1
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Gamage YI, Pan J. Nanoscale Perturbations of Lipid Bilayers Induced by Magainin 2: Insights from AFM Imaging and Force Spectroscopy. Chem Phys Lipids 2024; 263:105421. [PMID: 39067642 DOI: 10.1016/j.chemphyslip.2024.105421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2024] [Revised: 07/13/2024] [Accepted: 07/25/2024] [Indexed: 07/30/2024]
Abstract
This study explores the impact of the antimicrobial peptide magainin 2 (Mag2) on lipid bilayers with varying compositions. We employed high-resolution atomic force microscopy (AFM) to reveal a dynamic spectrum of structural changes induced by Mag2. Our AFM imaging unveiled distinct structural alterations in zwitterionic POPC bilayers upon Mag2 exposure, notably the formation of nanoscale depressions within the bilayer surface, which we term as "surface pores" to differentiate them from transmembrane pores. These surface pores are characterized by a limited depth that does not appear to fully traverse the bilayer and reach the opposing leaflet. Additionally, our AFM-based force spectroscopy investigation on POPC bilayers revealed a reduction in bilayer puncture force (FP) and Young's modulus (E) upon Mag2 interaction, indicating a weakening of bilayer stability and increased flexibility, which may facilitate peptide insertion. The inclusion of anionic POPG into POPC bilayers elucidated its modulatory effects on Mag2 activity, highlighting the role of lipid composition in peptide-bilayer interactions. In contrast to surface pores, Mag2 treatment of E. coli total lipid extract bilayers resulted in increased surface roughness, which we describe as a fluctuation-like morphology. We speculate that the weaker cohesive interactions between heterogeneous lipids in E. coli bilayers may render them more susceptible to Mag2-induced perturbations. This could lead to widespread disruptions manifested as surface fluctuations throughout the bilayer, rather than the formation of well-defined pores. Together, our findings of nanoscale bilayer perturbations provide useful insights into the molecular mechanisms governing Mag2-membrane interactions.
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Affiliation(s)
| | - Jianjun Pan
- Department of Physics, University of South Florida, Tampa, FL 33620.
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2
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Tang Y, Zhang Y, Zhang D, Liu Y, Nussinov R, Zheng J. Exploring pathological link between antimicrobial and amyloid peptides. Chem Soc Rev 2024. [PMID: 39041297 DOI: 10.1039/d3cs00878a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
Amyloid peptides (AMYs) and antimicrobial peptides (AMPs) are considered as the two distinct families of peptides, characterized by their unique sequences, structures, biological functions, and specific pathological targets. However, accumulating evidence has revealed intriguing pathological connections between these peptide families in the context of microbial infection and neurodegenerative diseases. Some AMYs and AMPs share certain structural and functional characteristics, including the ability to self-assemble, the presence of β-sheet-rich structures, and membrane-disrupting mechanisms. These shared features enable AMYs to possess antimicrobial activity and AMPs to acquire amyloidogenic properties. Despite limited studies on AMYs-AMPs systems, the cross-seeding phenomenon between AMYs and AMPs has emerged as a crucial factor in the bidirectional communication between the pathogenesis of neurodegenerative diseases and host defense against microbial infections. In this review, we examine recent developments in the potential interplay between AMYs and AMPs, as well as their pathological implications for both infectious and neurodegenerative diseases. By discussing the current progress and challenges in this emerging field, this account aims to inspire further research and investments to enhance our understanding of the intricate molecular crosstalk between AMYs and AMPs. This knowledge holds great promise for the development of innovative therapies to combat both microbial infections and neurodegenerative disorders.
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Affiliation(s)
- Yijing Tang
- Department of Chemical, Biomolecular, and Corrosion Engineering, The University of Akron, Ohio 44325, USA.
| | - Yanxian Zhang
- Division of Endocrinology and Diabetes, Department of Pediatrics, School of Medicine, Stanford University, Palo Alto, CA 94304, USA
| | - Dong Zhang
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30332, USA
| | - Yonglan Liu
- Cancer Innovation Laboratory, National Cancer Institute, Frederick, MD 21702, USA
| | - Ruth Nussinov
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA.
- Department of Human Molecular Genetics and Biochemistry Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Jie Zheng
- Department of Chemical, Biomolecular, and Corrosion Engineering, The University of Akron, Ohio 44325, USA.
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3
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Gamage YI, Wadumesthri Y, Gutiérrez HR, Voronine DV, Pan J. The impact of transmembrane peptides on lipid bilayer structure and mechanics: A study of the transmembrane domain of the influenza A virus M2 protein. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184373. [PMID: 39047857 DOI: 10.1016/j.bbamem.2024.184373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 05/15/2024] [Accepted: 07/16/2024] [Indexed: 07/27/2024]
Abstract
Transmembrane peptides play important roles in many biological processes by interacting with lipid membranes. This study investigates how the transmembrane domain of the influenza A virus M2 protein, M2TM, affects the structure and mechanics of model lipid bilayers. Atomic force microscopy (AFM) imaging revealed small decreases in bilayer thickness with increasing peptide concentrations. AFM-based force spectroscopy experiments complemented by theoretical model analysis demonstrated significant decreases in bilayer's Young's modulus (E) and lateral area compressibility modulus (KA). This suggests that M2TM disrupts the cohesive interactions between neighboring lipid molecules, leading to a decrease in both the bilayer's resistance to indentation (E) and its ability to resist lateral compression/expansion (KA). The large decreases in bilayer elastic parameters (i.e., E and KA) contrast with small changes in bilayer thickness, implying that bilayer mechanics are not solely dictated by bilayer thickness in the presence of transmembrane peptides. The observed significant reduction in bilayer mechanical properties suggests a softening effect on the bilayer, potentially facilitating membrane curvature generation, a crucial step for M2-mediated viral budding. In parallel, our Raman spectroscopy revealed small but statistically significant changes in hydrocarbon chain vibrational dynamics, indicative of minor disordering in lipid chain conformation. Our findings provide useful insights into the complex interplay between transmembrane peptides and lipid bilayers, highlighting the significance of peptide-lipid interactions in modulating membrane structure, mechanics, and molecular dynamics.
