the development of functional membranes. In such membranes interlayer ordering distributes across membrane lamellae, resulting in long-range alignment of phase-separated domains. In this paper, we explore the dynamics of this phenomenon by laser speckle pattern analysis. We show that cholesterol content decreases the activity, and the rate of the domains size development is related to the change of physical roughness of the multicomponent lipid mixture. Our results are in agreement with the previous experimental reports. However, our experimental procedure is an easy-to-implement and effective methodology.
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Affiliation(s)
- Majid Panahi
- Department of Physics, Faculty of Science, University of Zanjan, Zanjan, Iran
- Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran
| | - Vahideh Farzam Rad
- Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran
| | - Shiva Sasan
- Department of Physics, Faculty of Science, University of Zanjan, Zanjan, Iran
| | - Ramin Jamali
- Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran
| | - Ali-Reza Moradi
- Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran
- School of Nano Science, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran
| | - Ahmad Darudi
- Department of Physics, Faculty of Science, University of Zanjan, Zanjan, Iran
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8
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Moraille P, Abdali Z, Ramkaran M, Polcari D, Patience GS, Dorval Courchesne N, Badia A. Experimental Methods in Chemical Engineering: Atomic force microscopy—
AFM. CAN J CHEM ENG 2022. [DOI: 10.1002/cjce.24407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
| | - Zahra Abdali
- Chemical Engineering, McGill University Québec Canada
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9
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Shrestha R, Chen D, Frank P, Nissley DV, Turbyville TJ. Recapitulation of cell-like KRAS4b membrane dynamics on complex biomimetic membranes. iScience 2022; 25:103608. [PMID: 35106460 PMCID: PMC8786645 DOI: 10.1016/j.isci.2021.103608] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 09/30/2021] [Accepted: 12/08/2021] [Indexed: 12/22/2022] Open
Abstract
Understanding the spatiotemporal distribution and dynamics of RAS on the plasma membrane (PM) is the key for elucidating the molecular mechanisms of the RAS signaling pathway. Single particle tracking (SPT) experiments show that in cells, KRAS diffuses in at least three interchanging states on the cellular PM; however, KRAS remains monomeric and always shows homogeneous diffusion on artificial membranes. Here, we show for the first time on a supported lipid bilayer composed of heterogeneous lipid components that we can recapitulate the three-state diffusion of KRAS seen in cells. The use of a biologically relevant eight-lipid system opens a new frontier in the biophysical studies of RAS and other membrane associated proteins on a biomimetic system that recapitulates the complexity of a cellular PM. KRAS4b shows homogeneous diffusion on simple 2-lipids bilayer KRAS4b shows a cell-like, three-state diffusion on a complex 8-lipid bilayer Phase separation in lipids favors the multi-state diffusion of KRAS4b The complex lipid composition favors RAS nanoclustering irrespective of nucleotide state
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Affiliation(s)
- Rebika Shrestha
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702, USA
| | - De Chen
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702, USA
| | - Peter Frank
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702, USA
| | - Dwight V Nissley
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702, USA
| | - Thomas J Turbyville
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702, USA
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10
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Ausilio C, Lubrano C, Mariano A, Santoro F. Negatively-charged supported lipid bilayers regulate neuronal adhesion and outgrowth. RSC Adv 2022; 12:30270-30277. [PMCID: PMC9590245 DOI: 10.1039/d2ra05147h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 10/14/2022] [Indexed: 11/07/2022] Open
Abstract
Primary cortical neurons were cultured on negatively charged supported lipid bilayers (SLBs). Such membranes demonstrated the potential effect of negative charges on neuronal growth and neurite branching and elongation.
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Affiliation(s)
- Chiara Ausilio
- Tissue Electronics, Istituto Italiano di Tecnologia, 80125 Napoli, Italy
| | - Claudia Lubrano
- Tissue Electronics, Istituto Italiano di Tecnologia, 80125 Napoli, Italy
- Dipartimento di Chimica, Materiali e Produzione Industriale, Università di Napoli Federico II, 80125, Naples, Italy
- Faculty of Electrical Engineering and Information Technology, RWTH Aachen, 52074, Germany
- Institute for Biological Information Processing-Bioelectronics, IBI-3, Forschungszentrum Juelich, 52428, Germany
| | - Anna Mariano
- Tissue Electronics, Istituto Italiano di Tecnologia, 80125 Napoli, Italy
| | - Francesca Santoro
- Tissue Electronics, Istituto Italiano di Tecnologia, 80125 Napoli, Italy
- Faculty of Electrical Engineering and Information Technology, RWTH Aachen, 52074, Germany
- Institute for Biological Information Processing-Bioelectronics, IBI-3, Forschungszentrum Juelich, 52428, Germany
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11
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Toyofuku M, Kikuchi Y, Taoka A. A Single Shot of Vesicles. Microbes Environ 2022; 37. [PMID: 36504177 PMCID: PMC10037094 DOI: 10.1264/jsme2.me22083] [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] [Indexed: 12/13/2022] Open
Abstract
Bacteria communicate through signaling molecules that coordinate group behavior. Hydrophobic signals that do not diffuse in aqueous environments are used as signaling molecules by several bacteria. However, limited information is currently available on the mechanisms by which these molecules are transported between cells. Membrane vesicles (MVs) with diverse functions play important roles in the release and delivery of hydrophobic signaling molecules, leading to differences in the dynamics of signal transportation from those of free diffusion. Studies on Paracoccus denitrificans, which produces a hydrophobic long-chain N-acyl homoserine lactone (AHL), showed that signals were loaded into MVs at a concentration with the potential to trigger the quorum sensing (QS) response with a "single shot" to the cell. Furthermore, stimulating the formation of MVs increased the release of signals from the cell; therefore, a basic understanding of MV formation is important. Novel findings revealed the formation of MVs through different routes, resulting in the production of different types of MVs. Methods such as high-speed atomic force microscopy (AFM) phase imaging allow the physical properties of MVs to be analyzed at a nanometer resolution, revealing their heterogeneity. In this special minireview, we introduce the role of MVs in bacterial communication and highlight recent findings on MV formation and their physical heterogeneity by referring to our research. We hope that this minireview will provide basic information for understanding the functionality of MVs in ecological systems.
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Affiliation(s)
- Masanori Toyofuku
- Faculty of Life and Environmental Sciences, University of Tsukuba
- Microbiology Research Center for Sustainability (MiCS), University of Tsukuba
| | - Yousuke Kikuchi
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University
| | - Azuma Taoka
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University
- Institute of Science and Engineering, Kanazawa University
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12
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Hodel AW, Rudd-Schmidt JA, Trapani JA, Voskoboinik I, Hoogenboom BW. Lipid specificity of the immune effector perforin. Faraday Discuss 2021; 232:236-255. [PMID: 34545865 PMCID: PMC8704153 DOI: 10.1039/d0fd00043d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 08/13/2020] [Indexed: 12/16/2022]
Abstract
Perforin is a pore forming protein used by cytotoxic T lymphocytes to remove cancerous or virus-infected cells during the immune response. During the response, the lymphocyte membrane becomes refractory to perforin function by accumulating densely ordered lipid rafts and externalizing negatively charged lipid species. The dense membrane packing lowers the capacity of perforin to bind, and the negatively charged lipids scavenge any residual protein before pore formation. Using atomic force microscopy on model membrane systems, we here provide insight into the molecular basis of perforin lipid specificity.
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Affiliation(s)
- Adrian W Hodel
- Killer Cell Biology Laboratory, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne, VIC 3000, Australia.
- London Centre for Nanotechnology, University College London, 19 Gordon Street, London WC1H 0AH, UK.
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Jesse A Rudd-Schmidt
- Killer Cell Biology Laboratory, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne, VIC 3000, Australia.
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, VIC 3000, Australia
| | - Joseph A Trapani
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, VIC 3000, Australia
- Cancer Cell Death Laboratory, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne, VIC 3000, Australia
| | - Ilia Voskoboinik
- Killer Cell Biology Laboratory, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne, VIC 3000, Australia.
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, VIC 3000, Australia
| | - Bart W Hoogenboom
- London Centre for Nanotechnology, University College London, 19 Gordon Street, London WC1H 0AH, UK.