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Affiliation(s)
| | - Yasinthara Wadumesthri
- Department of Physics, University of South Florida, Tampa, FL 33620, United States of America
| | | | - Dmitri V Voronine
- Department of Physics, University of South Florida, Tampa, FL 33620, United States of America
| | - Jianjun Pan
- Department of Physics, University of South Florida, Tampa, FL 33620, United States of America.
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4
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Kumar H, Mandal S, Yadav R, Gupta S, Meena H, Kadu M, Kudawla R, Sharma P, Kaur IP, Maiti S, Ipsen JH, Bhatia T. Bottom-up approach to explore alpha-amylase assisted membrane remodelling. Chem Phys Lipids 2024; 259:105374. [PMID: 38176612 DOI: 10.1016/j.chemphyslip.2023.105374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 12/19/2023] [Accepted: 12/27/2023] [Indexed: 01/06/2024]
Abstract
Soluble alpha-amylases play an important role in the catabolism of polysaccharides. In this work, we show that the malt α -amylase can interact with the lipid membrane and further alter its mechanical properties. Vesicle fluctuation spectroscopy is used for quantitative measurement of the membrane bending rigidity of phosphatidylcholines lipid vesicles from the shape fluctuation based on the whole contour of Giant Unilamellar Vesicles (GUVs). The bending rigidity of the 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine lipid vesicles in water increases significantly with the presence of 0.14 micromolar alpha-amylase (AA) in the exterior solution. It appears that the enzyme present in the external solution interacts with the outer layer of the bilayer membrane, leading to an asymmetry of the solution on either side of the bilayer membrane and altering its elasticity. At AA concentration of 1.5 micromolars and above, changes in the morphology of the GUV membrane are observed. The interaction between AA in the external solution and the external leaflet causes the bilayer membrane to curve spontaneously, leading to the formation of outbuds, giving a positive spontaneous curvature of C0 ≤ 0.05 μm-1 at ≈ 1 mg / ml of the AA concentration. We validate and characterize its concentration-dependent role in stabilizing the membrane curvature. Our findings indicate that the involvement of the enzyme, depending on the concentration, can have a considerable effect on the mechanical characteristics of the membrane.
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Affiliation(s)
- Harshit Kumar
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, Manauli, SAS Nagar, Punjab 140306, India
| | - Sayar Mandal
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, Manauli, SAS Nagar, Punjab 140306, India
| | - Reena Yadav
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, Manauli, SAS Nagar, Punjab 140306, India
| | - Suhasi Gupta
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, Manauli, SAS Nagar, Punjab 140306, India
| | - Hemraj Meena
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, Manauli, SAS Nagar, Punjab 140306, India
| | - Mayur Kadu
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, Manauli, SAS Nagar, Punjab 140306, India
| | - Rajni Kudawla
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, Manauli, SAS Nagar, Punjab 140306, India
| | - Pratibha Sharma
- University Institute of Pharmaceutical Sciences, Punjab University, Sector 14, Chandigarh 160014, Punjab, India
| | - Indu Pal Kaur
- University Institute of Pharmaceutical Sciences, Punjab University, Sector 14, Chandigarh 160014, Punjab, India
| | - Subhabrata Maiti
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, Manauli, SAS Nagar, Punjab 140306, India
| | - John H Ipsen
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej, Odense, 5230 M, Denmark.
| | - Tripta Bhatia
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, Manauli, SAS Nagar, Punjab 140306, India.
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5
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Karal MAS, Billah MM, Ahmed M, Ahamed MK. A review on the measurement of the bending rigidity of lipid membranes. SOFT MATTER 2023; 19:8285-8304. [PMID: 37873600 DOI: 10.1039/d3sm00882g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
This review provides an overview of the latest developments in both experimental and simulation techniques used to assess the bending rigidity of lipid membranes. It places special emphasis on experimental methods that utilize model vesicles to manipulate lipid compositions and other experimental parameters to determine the bending rigidity of the membrane. It also describes two commonly used simulation methods for estimating bending rigidity. The impact of various factors on membrane bending rigidity is summarized, including cholesterol, lipids, salt concentration, surface charge, membrane phase state, peptides, proteins, and polyethylene glycol. These factors are shown to influence the bending rigidity, contributing to a better understanding of the biophysical properties of membranes and their role in biological processes. Furthermore, the review discusses future directions and potential advancements in this research field, highlighting areas where further investigation is required.
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Affiliation(s)
- Mohammad Abu Sayem Karal
- Department of Physics, Bangladesh University of Engineering and Technology, Dhaka 1000, Bangladesh.
| | - Md Masum Billah
- Department of Physics, Jashore University of Science and Technology, Jashore 7408, Bangladesh
| | - Marzuk Ahmed
- Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka 422-8529, Japan
| | - Md Kabir Ahamed
- Radiation, Transport and Waste Safety Division, Bangladesh Atomic Energy Regulatory Authority, Agargaon, Dhaka 1207, Bangladesh
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6
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Pinigin KV, Akimov SA. The Membrane-Mediated Interaction of Liquid-Ordered Lipid Domains in the Presence of Amphipathic Peptides. MEMBRANES 2023; 13:816. [PMID: 37887988 PMCID: PMC10608175 DOI: 10.3390/membranes13100816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 09/08/2023] [Accepted: 09/22/2023] [Indexed: 10/28/2023]
Abstract
The lipid membranes of living cells are composed of a large number of lipid types and can undergo phase separation with the formation of nanometer-scale liquid-ordered lipid domains, also called rafts. Raft coalescence, i.e., the fusion of lipid domains, is involved in important cell processes, such as signaling and trafficking. In this work, within the framework of the theory of elasticity of lipid membranes, we explore how amphipathic peptides adsorbed on lipid membranes may affect the domain-domain fusion processes. We show that the elastic deformations of lipid membranes drive amphipathic peptides to the boundary of lipid domains, which leads to an increase in the average energy barrier of the domain-domain fusion, even if the surface concentration of amphipathic peptides is low and the domain boundaries are only partially occupied by the peptides. This inhibition of the fusion of lipid domains may lead to negative side effects of using amphipathic peptides as antimicrobial agents.
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Affiliation(s)
- Konstantin V. Pinigin
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy Prospekt, 119071 Moscow, Russia
| | - Sergey A. Akimov
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy Prospekt, 119071 Moscow, Russia
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7
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Bashkirov PV, Kuzmin PI, Vera Lillo J, Frolov VA. Molecular Shape Solution for Mesoscopic Remodeling of Cellular Membranes. Annu Rev Biophys 2022; 51:473-497. [PMID: 35239417 PMCID: PMC10787580 DOI: 10.1146/annurev-biophys-011422-100054] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cellular membranes self-assemble from and interact with various molecular species. Each molecule locally shapes the lipid bilayer, the soft elastic core of cellular membranes. The dynamic architecture of intracellular membrane systems is based on elastic transformations and lateral redistribution of these elementary shapes, driven by chemical and curvature stress gradients. The minimization of the total elastic stress by such redistribution composes the most basic, primordial mechanism of membrane curvature-composition coupling (CCC). Although CCC is generally considered in the context of dynamic compositional heterogeneity of cellular membrane systems, in this article we discuss a broader involvement of CCC in controlling membrane deformations. We focus specifically on the mesoscale membrane transformations in open, reservoir-governed systems, such as membrane budding, tubulation, and the emergence of highly curved sites of membrane fusion and fission. We reveal that the reshuffling of molecular shapes constitutes an independent deformation mode with complex rheological properties.This mode controls effective elasticity of local deformations as well as stationary elastic stress, thus emerging as a major regulator of intracellular membrane remodeling.
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Affiliation(s)
- Pavel V Bashkirov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow, Russia
- Department of Molecular and Biological Physics, Moscow Institute of Physics and Technology, Moscow, Russia
| | - Peter I Kuzmin
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia
| | - Javier Vera Lillo
- Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain;
| | - Vadim A Frolov
- Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain;
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain
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8
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Siegel DP. Bicontinuous inverted cubic phase stabilization as an index of antimicrobial and membrane fusion peptide activity. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183815. [PMID: 34748744 DOI: 10.1016/j.bbamem.2021.183815] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/06/2021] [Accepted: 10/29/2021] [Indexed: 02/07/2023]
Abstract
Some antimicrobial peptides (AMPs) and membrane fusion-catalyzing peptides (FPs) stabilize bicontinuous inverted cubic (QII) phases. Previous authors proposed a topological rationale: since AMP-induced pores, fusion intermediates, and QII phases all have negative Gaussian curvature (NGC), peptides which produce NGC in one structure also do it in another. This assumes that peptides change the curvature energy of the lipid membranes. Here I test this with a Helfrich curvature energy model. First, experimentally, I show that lipid systems often used to study peptide NGC have NGC without peptides at higher temperatures. To determine the net effect of an AMP on NGC, the equilibrium phase behavior of the host lipids must be determined. Second, the model shows that AMPs must make large changes in the curvature energy to stabilize AMP-induced pores. Peptide-induced changes in elastic constants affect pores and QII phase differently. Changes in spontaneous curvature affect them in opposite ways. The observed correlation between QII phase stabilization and AMP activity doesn't show that AMPs act by lowering pore curvature energy. A different rationale is proposed. In theory, AMPs could simultaneously stabilize QII phase and pores by drastically changing two particular elastic constants. This could be tested by measuring AMP effects on the individual constants. I propose experiments to do that. Unlike AMPs, FPs must make only small changes in the curvature energy to catalyze fusion. It they act in this way, their fusion activity should correlate with their ability to stabilize QII phases.
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Affiliation(s)
- D P Siegel
- Givaudan Inc., 1199 Edison Drive, Cincinnati, OH 45216, United States of America.
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9
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Gupta M, Weaver DF. Microsecond molecular dynamics studies of cholesterol-mediated myelin sheath degeneration in early Alzheimer's disease. Phys Chem Chem Phys 2021; 24:222-239. [PMID: 34878462 DOI: 10.1039/d1cp03844c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cholesterol-mediated perturbations of membrane structural integrity are key early events in the molecular pathogenesis of Alzheimer's disease (AD). In AD, protein misfolding (proteopathy) and pro-inflammatory conditions (immunopathy) culminate in neuronal death, a process enabled by altered membrane biophysical properties which render neurons more susceptible to proteopathic and immunopathic cytotoxicities. Since cholesterol is a principal neuronal membrane lipid, normal cholesterol homeostasis is central to membrane health; also, since increased cholesterol composition is especially present in neuronal myelin sheath (i.e. brain "white matter"), recent studies have not surprisingly revealed that white matter atrophy precedes the conventional biomarkers of AD (amyloid plaques, tau tangles). Employing extensive microsecond all-atom molecular dynamics simulations, we investigated biophysical and mechanical properties of myelin sheath membrane as a function of cholesterol mole fraction (χCHL). Impaired χCHL modulates multiple bilayer properties, including surface area per lipid (APL), chain order, number and mass density profiles, area compressibility and bending moduli, bilayer thickness, lipid tilt angles, H-bonding interactions and tail interdigitation. The increased orientational ordering of both palmitoyl and oleoyl chains in model healthy myelin sheath (HMS) membranes illustrates the condensing effect of cholesterol. With an increase in χCHL, number density profiles of water tend to attain bulk water number density more quickly, indicating shrinkage in the interfacial region with increasing χCHL. The average tilt value is 11.5° for the C10-C13 angle in cholesterol and 64.2° for the P-N angle in POPC lipids in HMS. These calculations provide a molecular-level understanding of myelin sheath susceptibility to pathology as an early event in the pathogenesis of AD.