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
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13
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Wu M, Wang F, Chen J, Zhang H, Zeng H, Liu J. Interactions of model airborne particulate matter with dipalmitoyl phosphatidylcholine and a clinical surfactant Calsurf. J Colloid Interface Sci 2021; 607:1993-2009. [PMID: 34798708 DOI: 10.1016/j.jcis.2021.09.193] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 09/29/2021] [Accepted: 09/30/2021] [Indexed: 12/31/2022]
Abstract
HYPOTHESIS Lung surfactant protects lung tissue and reduces the surface tension in the alveoli during respiration. Particulate matter with an aerodynamic diameter of less than 2.5 μm (PM2.5), which invades primely through inhalation, can deposit on and interact with the surfactant layer, leading to changes in the biophysical and morphological properties of the lung surfactant. EXPERIMENTS Langmuir monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) and clinical surfactant Calsurf were investigated with a PM2.5 model injected into the water subphase, which were characterized by surface pressure-area isotherms, Brewster angle microscopy, atomic force microscopy, fluorescent microscopy, and x-ray photoelectron spectroscopy. The binding between DPPC/Calsurf and PM2.5 was studied using isothermal titration calorimetry. FINDINGS PM2.5 induced the expansion of the monolayers at low surface pressure (п) and film condensation at high п. Aggregation of PM2.5 mainly occurred at the interface of liquid expanded/liquid condensed (LE/LC) phases. PM2.5 led to slimmer and ramified LC domains on DPPC and the reduction of nano-sized condensed domains on Calsurf. Both DPPC and Calsurf showed fast binding with PM2.5 through complex binding modes attributed to the heterogeneity and amphiphilic property of PM2.5. This study improves the fundamental understanding of PM2.5-lung surfactant interaction and shows useful implications of the toxicity of PM2.5 through respiration process.
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Affiliation(s)
- Min Wu
- The Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510700, China; Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Feifei Wang
- The Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510700, China; Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Jingsi Chen
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Hao Zhang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Hongbo Zeng
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada.
| | - Jifang Liu
- The Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510700, China.
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14
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Loh D, Reiter RJ. Melatonin: Regulation of Biomolecular Condensates in Neurodegenerative Disorders. Antioxidants (Basel) 2021; 10:1483. [PMID: 34573116 PMCID: PMC8465482 DOI: 10.3390/antiox10091483] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/10/2021] [Accepted: 09/13/2021] [Indexed: 12/12/2022] Open
Abstract
Biomolecular condensates are membraneless organelles (MLOs) that form dynamic, chemically distinct subcellular compartments organizing macromolecules such as proteins, RNA, and DNA in unicellular prokaryotic bacteria and complex eukaryotic cells. Separated from surrounding environments, MLOs in the nucleoplasm, cytoplasm, and mitochondria assemble by liquid-liquid phase separation (LLPS) into transient, non-static, liquid-like droplets that regulate essential molecular functions. LLPS is primarily controlled by post-translational modifications (PTMs) that fine-tune the balance between attractive and repulsive charge states and/or binding motifs of proteins. Aberrant phase separation due to dysregulated membrane lipid rafts and/or PTMs, as well as the absence of adequate hydrotropic small molecules such as ATP, or the presence of specific RNA proteins can cause pathological protein aggregation in neurodegenerative disorders. Melatonin may exert a dominant influence over phase separation in biomolecular condensates by optimizing membrane and MLO interdependent reactions through stabilizing lipid raft domains, reducing line tension, and maintaining negative membrane curvature and fluidity. As a potent antioxidant, melatonin protects cardiolipin and other membrane lipids from peroxidation cascades, supporting protein trafficking, signaling, ion channel activities, and ATPase functionality during condensate coacervation or dissolution. Melatonin may even control condensate LLPS through PTM and balance mRNA- and RNA-binding protein composition by regulating N6-methyladenosine (m6A) modifications. There is currently a lack of pharmaceuticals targeting neurodegenerative disorders via the regulation of phase separation. The potential of melatonin in the modulation of biomolecular condensate in the attenuation of aberrant condensate aggregation in neurodegenerative disorders is discussed in this review.
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Affiliation(s)
- Doris Loh
- Independent Researcher, Marble Falls, TX 78654, USA
| | - Russel J. Reiter
- Department of Cellular and Structural Biology, UT Health Science Center, San Antonio, TX 78229, USA
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15
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Zec N, Mangiapia G, Hendry AC, Barker R, Koutsioubas A, Frielinghaus H, Campana M, Ortega-Roldan JL, Busch S, Moulin JF. Mutually Beneficial Combination of Molecular Dynamics Computer Simulations and Scattering Experiments. MEMBRANES 2021; 11:507. [PMID: 34357157 PMCID: PMC8304056 DOI: 10.3390/membranes11070507] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 06/28/2021] [Accepted: 06/29/2021] [Indexed: 11/17/2022]
Abstract
We showcase the combination of experimental neutron scattering data and molecular dynamics (MD) simulations for exemplary phospholipid membrane systems. Neutron and X-ray reflectometry and small-angle scattering measurements are determined by the scattering length density profile in real space, but it is not usually possible to retrieve this profile unambiguously from the data alone. MD simulations predict these density profiles, but they require experimental control. Both issues can be addressed simultaneously by cross-validating scattering data and MD results. The strengths and weaknesses of each technique are discussed in detail with the aim of optimizing the opportunities provided by this combination.
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Affiliation(s)
- Nebojša Zec
- German Engineering Materials Science Centre (GEMS) at Heinz Maier-Leibnitz Zentrum (MLZ), Helmholtz-Zentrum Hereon, Lichtenbergstr. 1, 85748 Garching bei München, Germany; (N.Z.); (G.M.)
| | - Gaetano Mangiapia
- German Engineering Materials Science Centre (GEMS) at Heinz Maier-Leibnitz Zentrum (MLZ), Helmholtz-Zentrum Hereon, Lichtenbergstr. 1, 85748 Garching bei München, Germany; (N.Z.); (G.M.)
| | - Alex C. Hendry
- School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK; (A.C.H.); (J.L.O.-R.)
| | - Robert Barker
- School of Physical Sciences, University of Kent, Canterbury CT2 7NH, UK;
| | - Alexandros Koutsioubas
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich, Lichtenbergstr. 1, 85748 Garching bei München, Germany; (A.K.); (H.F.)
| | - Henrich Frielinghaus
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich, Lichtenbergstr. 1, 85748 Garching bei München, Germany; (A.K.); (H.F.)
| | - Mario Campana
- ISIS Neutron and Muon Facility, Rutherford Appleton Laboratory, Science & Technology Facilities Council, Didcot OX11 0QX, UK;
| | | | - Sebastian Busch
- German Engineering Materials Science Centre (GEMS) at Heinz Maier-Leibnitz Zentrum (MLZ), Helmholtz-Zentrum Hereon, Lichtenbergstr. 1, 85748 Garching bei München, Germany; (N.Z.); (G.M.)
| | - Jean-François Moulin
- German Engineering Materials Science Centre (GEMS) at Heinz Maier-Leibnitz Zentrum (MLZ), Helmholtz-Zentrum Hereon, Lichtenbergstr. 1, 85748 Garching bei München, Germany; (N.Z.); (G.M.)
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16
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Simon M, Veit M, Osterrieder K, Gradzielski M. Surfactants - Compounds for inactivation of SARS-CoV-2 and other enveloped viruses. Curr Opin Colloid Interface Sci 2021; 55:101479. [PMID: 34149296 PMCID: PMC8196227 DOI: 10.1016/j.cocis.2021.101479] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
We provide here a general view on the interactions of surfactants with viruses, with a particular emphasis on how such interactions can be controlled and employed for inhibiting the infectivity of enveloped viruses, including coronaviruses. The aim is to provide to interested scientists from different fields, including chemistry, physics, biochemistry, and medicine, an overview of the basic properties of surfactants and (corona)viruses, which are relevant to understanding the interactions between the two. Various types of interactions between surfactant and virus are important, and they act on different components of a virus such as the lipid envelope, membrane (envelope) proteins and nucleocapsid proteins. Accordingly, this cannot be a detailed account of all relevant aspects but instead a summary that bridges between the different disciplines. We describe concepts and cover a selection of the relevant literature as an incentive for diving deeper into the relevant material. Our focus is on more recent developments around the COVID-19 pandemic caused by SARS-CoV-2, applications of surfactants against the virus, and on the potential future use of surfactants for pandemic relief. We also cover the most important aspects of the historical development of using surfactants in combatting virus infections. We conclude that surfactants are already playing very important roles in various directions of defence against viruses, either directly, as in disinfection, or as carrier components of drug delivery systems for prophylaxis or treatment. By designing tailor-made surfactants, and consequently, advanced formulations, one can expect more and more effective use of surfactants, either directly as antiviral compounds or as part of more complex formulations.