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Affiliation(s)
- Mayuri Gupta
- Krembil Research Institute, University Health Network, 60 Leonard Avenue, Toronto, M5T 0S8, Canada.
| | - Donald F Weaver
- Krembil Research Institute, University Health Network, 60 Leonard Avenue, Toronto, M5T 0S8, Canada. .,Departments of Chemistry, Medicine and Pharmaceutical Sciences, University of Toronto, Toronto, ON, M55 3H6, Canada
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10
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Ye S, Li W, Wang H, Zhu L, Wang C, Yang Y. Quantitative Nanomechanical Analysis of Small Extracellular Vesicles for Tumor Malignancy Indication. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2100825. [PMID: 34338437 PMCID: PMC8456224 DOI: 10.1002/advs.202100825] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 05/31/2021] [Indexed: 05/27/2023]
Abstract
The nanomechanical properties of tumor-derived small extracellular vesicles (sEVs) are essential to cancer progression. Here, nanoindentation is utilized on atomic force microscopy (AFM) to quantitatively investigate the nanomechanical properties of human breast cancer cell-derived sEVs at single vesicle level and explore their relationship with tumor malignancy and vesicle size. It is demonstrated that the stiffness of the sEVs results from the combined contribution of the bending modulus and osmotic pressure of the sEVs. The stiffness and osmotic pressure increase with increasing malignancy of the sEVs and decrease with increasing size of the sEVs. The bending modulus decreases with increasing malignancy of the sEVs and is lower in smaller sEVs. This study builds relationship between the nanomechanical signature of the sEV and tumor malignancy, adding information for better understanding cancer mechanobiology.
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Affiliation(s)
- Siyuan Ye
- CAS Key Laboratory of Standardization and Measurement for NanotechnologyCAS Key Laboratory of Biological Effects of Nanomaterials and NanosafetyCAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing100190P. R. China
- University of Chinese Academy of SciencesBeijing100049P. R. China
- Department of ChemistryTsinghua UniversityBeijing100084P. R. China
| | - Wenzhe Li
- CAS Key Laboratory of Standardization and Measurement for NanotechnologyCAS Key Laboratory of Biological Effects of Nanomaterials and NanosafetyCAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing100190P. R. China
- State Key Laboratory of Natural and Biomimetic DrugsSchool of Pharmaceutical SciencesPeking UniversityBeijing100871P. R. China
| | - Huayi Wang
- CAS Key Laboratory of Standardization and Measurement for NanotechnologyCAS Key Laboratory of Biological Effects of Nanomaterials and NanosafetyCAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing100190P. R. China
- University of Chinese Academy of SciencesBeijing100049P. R. China
- Translational Medicine CenterChinese Institute for Brain Research (CIBR)Beijing102206P. R. China
| | - Ling Zhu
- CAS Key Laboratory of Standardization and Measurement for NanotechnologyCAS Key Laboratory of Biological Effects of Nanomaterials and NanosafetyCAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing100190P. R. China
- University of Chinese Academy of SciencesBeijing100049P. R. China
| | - Chen Wang
- CAS Key Laboratory of Standardization and Measurement for NanotechnologyCAS Key Laboratory of Biological Effects of Nanomaterials and NanosafetyCAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing100190P. R. China
- University of Chinese Academy of SciencesBeijing100049P. R. China
| | - Yanlian Yang
- CAS Key Laboratory of Standardization and Measurement for NanotechnologyCAS Key Laboratory of Biological Effects of Nanomaterials and NanosafetyCAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing100190P. R. China
- University of Chinese Academy of SciencesBeijing100049P. R. China
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11
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Single-molecule fluorescence vistas of how lipids regulate membrane proteins. Biochem Soc Trans 2021; 49:1685-1694. [PMID: 34346484 DOI: 10.1042/bst20201074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 07/15/2021] [Accepted: 07/19/2021] [Indexed: 12/17/2022]
Abstract
The study of membrane proteins is undergoing a golden era, and we are gaining unprecedented knowledge on how this key group of proteins works. However, we still have only a basic understanding of how the chemical composition and the physical properties of lipid bilayers control the activity of membrane proteins. Single-molecule (SM) fluorescence methods can resolve sample heterogeneity, allowing to discriminate between the different molecular populations that biological systems often adopt. This short review highlights relevant examples of how SM fluorescence methodologies can illuminate the different ways in which lipids regulate the activity of membrane proteins. These studies are not limited to lipid molecules acting as ligands, but also consider how the physical properties of the bilayer can be determining factors on how membrane proteins function.
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12
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Monasterio BG, Jiménez-Rojo N, García-Arribas AB, Riezman H, Goñi FM, Alonso A. CHO/LY-B cell growth under limiting sphingolipid supply: Correlation between lipid composition and biophysical properties of sphingolipid-restricted cell membranes. FASEB J 2021; 35:e21657. [PMID: 34010474 DOI: 10.1096/fj.202001879rr] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 04/09/2021] [Accepted: 04/26/2021] [Indexed: 11/11/2022]
Abstract
Sphingolipids (SL) are ubiquitous in mammalian cell membranes, yet there is little data on the behavior of cells under SL-restriction conditions. LY-B cells derive from a CHO linein whichserine palmitoyl transferase (SPT), thus de novo SL synthesis, is suppressed, while maintaining the capacity of taking up and metabolizing exogenous sphingoid bases from the culture medium. In this study, LY-B cells were adapted to grow in a fetal bovine serum (FBS)-deficient medium to avoid external uptake of lipids. The lowest FBS concentration that allowed LY-B cell growth, though at a slow rate, under our conditions was 0.04%, that is, 250-fold less than the standard (10%) concentration. Cells grown under limiting SL concentrations remained viable for at least 72 hours. Enriching with sphingomyelin the SL-deficient medium allowed the recovery of growth rates analogous to those of control LY-B cells. Studies including whole cells, plasma membrane preparations, and derived lipid vesicles were carried out. Laurdan fluorescence was recorded to measure membrane molecular order, showing a significant decrease in the rigidity of LY-B cells, not only in plasma membrane but also in whole cell lipid extract, as a result of SL limitation in the growth medium. Plasma membrane preparations and whole cell lipid extracts were also studied using atomic force microscopy in the force spectroscopy mode. Force measurements demonstrated that lower breakthrough forces were required to penetrate samples obtained from SL-poor LY-B cells than those obtained from control cells. Mass-spectroscopic analysis was also a helpful tool to understand the rearrangement undergone by the LY-B cell lipid metabolism. The most abundant SL in LY-B cells, sphingomyelin, decreased by about 85% as a result of SL limitation in the medium, the bioactive lipid ceramide and the ganglioside precursor hexosylceramide decreased similarly, together with cholesterol. Quantitative SL analysis showed that a 250-fold reduction in sphingolipid supply to LY-B cells led only to a sixfold decrease in membrane sphingolipids, underlining the resistance to changes in composition of these cells. Plasma membrane compositions exhibited similar changes, at least qualitatively, as the whole cells with SL restriction. A linear correlation was observed between the sphingomyelin concentration in the membranes, the degree of lipid order as measured by laurdan fluorescence, and membrane breakthrough forces assessed by atomic force microscopy. Smaller, though significant, changes were also detected in glycerophospholipids under SL-restriction conditions.
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Affiliation(s)
- Bingen G Monasterio
- Instituto Biofisika (CSIC, UPV/EHU), Universidad del País Vasco, Leioa, Spain.,Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain
| | - Noemi Jiménez-Rojo
- NCCR Chemical Biology, Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - Aritz B García-Arribas
- Instituto Biofisika (CSIC, UPV/EHU), Universidad del País Vasco, Leioa, Spain.,Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain
| | - Howard Riezman
- NCCR Chemical Biology, Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - Félix M Goñi
- Instituto Biofisika (CSIC, UPV/EHU), Universidad del País Vasco, Leioa, Spain.,Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain
| | - Alicia Alonso
- Instituto Biofisika (CSIC, UPV/EHU), Universidad del País Vasco, Leioa, Spain.,Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain
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13
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Galassi VV, Wilke N. On the Coupling between Mechanical Properties and Electrostatics in Biological Membranes. MEMBRANES 2021; 11:478. [PMID: 34203412 PMCID: PMC8306103 DOI: 10.3390/membranes11070478] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/18/2021] [Accepted: 06/22/2021] [Indexed: 12/24/2022]
Abstract
Cell membrane structure is proposed as a lipid matrix with embedded proteins, and thus, their emerging mechanical and electrostatic properties are commanded by lipid behavior and their interconnection with the included and absorbed proteins, cytoskeleton, extracellular matrix and ionic media. Structures formed by lipids are soft, dynamic and viscoelastic, and their properties depend on the lipid composition and on the general conditions, such as temperature, pH, ionic strength and electrostatic potentials. The dielectric constant of the apolar region of the lipid bilayer contrasts with that of the polar region, which also differs from the aqueous milieu, and these changes happen in the nanometer scale. Besides, an important percentage of the lipids are anionic, and the rest are dipoles or higher multipoles, and the polar regions are highly hydrated, with these water molecules forming an active part of the membrane. Therefore, electric fields (both, internal and external) affects membrane thickness, density, tension and curvature, and conversely, mechanical deformations modify membrane electrostatics. As a consequence, interfacial electrostatics appears as a highly important parameter, affecting the membrane properties in general and mechanical features in particular. In this review we focus on the electromechanical behavior of lipid and cell membranes, the physicochemical origin and the biological implications, with emphasis in signal propagation in nerve cells.
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Affiliation(s)
- Vanesa Viviana Galassi
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza M5500, Argentina;
- Instituto Interdisciplinario de Ciencias Básicas (ICB), Universidad Nacional de Cuyo, CONICET, Mendoza M5500, Argentina
| | - Natalia Wilke
- Departamento de Química Biológica Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba X5000HUA, Argentina
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Universidad Nacional de Córdoba, CONICET, Córdoba X5000HUA, Argentina
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14
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Kelley EG, Butler PD, Nagao M. Collective dynamics in lipid membranes containing transmembrane peptides. SOFT MATTER 2021; 17:5671-5681. [PMID: 33942045 PMCID: PMC10466476 DOI: 10.1039/d1sm00314c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Biological membranes are composed of complex mixtures of lipids and proteins that influence each other's structure and function. The biological activities of many channel-forming peptides and proteins are known to depend on the material properties of the surrounding lipid bilayer. However, less is known about how membrane-spanning channels affect the lipid bilayer properties, and in particular, their collective fluctuation dynamics. Here we use neutron spin echo spectroscopy (NSE) to measure the collective bending and thickness fluctuation dynamics in dimyristoylphosphatidylcholine (di 14 : 0 PC, DMPC) lipid membranes containing two different antimicrobial peptides, alamethicin (Ala) and gramicidin (gD). Ala and gD are both well-studied antimicrobial peptides that form oligomeric membrane-spanning channels with different structures. At low concentrations, the peptides did not have a measurable effect on the average bilayer structure, yet significantly changed the collective membrane dynamics. Despite both peptides forming transmembrane channels, they had opposite effects on the relaxation time of the collective bending fluctuations and associated effective bending modulus, where gD addition stiffened the membrane while Ala addition softened the membrane. Meanwhile, the lowest gD concentrations enhanced the collective thickness fluctuation dynamics, while the higher gD concentrations and all studied Ala concentrations dampened these dynamics. The results highlight the synergy between lipids and proteins in determining the collective membrane dynamics and that not all peptides can be universally treated as rigid bodies when considering their effects on the lipid bilayer fluctuations.