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Key Words
- AFM, atomic force microscopy
- BVDV, Bovine Viral Diarrhea Virus
- C12E8, dodecyloctaglycol
- CPyC, cetylpyridinium chloride
- DSPC, 1,2-distearoyl-sn-glycero-3-phosphocholine
- Disinfection
- Enveloped viruses
- Flu, influenza virus
- HIV, human immunodeficiency virus
- HSV, herpes simplex virus
- ITC, isothermal titration calorimetry
- Ld, liquid-disordered
- Lipid bilayers
- Lo, liquid-ordered
- PA, phosphatidic acid (anionic)
- PC, phosphatidylcholine (zwitterionic)
- PE, phosphatidylethanolamine (zwitterionic)
- PI, phosphatidylinositol (anionic)
- POPC, 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine
- PS, phosphatidylserine (anionic)
- QUAT, quaternary alkyl ammonium
- RNP, ribonucleoprotein particle
- SAXS, small-angle X-ray scattering
- SDS, sodium dodecyl sulphate
- Surfactant
- TBP, tri-n-butyl phosphate
- TEM, transmission electron microscopy
- Virus inactivation
- cac, critical aggregate concentration
- cmc, critical micelle concentration
- p, packing parameter
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Affiliation(s)
- Miriam Simon
- Dept. of Chemical Engineering and the Russell Berrie Nanotechnolgy Inst. (RBNI), Technion-Israel Institute of Technology, Haifa, IL 3200003, Israel
| | - Michael Veit
- Institut für Virologie, Fachbereich Veterinärmedizin, Freie Universität Berlin, Robert von Ostertag-Straße 7-13, 14163 Berlin, Germany
| | - Klaus Osterrieder
- Institut für Virologie, Fachbereich Veterinärmedizin, Freie Universität Berlin, Robert von Ostertag-Straße 7-13, 14163 Berlin, Germany.,Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong
| | - Michael Gradzielski
- Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Straße des 17. Juni 124, Sekr. TC7, Technische Universität Berlin, D-10623 Berlin, Germany
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17
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Fritsch J, Särchen V, Schneider-Brachert W. Regulation of Death Receptor Signaling by S-Palmitoylation and Detergent-Resistant Membrane Micro Domains-Greasing the Gears of Extrinsic Cell Death Induction, Survival, and Inflammation. Cancers (Basel) 2021; 13:2513. [PMID: 34063813 PMCID: PMC8196677 DOI: 10.3390/cancers13112513] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/18/2021] [Accepted: 05/19/2021] [Indexed: 12/11/2022] Open
Abstract
Death-receptor-mediated signaling results in either cell death or survival. Such opposite signaling cascades emanate from receptor-associated signaling complexes, which are often formed in different subcellular locations. The proteins involved are frequently post-translationally modified (PTM) by ubiquitination, phosphorylation, or glycosylation to allow proper spatio-temporal regulation/recruitment of these signaling complexes in a defined cellular compartment. During the last couple of years, increasing attention has been paid to the reversible cysteine-centered PTM S-palmitoylation. This PTM regulates the hydrophobicity of soluble and membrane proteins and modulates protein:protein interaction and their interaction with distinct membrane micro-domains (i.e., lipid rafts). We conclude with which functional and mechanistic roles for S-palmitoylation as well as different forms of membrane micro-domains in death-receptor-mediated signal transduction were unraveled in the last two decades.
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Affiliation(s)
- Jürgen Fritsch
- Department of Infection Prevention and Infectious Diseases, University Hospital Regensburg, Franz-Josef-Strauß-Allee 11, 93053 Regensburg, Germany;
| | - Vinzenz Särchen
- Institute for Experimental Cancer Research in Pediatrics, Goethe-University, 60528 Frankfurt, Germany;
| | - Wulf Schneider-Brachert
- Department of Infection Prevention and Infectious Diseases, University Hospital Regensburg, Franz-Josef-Strauß-Allee 11, 93053 Regensburg, Germany;
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18
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Goh MWS, Tero R. Cholesterol-induced microdomain formation in lipid bilayer membranes consisting of completely miscible lipids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183626. [PMID: 33901442 DOI: 10.1016/j.bbamem.2021.183626] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 11/19/2022]
Abstract
Recently, we reported that a ternary lipid bilayer comprising phosphatidylethanolamine (PE), phosphatidylcholine (PC), which were both derived from chicken egg, and cholesterol (Chol) generates microdomains that function as specific fusion sites for proteoliposomes. Chol-induced microdomain formation in a completely miscible lipid bilayer is an exceptional phenomenon. Numerous studies have elucidated the formation of domains in liquid ordered (Lo) and liquid disordered (Ld) phases of ternary bilayers, which comprise two partially miscible lipids and Chol. Herein, we investigated the composition and mechanism of formation of these unique microdomains in supported lipid bilayers (SLBs) using a fluorescence microscope and an atomic force microscope (AFM). We prepared ternary SLBs using egg-derived PC (eggPC), Chol and three different types of PE: egg-derived PE, 1-palmitoyl-2-oleoyl-PE, and 1,2-didocosahexaenoyl-PE (diDHPE). Fluorescence microscopy observations revealed that fluid and continuous SLBs were formed at PE concentrations (CPE) of ≥6 mol%. Fluorescence recovery after photobleaching measurement revealed that the microdomain was more fluid than the surrounding region that showed typical diffusion coefficient of the Lo phase. The microdomains were observed as depressions in the AFM topographies. Their area fraction (θ) increased with CPE, and diDHPE produced a significantly large θ among the three PEs. The microdomains in the PE+eggPC+Chol-SLBs were rich in polyunsaturated PE and were in the Ld-like phase. Associating eggPC and Chol caused polyunsaturated PE to segregate, resulting in a microdomain formation by conferring the umbrella effect on Chol, entropic effect of disordered acyl chains, and π-π interactions in the hydrophobic core.
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Affiliation(s)
- Melvin Wei Shern Goh
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan
| | - Ryugo Tero
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan.
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19
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Domingues MM, Gomes B, Hollmann A, Santos NC. 25-Hydroxycholesterol Effect on Membrane Structure and Mechanical Properties. Int J Mol Sci 2021; 22:ijms22052574. [PMID: 33806504 PMCID: PMC7961727 DOI: 10.3390/ijms22052574] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 02/08/2021] [Accepted: 02/14/2021] [Indexed: 12/20/2022] Open
Abstract
Cholesterol is responsible for the plasticity of plasma membranes and is involved in physiological and pathophysiological responses. Cholesterol homeostasis is regulated by oxysterols, such as 25-hydroxycholesterol. The presence of 25-hydroxycholesterol at the membrane level has been shown to interfere with several viruses’ entry into their target cells. We used atomic force microscopy to assess the effect of 25-hydroxycholesterol on different properties of supported lipid bilayers with controlled lipid compositions. In particular, we showed that 25-hydroxycholesterol inhibits the lipid-condensing effects of cholesterol, rendering the bilayers less rigid. This study indicates that the inclusion of 25-hydroxycholesterol in plasma membranes or the conversion of part of their cholesterol content into 25-hydroxycholesterol leads to morphological alterations of the sphingomyelin (SM)-enriched domains and promotes lipid packing inhomogeneities. These changes culminate in membrane stiffness variations.
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Affiliation(s)
- Marco M. Domingues
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisbon, Portugal;
- Correspondence: (M.M.D.); (N.C.S.)
| | - Bárbara Gomes
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisbon, Portugal;
| | - Axel Hollmann
- Centro de Investigación en Biofísica Aplicada y Alimentos (CIBAAL), Universidad Nacional de Santiago Del Estero-CONICET, Santiago del Estero 4206, Argentina;
| | - Nuno C. Santos
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisbon, Portugal;
- Correspondence: (M.M.D.); (N.C.S.)