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Affiliation(s)
- Elizabeth G Kelley
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA.
| | - Paul D Butler
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA. and Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, USA and Department of Chemistry, The University of Tennessee Knoxville, TN 37996, USA
| | - Michihiro Nagao
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA. and Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742, USA and Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
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15
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Pezeshkian W, Ipsen JH. Creasing of flexible membranes at vanishing tension. Phys Rev E 2021; 103:L041001. [PMID: 34005975 DOI: 10.1103/physreve.103.l041001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 03/30/2021] [Indexed: 11/07/2022]
Abstract
The properties of freestanding tensionless interfaces and membranes at low bending rigidity κ are dominated by strong fluctuations and self-avoidance and are thus outside the range of standard perturbative analysis. We analyze this regime by a simple discretized, self-avoiding membrane model on a frame subject to periodic boundary conditions by use of Monte Carlo simulation and dynamically triangulated surface techniques. We find that at low bending rigidities, the membrane properties fall into three regimes: Below the collapse transition κ_{BP} it is subject to branched polymer instability where the framed surface is not defined, in a range below a threshold rigidity κ_{c} the conformational correlation function are characterized by power-law behavior with a continuously varying exponent α, 2<α≤4 and above κ_{c}, α=4 characteristic for linearized bending excitations. Response functions specific heat and area compressibility display pronounced peaks close to κ_{c}. The results may be important for the description of soft interface systems, such as microemulsions and membranes with in-plane cooperative phenomena.
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Affiliation(s)
- Weria Pezeshkian
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - John H Ipsen
- MEMPHYS/PhyLife, Department of Physics, Chemistry and Pharmacy (FKF), University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
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16
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Alvares DS, Monti MR, Ruggiero Neto J, Wilke N. The antimicrobial peptide Polybia-MP1 differentiates membranes with the hopanoid, diplopterol from those with cholesterol. BBA ADVANCES 2021; 1:100002. [PMID: 37082019 PMCID: PMC10074923 DOI: 10.1016/j.bbadva.2021.100002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Polybia-MP1 is an antimicrobial peptide that shows a decreased activity in membranes with cholesterol (CHO). Since it is now accepted that hopanoids act as sterol-surrogates in some sterol-lacking bacteria, we here inquire about the impact of Polybia-MP1 on membranes containing the hopanoid diplopterol (DP) in comparison to membranes with CHO. We found that, despite the properties induced on lipid membranes by DP are similar to those induced by CHO, the effect of Polybia-MP1 on membranes with CHO or DP was significantly different. DP did not prevent dye release from LUVs, nor the insertion of Polybia-MP1 into monolayers, and peptide-membrane affinity was higher for those with DP than with CHO. Zeta potentials ( ζ ) for DP-containing LUVs showed a complex behavior at increasing peptide concentration. The effect of the peptide on membrane elasticity, investigated by nanotube retraction experiments, showed that peptide addition softened all membrane compositions, but membranes with DP got stiffer at long times. Considering this, and the ζ results, we propose that peptides accumulate at the interface adopting different arrangements, leading to a non-monotonic behavior. Possible correlations with cell membranes were inquired testing the antimicrobial activity of Polybia-MP1 against hopanoid-lacking bacteria pre-incubated with DP or CHO. The fraction of surviving cells was lower in cultures incubated with DP compared to those incubated with CHO. We propose that the higher activity of Polybia-MP1 against some bacteria compared to mammalian cells is not only related to membrane electrostatics, but also the composition of neutral lipids, particularly the hopanoids, could be important.
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17
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Affiliation(s)
- Chandra Has
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India
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18
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Pinigin KV, Kuzmin PI, Akimov SA, Galimzyanov TR. Additional contributions to elastic energy of lipid membranes: Tilt-curvature coupling and curvature gradient. Phys Rev E 2020; 102:042406. [PMID: 33212684 DOI: 10.1103/physreve.102.042406] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 09/09/2020] [Indexed: 11/07/2022]
Abstract
Lipid bilayer membranes under biologically relevant conditions are flexible thin laterally fluid films consisting of two unimolecular layers (monolayers) each about 2 nm thick. On spatial scales much larger than the bilayer thickness, the membrane elasticity is well determined by its shape. The classical Helfrich theory considers the membrane as an elastic two-dimensional (2D) film, which has no particular internal structure. However, various local membrane heterogeneities can result in a lipids tilt relative to the membrane surface normal. On the basis of the classical elasticity theory of 3D bodies, Hamm and Kozlov [Eur. Phys. J. E 3, 323 (2000)10.1007/s101890070003] derived the most general energy functional, taking into account the tilt and lipid monolayer curvature. Recently, Terzi and Deserno [J. Chem. Phys. 147, 084702 (2017)10.1063/1.4990404] showed that Hamm and Kozlov's derivation was incomplete because the tilt-curvature coupling term had been missed. However, the energy functional derived by Terzi and Deserno appeared to be unstable, thereby being invalid for applications that require minimizations of the overall energy of deformations. Here, we derive a stable elastic energy functional, showing that the squared gradient of the curvature was missed in both of these works. This change in the energy functional arises from a more accurate consideration of the transverse shear deformation terms and their influence on the membrane stability. We also consider the influence of the prestress terms on the stability of the energy functional, and we show that it should be considered small and the effective Gaussian curvature should be neglected because of the stability requirements. We further generalize the theory, including the stretching-compressing deformation modes, and we provide the geometrical interpretation of the terms that were previously missed by Hamm and Kozlov. The physical consequences of the new terms are analyzed in the case of a membrane-mediated interaction of two amphipathic peptides located in the same monolayer. We also provide the expression for director fluctuations, comparing it with that obtained by Terzi and Deserno.
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Affiliation(s)
- Konstantin V Pinigin
- A. N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy prospekt, Moscow 119071, Russia
| | - Peter I Kuzmin
- A. N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy prospekt, Moscow 119071, Russia
| | - Sergey A Akimov
- A. N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy prospekt, Moscow 119071, Russia
| | - Timur R Galimzyanov
- A. N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy prospekt, Moscow 119071, Russia
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19
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Nagao M, Bradbury R, Ansar SM, Kitchens CL. Effect of gold nanoparticle incorporation into oil-swollen surfactant lamellar membranes. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2020; 7:065102. [PMID: 33344674 PMCID: PMC7744122 DOI: 10.1063/4.0000041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 11/25/2020] [Indexed: 05/08/2023]
Abstract
An oil-swollen surfactant membrane is employed to measure the effects of incorporated hydrophobically functionalized gold nanoparticles (AuNPs) on the structure and dynamics of the membranes. While maintaining an average AuNP diameter of approximately 5 nm, the membrane thickness was varied from 5 nm to 7.5 nm by changing the amount of oil in the membrane. The membranes become softer as the proportion of oil is increased, while the thickness fluctuations become slower. We attribute this to an increased fluctuation wavelength. Incorporation of AuNPs in the membrane induces membrane thinning and softening. Oil molecules surround the nanoparticles in the membrane and help their relatively homogeneous distribution. AuNPs significantly alter the membrane's structure and dynamics through thinning of the membrane, increased compressibility, and possible diffusion of AuNPs inside the membrane.
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Affiliation(s)
| | | | - Siyam M. Ansar
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, South Carolina 29634, USA
| | - Christopher L. Kitchens
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, South Carolina 29634, USA
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20
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Paternò GM, Bondelli G, Sakai VG, Sesti V, Bertarelli C, Lanzani G. The Effect of an Intramembrane Light-Actuator on the Dynamics of Phospholipids in Model Membranes and Intact Cells. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:11517-11527. [PMID: 32903010 DOI: 10.1021/acs.langmuir.0c01846] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The noncovalent intercalation of amphiphilic molecules in the lipid membrane can be exploited to modulate efficiently the physical status of the membrane. Such effects are largely employed in a range of applications, spanning from drug-delivery to therapeutics. In this context, we have very recently developed an intramembrane photo-actuator consisting of an amphiphilic azobenzene molecule, namely ZIAPIN2. The selective photo-isomerization occurring in the lipid bilayer induces a photo-triggered change in the membrane thickness and capacitance, eventually permitting to evoke light-induced neuronal firing both in vitro and in vivo. Here, we present a study on the dynamical perturbation in the lipid membrane caused by ZIAPIN2 and its vehicle solvent, dimethyl sulfoxide. Effects on the dynamics occurring in the picosecond time range and at the molecular level are probed using quasi-elastic neutron scattering. By coupling experiments carried out both on model membranes and intact cells, we found that DMSO leads to a general retardation of the dynamics within a more dynamically ordered landscape, a result that we attribute to the dehydration at the interface. On the other hand, ZIAPIN2 partitioning produces a general softening of the bilayer owing to its interaction with the lipids. These data are in agreement with our recent studies, which indicate that the efficacy of ZIAPIN2 in triggering cellular signalling stems from its ability to mechanically perturb the bilayer as a whole, by forming light-sensitive membrane spanning dimers.
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Affiliation(s)
- Giuseppe M Paternò
- Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Pascoli 10, 20133 Milano, Italy
| | - Gaia Bondelli
- Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Pascoli 10, 20133 Milano, Italy
| | - Victoria Garcia Sakai
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX, U.K
| | - Valentina Sesti
- Dipartimento di Chimica, Materiali e Ingegneria Chimica ″Giulio Natta″, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano, Italy
| | - Chiara Bertarelli
- Dipartimento di Chimica, Materiali e Ingegneria Chimica ″Giulio Natta″, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano, Italy
| | - Guglielmo Lanzani
- Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Pascoli 10, 20133 Milano, Italy
- Dipartimento di Fisica, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano, Italy
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21
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Goršak T, Drab M, Križaj D, Jeran M, Genova J, Kralj S, Lisjak D, Kralj-Iglič V, Iglič A, Makovec D. Magneto-mechanical actuation of barium-hexaferrite nanoplatelets for the disruption of phospholipid membranes. J Colloid Interface Sci 2020; 579:508-519. [PMID: 32623117 DOI: 10.1016/j.jcis.2020.06.079] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/01/2020] [Accepted: 06/18/2020] [Indexed: 01/09/2023]
Abstract
HYPOTHESIS The magneto-mechanical actuation (MMA) of magnetic nanoparticles with a low-frequency alternating magnetic field (AMF) can be used to destroy cancer cells. So far, MMA was tested on different cells using different nanoparticles and different field characteristics, which makes comparisons and any generalizations about the results of MMA difficult. In this paper we propose the use of giant unilamellar vesicles (GUVs) as a simple model system to study the effect of MMA on a closed lipid bilayer membrane, i.e., a basic building block of any cell. EXPERIMENTS The GUVs were exposed to barium-hexaferrite nanoplatelets (NPLs, ~50 nm wide and 3 nm thick) with unique magnetic properties dominated by a permanent magnetic moment that is perpendicular to the platelet, at different concentrations (1-50 µg/mL) and pH values (4.2-7.4) of the aqueous suspension. The GUVs were observed with an optical microscope while being exposed to a uniaxial AMF (3-100 Hz, 2.2-10.6 mT). FINDINGS When the NPLs were electrostatically attached to the GUV membranes, the MMA induced cyclic fluctuations of the GUVs' shape corresponding to the AMF frequency at the low NPL concentration (1 µm/mL), whereas the GUVs were bursting at the higher concentration (10 µg/mL). Theoretical considerations suggested that the bursting of the GUVs is a consequence of the local action of an assembly of several NPLs, rather than a collective effect of all the absorbed NPLs.