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20
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Abstract
Pore forming proteins are released as water-soluble monomers that form-mostly oligomeric-pores in target membranes. Our understanding of such pore formation relies in part on the direct visualization of their assemblies on and in the membrane. Here, we discuss the application of atomic force microscopy (AFM) to visualize and understand membrane pore formation, illustrated specifically by studies of proteins of the MACPF/CDC superfamily on supported lipid bilayers. Besides detailed protocols, we also point out common imaging artefacts and strategies to avoid them, and briefly outline how AFM can be effectively used in conjunction with other methods.
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Affiliation(s)
- Adrian W Hodel
- Killer Cell Biology Laboratory, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
| | - Katharine Hammond
- National Physical Laboratory, Teddington, United Kingdom; London Centre for Nanotechnology, University College London, London, United Kingdom; Department of Physics & Astronomy, University College London, London, United Kingdom
| | - Bart W Hoogenboom
- London Centre for Nanotechnology, University College London, London, United Kingdom; Department of Physics & Astronomy, University College London, London, United Kingdom.
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21
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Winkler P, Campelo F, Giannotti MI, Garcia-Parajo MF. Impact of Glycans on Lipid Membrane Dynamics at the Nanoscale Unveiled by Planar Plasmonic Nanogap Antennas and Atomic Force Spectroscopy. J Phys Chem Lett 2021; 12:1175-1181. [PMID: 33480693 PMCID: PMC7869103 DOI: 10.1021/acs.jpclett.0c03439] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 01/19/2021] [Indexed: 05/27/2023]
Abstract
Lateral compartmentalization of the plasma membrane is a prominent feature present at multiple spatiotemporal scales that regulates key cellular functions. The extracellular glycocalyx matrix has recently emerged as an important player that modulates the organization of specific receptors and patterns the lipid bilayer itself. However, experimental limitations in investigating its impact on the membrane nanoscale dynamics have hampered detailed studies. Here, we used photonic nanoantenna arrays combined with fluorescence correlation spectroscopy to investigate the influence of hyaluronic acid (HA), a prominent glycosaminoglycan, on the nanoscale organization of mimetic lipid bilayers. Using atomic force microscopy and force spectroscopy, we further correlated our dynamic measurements with the morphology and mechanical properties of bilayers at the nanoscale. Overall, we find that HA has a profound effect on the dynamics, nanoscale organization, and mechanical properties of lipid bilayers that are enriched in sphingolipids and/or cholesterol, such as those present in living cells.
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Affiliation(s)
- Pamina
M. Winkler
- ICFO-Institut
de Ciencies Fotoniques, The Barcelona Institute
of Science and Technology, 08860 Barcelona, Spain
| | - Felix Campelo
- ICFO-Institut
de Ciencies Fotoniques, The Barcelona Institute
of Science and Technology, 08860 Barcelona, Spain
| | - Marina I. Giannotti
- Biomedical
Research Networking Center on Bioengineering, Biomaterials and Nanomedicine
(CIBER-BBN), 28029 Madrid, Spain
- Institut
de Bioenginyeria de Catalunya (IBEC), The
Barcelona Institute of Science
and Technology, 08860 Barcelona, Spain
- Universitat
de Barcelona (UB), 08007 Barcelona, Spain
| | - Maria F. Garcia-Parajo
- ICFO-Institut
de Ciencies Fotoniques, The Barcelona Institute
of Science and Technology, 08860 Barcelona, Spain
- ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
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22
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Soteriou C, Kalli AC, Connell SD, Tyler AII, Thorne JL. Advances in understanding and in multi-disciplinary methodology used to assess lipid regulation of signalling cascades from the cancer cell plasma membrane. Prog Lipid Res 2020; 81:101080. [PMID: 33359620 DOI: 10.1016/j.plipres.2020.101080] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 12/18/2020] [Accepted: 12/18/2020] [Indexed: 12/31/2022]
Abstract
The lipid bilayer is a functional component of cells, forming a stable platform for the initiation of key biological processes, including cell signalling. There are distinct changes in the lipid composition of cell membranes during oncogenic transformation resulting in aberrant activation and inactivation of signalling transduction pathways. Studying the role of the cell membrane in cell signalling is challenging, since techniques are often limited to by timescale, resolution, sensitivity, and averaging. To overcome these limitations, combining 'computational', 'wet-lab' and 'semi-dry' approaches offers the best opportunity to resolving complex biological processes involved in membrane organisation. In this review, we highlight analytical tools that have been applied for the study of cell signalling initiation from the cancer cell membranes through computational microscopy, biological assays, and membrane biophysics. The cancer therapeutic potential of extracellular membrane-modulating agents, such as cholesterol-reducing agents is also discussed, as is the need for future collaborative inter-disciplinary research for studying the role of the cell membrane and its components in cancer therapy.
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Affiliation(s)
- C Soteriou
- School of Food Science and Nutrition, University of Leeds, Leeds LS29JT, UK; Leeds Institute of Cardiovascular and Metabolic Medicine and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK; Molecular and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - A C Kalli
- Leeds Institute of Cardiovascular and Metabolic Medicine and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - S D Connell
- Molecular and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - A I I Tyler
- School of Food Science and Nutrition, University of Leeds, Leeds LS29JT, UK
| | - J L Thorne
- School of Food Science and Nutrition, University of Leeds, Leeds LS29JT, UK.
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23
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Abstract
Transmembrane proteins involved in metabolic redox reactions and photosynthesis catalyse a plethora of key energy-conversion processes and are thus of great interest for bioelectrocatalysis-based applications. The development of membrane protein modified electrodes has made it possible to efficiently exchange electrons between proteins and electrodes, allowing mechanistic studies and potentially applications in biofuels generation and energy conversion. Here, we summarise the most common electrode modification and their characterisation techniques for membrane proteins involved in biofuels conversion and semi-artificial photosynthesis. We discuss the challenges of applications of membrane protein modified electrodes for bioelectrocatalysis and comment on emerging methods and future directions, including recent advances in membrane protein reconstitution strategies and the development of microbial electrosynthesis and whole-cell semi-artificial photosynthesis.
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24
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Vázquez RF, Ovalle-García E, Antillón A, Ortega-Blake I, Bakás LS, Muñoz-Garay C, Maté SM. Asymmetric bilayers mimicking membrane rafts prepared by lipid exchange: Nanoscale characterization using AFM-Force spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1863:183467. [PMID: 32871116 DOI: 10.1016/j.bbamem.2020.183467] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 08/07/2020] [Accepted: 08/24/2020] [Indexed: 01/03/2023]
Abstract
Sphingolipids-enriched rafts domains are proposed to occur in plasma membranes and to mediate important cellular functions. Notwithstanding, the asymmetric transbilayer distribution of phospholipids that exists in the membrane confers the two leaflets different potentials to form lateral domains as next to no sphingolipids are present in the inner leaflet. How the physical properties of one leaflet can influence the properties of the other and its importance on signal transduction across the membrane are questions still unresolved. In this work, we combined AFM imaging and Force spectroscopy measurements to assess domain formation and to study the nanomechanical properties of asymmetric supported lipid bilayers (SLBs) mimicking membrane rafts. Asymmetric SLBs were formed by incorporating N-palmitoyl-sphingomyelin (16:0SM) into the outer leaflet of preformed 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC)/Cholesterol SLBs through methyl-β-cyclodextrin-mediated lipid exchange. Lipid domains were detected after incorporation of 16:0SM though their phase state varied from gel to liquid ordered (Lo) phase if the procedure was performed at 24 or 37 °C, respectively. When comparing symmetric and asymmetric Lo domains, differences in size and morphology were observed, with asymmetric domains being smaller and more interconnected. Both types of Lo domains showed similar mechanical stability in terms of rupture forces and Young's moduli. Notably, force curves in asymmetric domains presented two rupture events that could be attributed to the sequential rupture of a liquid disordered (Ld) and a Lo phase. Interleaflet coupling in asymmetric Lo domains could also be inferred from those measurements. The experimental approach outlined here would significantly enhance the applicability of membrane models.
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Affiliation(s)
- Romina F Vázquez
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), CCT- La Plata, CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, 1900 La Plata, Argentina; Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 y 115, 1900 La Plata, Argentina.
| | - Erasmo Ovalle-García
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, 62210 Cuernavaca, México
| | - Armando Antillón
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, 62210 Cuernavaca, México
| | - Iván Ortega-Blake
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, 62210 Cuernavaca, México
| | - Laura S Bakás
- Centro de Investigación en Proteínas Vegetales (CIProVe), Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 y 115, 1900 La Plata, Argentina
| | - Carlos Muñoz-Garay
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, 62210 Cuernavaca, México
| | - Sabina M Maté
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), CCT- La Plata, CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, 1900 La Plata, Argentina.
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25
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Hammond K, Ryadnov MG, Hoogenboom BW. Atomic force microscopy to elucidate how peptides disrupt membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1863:183447. [PMID: 32835656 DOI: 10.1016/j.bbamem.2020.183447] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/30/2020] [Accepted: 08/13/2020] [Indexed: 12/24/2022]
Abstract
Atomic force microscopy is an increasingly attractive tool to study how peptides disrupt membranes. Often performed on reconstituted lipid bilayers, it provides access to time and length scales that allow dynamic investigations with nanometre resolution. Over the last decade, AFM studies have enabled visualisation of membrane disruption mechanisms by antimicrobial or host defence peptides, including peptides that target malignant cells and biofilms. Moreover, the emergence of high-speed modalities of the technique broadens the scope of investigations to antimicrobial kinetics as well as the imaging of peptide action on live cells in real time. This review describes how methodological advances in AFM facilitate new insights into membrane disruption mechanisms.
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Affiliation(s)
- Katharine Hammond
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK; London Centre for Nanotechnology, University College London, London WC1H 0AH, UK; Department of Physics & Astronomy, University College London, London WC1E 6BT, UK.
| | - Maxim G Ryadnov
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK; Department of Physics, King's College London, Strand Lane, London WC2R 2LS, UK.
| | - Bart W Hoogenboom
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK; Department of Physics & Astronomy, University College London, London WC1E 6BT, UK.
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26
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Sarmento MJ, Ricardo JC, Amaro M, Šachl R. Organization of gangliosides into membrane nanodomains. FEBS Lett 2020; 594:3668-3697. [DOI: 10.1002/1873-3468.13871] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 06/11/2020] [Accepted: 06/15/2020] [Indexed: 01/04/2023]
Affiliation(s)
- Maria J. Sarmento
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences Prague 8 Czech Republic
| | - Joana C. Ricardo
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences Prague 8 Czech Republic
| | - Mariana Amaro
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences Prague 8 Czech Republic
| | - Radek Šachl
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences Prague 8 Czech Republic
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27
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Kikuchi Y, Obana N, Toyofuku M, Kodera N, Soma T, Ando T, Fukumori Y, Nomura N, Taoka A. Diversity of physical properties of bacterial extracellular membrane vesicles revealed through atomic force microscopy phase imaging. NANOSCALE 2020; 12:7950-7959. [PMID: 32232238 DOI: 10.1039/c9nr10850e] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Bacteria release nanometer-scale extracellular membrane vesicles (MVs) to mediate a variety of biological processes. We analyzed individual MVs under physiological conditions by phase imaging of high-speed atomic force microscopy to assess the physiological heterogeneity of MVs isolated from bacterial cultures. Phase imaging makes it possible to map the physical properties of an individual, fragile MV in an isolated MV population containing a broad variety of vesicle diameters, from 20 to 150 nm. We also developed a method for quantitatively comparing the physical properties of MVs among samples. This allowed for the comparison of the physical properties of MVs isolated from different bacterial species. We compared bacterial MVs isolated from four bacterial species and artificially synthesized liposomes. We demonstrate that each bacterial species generates physically heterogeneous types of MVs, unlike the physical homogeneity displayed by liposomes. These results indicate that the physical heterogeneity of bacterial MVs is mainly caused by compositional differences mediated through biological phenomena and could be unique to each species. We provide a new methodology using phase imaging that would pave the way for single-vesicle analysis of extracellular vesicles of a broad size range.
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Affiliation(s)
- Yousuke Kikuchi
- Institute of Science and Engineering, Kanazawa university, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan.
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28
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Goodchild JA, Walsh DL, Connell SD. Nanoscale Substrate Roughness Hinders Domain Formation in Supported Lipid Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:15352-15363. [PMID: 31626551 DOI: 10.1021/acs.langmuir.9b01990] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Supported lipid bilayers are model membranes formed at solid substrate surfaces. This architecture renders the membrane experimentally accessible to surface-sensitive techniques used to study their properties, including atomic force microscopy, optical fluorescence microscopy, quartz crystal microbalance, and X-ray/neutron reflectometry, and allows integration with technology for potential biotechnological applications such as drug screening devices. The experimental technique often dictates substrate choice or treatment, and it is anecdotally recognized that certain substrates are suitable for a particular experiment, but the exact influence of the substrate has not been comprehensively investigated. Here, we study the behavior of a simple model bilayer, phase-separating on a variety of commonly used substrates, including glass, mica, silicon, and quartz, with drastically different results. The distinct micron-scale domains observed on mica, identical to those seen in free-floating giant unilamellar vesicles, are reduced to nanometer-scale domains on glass and quartz. The mechanism for the arrest of domain formation is investigated, and the most likely candidate is nanoscale surface roughness, acting as a drag on the hydrodynamic motion of small domains during phase separation. Evidence was found that the physicochemical properties of the surface have a mediating effect, most likely because of the changes in the lubricating interstitial water layer between the surface and bilayer.
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Affiliation(s)
- James A Goodchild
- School of Physics and Astronomy , University of Leeds , Leeds LS2 9JT , U.K
| | - Danielle L Walsh
- School of Physics and Astronomy , University of Leeds , Leeds LS2 9JT , U.K
| | - Simon D Connell
- School of Physics and Astronomy , University of Leeds , Leeds LS2 9JT , U.K
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29
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Connell SD, Heath GR, Goodchild JA. Quantitative Analysis of Structure and Dynamics in AFM Images of Lipid Membranes. Methods Mol Biol 2019; 1886:29-44. [PMID: 30374860 DOI: 10.1007/978-1-4939-8894-5_2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
AFM is now established as a powerful and direct technique for studying lipid membranes, and is highly complementary with other techniques. It is the only method for direct imaging and mechanical probing of lipid phase structure in a liquid environment down to the nanometer level. In order to understand the structure, function, and interactions of membranes at this level, we must be able to reliably and quantitatively measure the AFM images. Here we describe the methods used to process and analyze AFM images of phase-separated supported lipid bilayers . This initially takes a static approach, where we simply quantify the % of domain area, number of domains, and morphology, and quantify how many images must be taken to obtain reliable statistics. We then look at dynamics, describing the methods we use to study the nanometer scale motion of the domain perimeter as observed using Fast Scan AFM, and hence extract a quantitative line tension.
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Affiliation(s)
- Simon D Connell
- Molecular and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, Leeds, UK.
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK.
| | - George R Heath
- Molecular and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, Leeds, UK
- Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - James A Goodchild
- Molecular and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, Leeds, UK
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30
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Cebecauer M, Amaro M, Jurkiewicz P, Sarmento MJ, Šachl R, Cwiklik L, Hof M. Membrane Lipid Nanodomains. Chem Rev 2018; 118:11259-11297. [PMID: 30362705 DOI: 10.1021/acs.chemrev.8b00322] [Citation(s) in RCA: 128] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Lipid membranes can spontaneously organize their components into domains of different sizes and properties. The organization of membrane lipids into nanodomains might potentially play a role in vital functions of cells and organisms. Model membranes represent attractive systems to study lipid nanodomains, which cannot be directly addressed in living cells with the currently available methods. This review summarizes the knowledge on lipid nanodomains in model membranes and exposes how their specific character contrasts with large-scale phase separation. The overview on lipid nanodomains in membranes composed of diverse lipids (e.g., zwitterionic and anionic glycerophospholipids, ceramides, glycosphingolipids) and cholesterol aims to evidence the impact of chemical, electrostatic, and geometric properties of lipids on nanodomain formation. Furthermore, the effects of curvature, asymmetry, and ions on membrane nanodomains are shown to be highly relevant aspects that may also modulate lipid nanodomains in cellular membranes. Potential mechanisms responsible for the formation and dynamics of nanodomains are discussed with support from available theories and computational studies. A brief description of current fluorescence techniques and analytical tools that enabled progress in lipid nanodomain studies is also included. Further directions are proposed to successfully extend this research to cells.
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Affiliation(s)
- Marek Cebecauer
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Mariana Amaro
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Piotr Jurkiewicz
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Maria João Sarmento
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Radek Šachl
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Lukasz Cwiklik
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
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31
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Tero R, Fukumoto K, Motegi T, Yoshida M, Niwano M, Hirano-Iwata A. Formation of Cell Membrane Component Domains in Artificial Lipid Bilayer. Sci Rep 2017; 7:17905. [PMID: 29263355 PMCID: PMC5738377 DOI: 10.1038/s41598-017-18242-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 12/07/2017] [Indexed: 12/31/2022] Open
Abstract
The lipid bilayer environment around membrane proteins strongly affects their structure and functions. Here, we aimed to study the fusion of proteoliposomes (PLs) derived from cultured cells with an artificial lipid bilayer membrane and the distribution of the PL components after the fusion. PLs, which were extracted as a crude membrane fraction from Chinese hamster ovary (CHO) cells, formed isolated domains in a supported lipid bilayer (SLB), comprising phosphatidylcholine (PC), phosphatidylethanolamine (PE), and cholesterol (Chol), after the fusion. Observation with a fluorescence microscope and an atomic force microscope showed that the membrane fusion occurred selectively at microdomains in the PC + PE + Chol-SLB, and that almost all the components of the PL were retained in the domain. PLs derived from human embryonic kidney 293 (HEK) cells also formed isolated domains in the PC + PE + Chol-SLB, but their fusion kinetics was different from that of the CHO-PLs. We attempted to explain the mechanism of the PL-SLB fusion and the difference between CHO- and HEK-PLs, based on a kinetic model. The domains that contained the whole cell membrane components provided environments similar to that of natural cell membranes, and were thus effective for studying membrane proteins using artificial lipid bilayer membranes.
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Affiliation(s)
- Ryugo Tero
- Department of Environmental and Life Sciences, Toyohashi University of Technology, Toyohashi, Aichi, 441-8580, Japan. .,Electronics-Inspired Interdisciplinary Research Institute, Toyohashi University of Technology, Toyohashi, Aichi, 441-8580, Japan.
| | - Kohei Fukumoto
- Department of Environmental and Life Sciences, Toyohashi University of Technology, Toyohashi, Aichi, 441-8580, Japan
| | - Toshinori Motegi
- Electronics-Inspired Interdisciplinary Research Institute, Toyohashi University of Technology, Toyohashi, Aichi, 441-8580, Japan.,Division of Molecular Science, Faculty of Science and Technology, Gunma University, Kiryu, Gunma, 376-8515, Japan
| | - Miyu Yoshida
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Miyagi, 980-8577, Japan
| | - Michio Niwano
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Miyagi, 980-8577, Japan.,Kansei Fukushi Research Institute, Tohoku Fukushi University, Sendai, Miyagi, 989-3201, Japan
| | - Ayumi Hirano-Iwata
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Miyagi, 980-8577, Japan.,Advanced Institute for Materials Research, Tohoku University, Sendai, Miyagi, 980-8577, Japan
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32
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Avakyan N, Conway JW, Sleiman HF. Long-Range Ordering of Blunt-Ended DNA Tiles on Supported Lipid Bilayers. J Am Chem Soc 2017; 139:12027-12034. [PMID: 28783358 DOI: 10.1021/jacs.7b06572] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Nicole Avakyan
- Department of Chemistry, McGill University, 801
Sherbrooke Street West, Montreal QC H3A 0B8, Canada
| | - Justin W. Conway
- Department of Chemistry, McGill University, 801
Sherbrooke Street West, Montreal QC H3A 0B8, Canada
| | - Hanadi F. Sleiman
- Department of Chemistry, McGill University, 801
Sherbrooke Street West, Montreal QC H3A 0B8, Canada
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33
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Heberle FA, Pabst G. Complex biomembrane mimetics on the sub-nanometer scale. Biophys Rev 2017; 9:353-373. [PMID: 28717925 PMCID: PMC5578918 DOI: 10.1007/s12551-017-0275-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 06/26/2017] [Indexed: 12/12/2022] Open
Abstract
Biomimetic lipid vesicles are indispensable tools for gaining insight into the biophysics of cell physiology on the molecular level. The level of complexity of these model systems has steadily increased, and now spans from domain-forming lipid mixtures to asymmetric lipid bilayers. Here, we review recent progress in the development and application of elastic neutron and X-ray scattering techniques for studying these systems in situ and under physiologically relevant conditions on the nanometer to sub-nanometer length scales. In particular, we focus on: (1) structural details of coexisting liquid-ordered and liquid-disordered domains, including their thickness and lipid packing mismatch as a function of a size transition from nanoscopic to macroscopic domains; (2) membrane-mediated protein partitioning into lipid domains; (3) the role of the aqueous medium in tuning interactions between membranes and domains; and (4) leaflet-specific structure in asymmetric bilayers and passive lipid flip-flop.
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Affiliation(s)
- Frederick A Heberle
- The Bredesen Center, University of Tennessee, Knoxville, TN, 37996, USA.,Joint Institute for Biological Sciences and Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Georg Pabst
- Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, University of Graz, 8010, Graz, Austria. .,BioTechMed-Graz, 8010, Graz, Austria.
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34
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C R, Basu JK. Emergence of compositionally tunable nanoscale dynamical heterogeneity in model binary lipid biomembranes. SOFT MATTER 2017; 13:4598-4606. [PMID: 28604915 DOI: 10.1039/c7sm00581d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
While the existence of nanoscale dynamical heterogeneity in biological membranes has been suggested to act as an active functional platform for enabling various cellular processes like signal transduction and viral or bacterial entry, it has been extremely difficult to detect the existence of such domains. Model lipid bilayer membranes have been widely used to detect such dynamical heterogeneity in order to avoid complications arising from the compositional heterogeneity of cellular membranes. However, even in model biological membranes the issue of nanoscale lipid dynamics has remained controversial and unresolved due to the difficulty of detecting the existence of such dynamical heterogeneity on the scale of 10-300 nm. Here we report direct evidence of nanoscale lipid dynamical heterogeneity in model binary lipid bilayer membranes using a combination of super-resolution stimulated emission depletion (STED) microscopy and fluorescence correlation spectroscopy (FCS). We control the phase behavior of the lipid bilayers by varying their composition and discuss how this leads to the emergence of dynamical lipid domains on the scale of 80-150 nm, which is also dependent on the lipid phase in which such dynamics are observed. Notably, our work shows that the presence of cholesterol is not required for the existence of such domains even in fluid like bilayers, as has been widely believed, and specifies the minimal conditions required for the emergence of such dynamical heterogeneity in cellular membranes. Our work will thus not only be of great significance towards understanding the nanoscale dynamic organizing principles of cellular membranes but could also be useful in understanding the dynamics of related soft matter systems and nanoparticle-cell membrane interactions.
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Affiliation(s)
- Roobala C
- Department of Physics, Indian Institute of Science, Bangalore, 560 012, India.
| | - Jaydeep K Basu
- Department of Physics, Indian Institute of Science, Bangalore, 560 012, India.
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35
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Aufderhorst-Roberts A, Chandra U, Connell SD. Three-Phase Coexistence in Lipid Membranes. Biophys J 2017; 112:313-324. [PMID: 28122217 PMCID: PMC5266263 DOI: 10.1016/j.bpj.2016.12.025] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 11/25/2016] [Accepted: 12/12/2016] [Indexed: 01/01/2023] Open
Abstract
Phospholipid ternary systems are useful model systems for understanding lipid-lipid interactions and their influence on biological properties such as cell signaling and protein translocation. Despite extensive studies, there are still open questions relating to membrane phase behavior, particularly relating to a proposed state of three-phase coexistence, due to the difficulty in clearly distinguishing the three phases. We look in and around the region of the phase diagram where three phases are expected and use a combination of different atomic force microscopy (AFM) modes to present the first images of three coexisting lipid phases in biomimetic cell lipid membranes. Domains form through either nucleation or spinodal decomposition dependent upon composition, with some exhibiting both mechanisms in different domains simultaneously. Slow cooling rates are necessary to sufficiently separate mixtures with high proportions of lo and lβ phase. We probe domain heights and mechanical properties and demonstrate that the gel (lβ) domains have unusually low structural integrity in the three-phase region. This finding supports the hypothesis of a “disordered gel” state that has been proposed from NMR studies of similar systems, where the addition of small amounts of cholesterol was shown to disrupt the regular packing of the lβ state. We use NMR data from the literature on chain disorder in different mixtures and estimate an expected step height that is in excellent agreement with the AFM data. Alternatively, the disordered solid phase observed here and in the wider literature could be explained by the lβ phase being out of equilibrium, in a surface kinetically trapped state. This view is supported by the observation of unusual growth of nucleated domains, which we term “tree-ring growth,” reflecting compositional heterogeneity in large disordered lβ phase domains.
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Affiliation(s)
| | - Udayan Chandra
- School of Physics and Astronomy, University of Leeds, Leeds, United Kingdom
| | - Simon D Connell
- School of Physics and Astronomy, University of Leeds, Leeds, United Kingdom.
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36
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Danial JSH, Cronin B, Mallik C, Wallace MI. On demand modulation of lipid composition in an individual bilayer. SOFT MATTER 2017; 13:1788-1793. [PMID: 28165095 DOI: 10.1039/c6sm01774f] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Changes in local lipid composition are thought to play a key role in regulating many complex cellular processes. By studying lipid organization in artificial lipid bilayers the physical principles underlying these process can be studied in detail. However, such in vitro measurements are often hindered by heterogeneities in the lipid composition of individual bilayers prepared by current bulk methods. Here, the lipid composition of an individual droplet interface bilayer is varied by lipid titration into the bilayer from the oil phase in a microfluidic device. Control of lipid composition allows the reversible switching between single- and two-phase regions and sampling of specific lipid compositions in an individual bilayer. This method enables controlled modulation of composition-sensitive processes in a single lipid membrane.
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Affiliation(s)
- John S H Danial
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Bríd Cronin
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Chandini Mallik
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
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37
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Almonte L, Colchero J. True non-contact atomic force microscopy imaging of heterogeneous biological samples in liquids: topography and material contrast. NANOSCALE 2017; 9:2903-2915. [PMID: 28181615 DOI: 10.1039/c6nr07967a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The present work analyses how the tip-sample interaction signals critically determine the operation of an Atomic Force Microscope (AFM) set-up immersed in liquid. On heterogeneous samples, the conservative tip-sample interaction may vary significantly from point to point - in particular from attractive to repulsive - rendering correct feedback very challenging. Lipid membranes prepared on a mica substrate are analyzed as reference samples which are locally heterogeneous (material contrast). The AFM set-up is operated dynamically at low oscillation amplitude and all available experimental data signals - the normal force, as well as the amplitude and frequency - are recorded simultaneously. From the analysis of how the dissipation (oscillation amplitude) and the conservative interaction (normal force and resonance frequency) vary with the tip-sample distance we conclude that dissipation is the only appropriate feedback source for stable and correct topographic imaging. The normal force and phase then carry information about the sample composition ("chemical contrast"). Dynamic AFM allows imaging in a non-contact regime where essentially no forces are applied, rendering dynamic AFM a truly non-invasive technique.
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Affiliation(s)
- Lisa Almonte
- Centro de Investigación en Óptica y Nanofísica (CIOyN), Departamento Física, Facultad de Química (Campus Espinardo), Universidad de Murcia, E-30100 Murcia, Spain.
| | - Jaime Colchero
- Centro de Investigación en Óptica y Nanofísica (CIOyN), Departamento Física, Facultad de Química (Campus Espinardo), Universidad de Murcia, E-30100 Murcia, Spain.
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38
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Hasan IY, Mechler A. Analytical approaches to study domain formation in biomimetic membranes. Analyst 2017; 142:3062-3078. [PMID: 28758651 DOI: 10.1039/c7an01038a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Novel characterization methods open new horizons in the study of membrane mixtures.
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Affiliation(s)
- Imad Younus Hasan
- La Trobe Institute for Molecular Science
- La Trobe University
- Melbourne
- Australia
| | - Adam Mechler
- La Trobe Institute for Molecular Science
- La Trobe University
- Melbourne
- Australia
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39
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Ho CS, Khadka NK, Pan J. Sub-ten-nanometer heterogeneity of solid supported lipid membranes determined by solution atomic force microscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:181-8. [PMID: 26551323 DOI: 10.1016/j.bbamem.2015.11.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 10/19/2015] [Accepted: 11/05/2015] [Indexed: 12/18/2022]
Abstract
Visually detecting nanoscopic structures in lipid membranes is important for elucidating lipid-lipid interactions, which are suggested to play a role in mediating membrane rafts. We use solution atomic force microscopy (AFM) to study lateral and normal organization in multicomponent lipid membranes supported by mica substrate. Nanoscopic heterogeneity is observed in a three-component system composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/brain-sphingomyelin (bSM)/cholesterol (Chol). We find sub-ten-nanometer correlation lengths that are used to describe membrane lateral organization. In addition, we find that the correlation length is independent on cholesterol concentration, while the height fluctuation (variation) is not. To explore the mechanism that controls the size of membrane heterogeneity, we extend our study to a four-component system composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/POPC/bSM/Chol. By systematically adjusting the relative amount of DOPC and POPC, we obtain macroscopic-to-nanoscopic size transition of membrane heterogeneity. In contrast to the results from vesicle based fluorescence microscopy, we find that the structural transition is continuous both in the lateral and normal directions. We compare our nanoscopic structures to two theoretical models, and find that both the critical fluctuations and the nanodomain models are not sufficient to account for our solution AFM data. Finally, we propose a nanoheterogeneity model that could serve as the organization principle of the observed nanoscopic structures in multicomponent lipid membranes.
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Affiliation(s)
- Chian Sing Ho
- Department of Physics, University of South Florida, Tampa, FL 33620, USA
| | - Nawal K Khadka
- Department of Physics, University of South Florida, Tampa, FL 33620, USA
| | - Jianjun Pan
- Department of Physics, University of South Florida, Tampa, FL 33620, USA.
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40
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Carravilla P, Nieva JL, Goñi FM, Requejo-Isidro J, Huarte N. Two-photon Laurdan studies of the ternary lipid mixture DOPC:SM:cholesterol reveal a single liquid phase at sphingomyelin:cholesterol ratios lower than 1. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:2808-2817. [PMID: 25658036 DOI: 10.1021/la504251u] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The ternary lipid mixture DOPC:eggSM:cholesterol in excess water has been studied in the form of giant unilamellar vesicles using two-photon fluorescence microscopy. Previous publications based on single-photon fluorescence microscopy had reported heterogeneous phase behavior (phase coexistence) in the region of the triangular phase diagram corresponding to SM:cholesterol molar ratios <1. We have examined this region by two-photon microscopy of Laurdan-labeled mixtures and have found that, under our conditions, only a single liquid phase exists. We have shown that macroscopic phase separation in the above region can be artifactually induced by one-photon excitation of the fluorescent probes and ensuing photooxidation and is prevented using two-photon excitation. The main effect of increasing the concentration of cholesterol in mixtures containing 30 mol % SM was to increase the rigidity of the disordered domains. Increasing the concentration of SM in mixtures containing 20 mol % cholesterol gradually augmented the rigidity of the ordered domains, while the disordered domains reached minimal order at a SM:cholesterol 2.25:1 molar ratio, which then increased again. Moreover, the detailed measurement of Laurdan generalized polarization across the whole phase diagram allowed the representation, for both the single- and two-phase regions, of the gradual variation of membrane lateral packing along the diagram, which we found to be governed largely by SM:cholesterol interactions.
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Affiliation(s)
- Pablo Carravilla
- Unidad de Biofísica (CSIC, UPV/EHU), Barrio de Sarriena s/n, 48490 Leioa, Spain
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41
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Maté S, Busto JV, García-Arribas AB, Sot J, Vazquez R, Herlax V, Wolf C, Bakás L, Goñi FM. N-nervonoylsphingomyelin (C24:1) prevents lateral heterogeneity in cholesterol-containing membranes. Biophys J 2015; 106:2606-16. [PMID: 24940778 DOI: 10.1016/j.bpj.2014.04.054] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 04/04/2014] [Accepted: 04/23/2014] [Indexed: 11/19/2022] Open
Abstract
This study was conducted to explore how the nature of the acyl chains of sphingomyelin (SM) influence its lateral distribution in the ternary lipid mixture SM/cholesterol/1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), focusing on the importance of the hydrophobic part of the SM molecule for domain formation. Atomic force microscopy (AFM) measurements showed that the presence of a double bond in the 24:1 SM molecule in mixtures with cholesterol (CHO) or in pure bilayers led to a decrease in the molecular packing. Confocal microscopy and AFM showed, at the meso- and nanoscales respectively, that unlike 16:0 and 24:0 SM, 24:1 SM does not induce phase segregation in ternary lipid mixtures with DOPC and CHO. This ternary lipid mixture had a nanomechanical stability intermediate between those displayed by liquid-ordered (Lo) and liquid-disordered (Ld) phases, as reported by AFM force spectroscopy measurements, demonstrating that 24:1 SM is able to accommodate both DOPC and CHO, forming a single phase. Confocal experiments on giant unilamellar vesicles made of human, sheep, and rabbit erythrocyte ghosts rich in 24:1 SM and CHO, showed no lateral domain segregation. This study provides insights into how the specific molecular structure of SM affects the lateral behavior and the physical properties of both model and natural membranes. Specifically, the data suggest that unsaturated SM may help to keep membrane lipids in a homogeneous mixture rather than in separate domains.
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Affiliation(s)
- Sabina Maté
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Centro Cientifico Tecnológico La Plata, Consejo Nacional de Investigaciones Científicas y Tecnicas, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina.
| | - Jon V Busto
- Unidad de Biofísica-Centro Mixto, Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bilbao, Spain
| | - Aritz B García-Arribas
- Unidad de Biofísica-Centro Mixto, Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bilbao, Spain
| | - Jesús Sot
- Unidad de Biofísica-Centro Mixto, Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bilbao, Spain
| | - Romina Vazquez
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Centro Cientifico Tecnológico La Plata, Consejo Nacional de Investigaciones Científicas y Tecnicas, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Vanesa Herlax
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Centro Cientifico Tecnológico La Plata, Consejo Nacional de Investigaciones Científicas y Tecnicas, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Claude Wolf
- Groupe de spectrométrie de masse-APLIPID, Université Pierre et Marie Curie, Faculté de Médicine Pierre et Marie Curie, Paris, France
| | - Laura Bakás
- Departamento de Ciencias Biológicas. Facultad de Ciencias Exactas. Universidad Nacional de La Plata, La Plata, Argentina
| | - Félix M Goñi
- Unidad de Biofísica-Centro Mixto, Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bilbao, Spain
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Dols-Perez A, Fumagalli L, Gomila G. Structural and nanomechanical effects of cholesterol in binary and ternary spin-coated single lipid bilayers in dry conditions. Colloids Surf B Biointerfaces 2014; 116:295-302. [DOI: 10.1016/j.colsurfb.2013.12.049] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 11/26/2013] [Accepted: 12/21/2013] [Indexed: 12/24/2022]
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Bernardini C, Stoyanov SD, Arnaudov LN, Cohen Stuart MA. Colloids in Flatland: a perspective on 2D phase-separated systems, characterisation methods, and lineactant design. Chem Soc Rev 2013; 42:2100-29. [DOI: 10.1039/c2cs35269a] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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45
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Wilson RL, Kraft ML. Quantifying the molar percentages of cholesterol in supported lipid membranes by time-of-flight secondary ion mass spectrometry and multivariate analysis. Anal Chem 2012. [PMID: 23199099 DOI: 10.1021/ac301856z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The uneven cholesterol distribution among organelles and within the plasma membrane is postulated to be critical for proper cellular function. To study how interactions between cholesterol and specific lipid species contribute to the uneven cholesterol distribution between and within cellular membranes, model lipid membranes are frequently employed. Although the cholesterol distributions within membranes can be directly imaged without labels by using time-of-flight secondary ion mass spectrometry (TOF-SIMS), quantifying the cholesterol abundance at specific membrane locations in a label-free manner remains a challenge. Here, partial least-squares regression (PLSR) of TOF-SIMS data is used to quantitatively measure the local molar percentage (mol %) of cholesterol within supported lipid membranes. With the use of TOF-SIMS data from lipid membranes of known composition, a PLSR model was constructed that correlated the spectral variation to the mol % cholesterol in the membrane. The PLSR model was then used to measure the mol % cholesterol in test membranes and to measure cholesterol exchange between vesicles and supported lipid membranes. The accuracy of these measurements was assessed by comparison to the mol % cholesterol measured with conventional assays. By using this TOF-SIMS/PLSR approach to quantify the mol % cholesterol with location specificity, a better understanding of how the regional lipid composition influences cholesterol abundance and exchange in membranes may be obtained.
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Affiliation(s)
- Robert L Wilson
- Department of Chemistry, University of Illinois at Urbana-Champaign, 61801, United States
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Lopes SC, Neves CS, Eaton P, Gameiro P. Improved model systems for bacterial membranes from differing species: Theimportance of varying composition in PE/PG/cardiolipin ternary mixtures. Mol Membr Biol 2012; 29:207-17. [DOI: 10.3109/09687688.2012.700491] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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47
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Zhong J, He D. Recent Progress in the Application of Atomic Force Microscopy for Supported Lipid Bilayers. Chemistry 2012; 18:4148-55. [DOI: 10.1002/chem.201102831] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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48
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Singh A, Wang H, Silva LC, Na C, Prieto M, Futerman AH, Luberto C, Del Poeta M. Methylation of glycosylated sphingolipid modulates membrane lipid topography and pathogenicity of Cryptococcus neoformans. Cell Microbiol 2012; 14:500-16. [PMID: 22151739 DOI: 10.1111/j.1462-5822.2011.01735.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In previous studies we showed that the replication of Cryptococcus neoformans in the lung environment is controlled by the glucosylceramide (GlcCer) synthase gene (GCS1), which synthesizes the membrane sphingolipid GlcCer from the C9-methyl ceramide. Here, we studied the effect of the mutation of the sphingolipid C9 methyltransferase gene (SMT1), which adds a methyl group to position 9 of the sphingosine backbone of ceramide. The C. neoformans Δsmt1 mutant does not make C9-methyl ceramide and, thus, any methylated GlcCer. However, it accumulates demethylated ceramide and demethylated GlcCer. The Δsmt1 mutant loses more than 80% of its virulence compared with the wild type and the reconstituted strain. Interestingly, growth of C. neoformans Δsmt1 in the lung was decreased and C. neoformans cells were contained in lung granulomas, which significantly reduced the rate of their dissemination to the brain reducing the onset of meningoencephalitis. Thus, using fluorescent spectroscopy and atomic force microscopy we compared the wild type and Δsmt1 mutant and found that the altered membrane composition and GlcCer structure affects fungal membrane rigidity, suggesting that specific sphingolipid structures are required for proper fungal membrane organization and integrity. Therefore, we propose that the physical structure of the plasma membrane imparted by specific classes of sphingolipids represents a critical factor for the ability of the fungus to establish virulence.
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Affiliation(s)
- Arpita Singh
- Biochemistry & Molecular Biology, Medical University of South Carolina, Charleston, South Carolina, USA
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49
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Lista M, Areephong J, Orentas E, Charbonnaz P, Sakai N, Matile S. Engineering antiparallel charge-transfer cascades into supramolecular n/p-heterojunction photosystems: Toward directional self-sorting on surfaces. Faraday Discuss 2012; 155:63-77; discussion 103-14. [DOI: 10.1039/c1fd00072a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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50
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Sheikh KH, Jarvis SP. Crystalline hydration structure at the membrane-fluid interface of model lipid rafts indicates a highly reactive boundary region. J Am Chem Soc 2011; 133:18296-303. [PMID: 21991934 DOI: 10.1021/ja2068142] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The fluid mosaic model of biological membranes is that of a two-dimensional lipid bilayer in which both lipids and associated membrane proteins diffuse freely. More recently, the raft hypothesis proposed that membranes contain small, dynamic, functional domains (rafts), which act as platforms for membrane protein attachment and interaction. Although experimental evidence supporting the raft hypothesis is growing, very little is known of the structure of the membrane-fluid interface of lipid raft systems. Here, we report the direct submolecular-scale imaging of model raft membranes using ultrahigh resolution atomic force microscopy. We characterize the heterogeneous nature of crystalline hydration layers at the membrane-fluid interface. The association of crystalline hydration layers with raft membranes would significantly affect the mechanism and kinetics of both inter-raft interactions and those between rafts and external biomolecules, and therefore this finding has important implications for membrane biology.
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Affiliation(s)
- Khizar H Sheikh
- Nanoscale Function Group, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland.
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