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Affiliation(s)
- Tanja Goršak
- Department for Materials Synthesis, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Mitja Drab
- Laboratory of Physics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, SI-1000 Ljubljana, Slovenia
| | - Dejan Križaj
- Laboratory of Bioelectromagnetics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, SI-1000 Ljubljana, Slovenia
| | - Marko Jeran
- Laboratory of Physics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, SI-1000 Ljubljana, Slovenia; Laboratory of Clinical Biophysics, Faculty of Health Sciences, University of Ljubljana, Zdravstvena pot 5, SI-1000 Ljubljana, Slovenia
| | - Julia Genova
- Institute of Solid State Physics, Bulgarian Academy of Sciences, Tzarigradsko 72, 784 Sofia, Bulgaria
| | - Slavko Kralj
- Department for Materials Synthesis, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Darja Lisjak
- Department for Materials Synthesis, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Veronika Kralj-Iglič
- Laboratory of Clinical Biophysics, Faculty of Health Sciences, University of Ljubljana, Zdravstvena pot 5, SI-1000 Ljubljana, Slovenia
| | - Aleš Iglič
- Laboratory of Physics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, SI-1000 Ljubljana, Slovenia
| | - Darko Makovec
- Department for Materials Synthesis, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
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22
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Rodriguez-Quijada C, Dahl JB. Non-contact microfluidic mechanical property measurements of single apoptotic bodies. Biochim Biophys Acta Gen Subj 2020; 1865:129657. [PMID: 32512171 DOI: 10.1016/j.bbagen.2020.129657] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 03/18/2020] [Accepted: 06/02/2020] [Indexed: 01/29/2023]
Abstract
BACKGROUND Cells exchange information by secreting micro- and nanosized extracellular vesicles (EVs), ranging from exosomes (30-100 nm) to apoptotic bodies (ABs, 1-5 μm). There is still much to understand about fundamental EV biological, physical, and chemical properties before clinical applications can be developed. EV mechanical properties have only been measured with atomic force microscopy (AFM) with its problematic adhesion and hard substrate effects. To understand EV mechanical behavior in less extreme mechanical conditions relevant to blood flow and many soft tissue environments, a non-contact measurement technique is needed. METHODS We measured the mechanical properties of single microscale ABs derived from human blood plasma using non-contact microfluidics. EVs were gently stretched in extensional flow, similar to a traditional tensile test, and a linear mechanical model was applied to estimate mechanical stiffnesses from the observed stretching. RESULTS The effective shear elastic modulus of ABs in non-contact flow conditions is approximately 5.6 ± 0.5 Pa, 7 orders of magnitude lower than previously reported AFM-measured biological exosome stiffnesses and 200 times smaller than suspended cells. CONCLUSIONS Apoptotic bodies are very soft in fluid environments and exhibit lower effective stiffnesses than suspended cells. By measuring ABs in a natural fluid environment and low-force regime without hard probes and surfaces, we achieved closer agreement with linear mechanical theory and therefore more accurate stiffness measurements. GENERAL SIGNIFICANCE AFM manufacturers and users should consider implementing new mechanical models to interpret AFM force indentation curves so that accurate extracellular vesicle mechanical properties can be extracted.
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Affiliation(s)
| | - Joanna B Dahl
- Engineering Department, University of Massachusetts Boston, Boston, MA 02125, United States of America.
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23
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Pezeshkian W, Ipsen JH. Fluctuations and conformational stability of a membrane patch with curvature inducing inclusions. SOFT MATTER 2019; 15:9974-9981. [PMID: 31754667 DOI: 10.1039/c9sm01762c] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Membranes with curvature inducing inclusions display a range of cooperative phenomena, which can be linked to biomembrane function, e.g. membrane tubulation, vesiculation, softening and spontaneous tension. We investigate how these phenomena are related for a fluctuating, framed membrane through analysis of a descretized membrane model by Monte Carlo simulation techniques. The membrane model is based on a dynamically triangulated surface equipped with non-interacting, up-down symmetry breaking inclusions where only terms coupled linearly to mean-curvature are maintained. We show that the lateral configurational entropy plays a key role for the mechanical properties of the semi-flexible membrane, e.g. a pronounced softening at intermediate inclusion coverages of the membrane and generation of membrane tension. Tensionless framed membranes will remain quasi-flat up to some threshold coverage, where a shape instability occurs with formation of pearling or tubular membranes, which below full coverage is associated with segregation of inclusions between the curved and flat membrane geometries. For inclusions with preference for highly curved membranes the instability appears at dilute inclusion coverages and is accompanied by strong configurational fluctuations.
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Affiliation(s)
- Weria Pezeshkian
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands.
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Interaction of a Polyarginine Peptide with Membranes of Different Mechanical Properties. Biomolecules 2019; 9:biom9100625. [PMID: 31635304 PMCID: PMC6843195 DOI: 10.3390/biom9100625] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 10/15/2019] [Accepted: 10/17/2019] [Indexed: 01/18/2023] Open
Abstract
The membrane translocation efficiency of cell penetrating peptides (CPPs) has been largely studied, and poly-arginines have been highlighted as particularly active CPPs, especially upon negatively charged membranes. Here we inquire about the influence of membrane mechanical properties in poly-arginine adsorption, penetration and translocation, as well as the subsequent effect on the host membrane. For this, we selected anionic membranes exhibiting different rigidity and fluidity, and exposed them to the nona-arginine KR9C. Three different membrane compositions were investigated, all of them having 50% of the anionic lipid 1,2-dioleoyl-sn-glycero-3-phospho-(1’-rac-glycerol) (DOPG), thus, ensuring a high affinity of the peptide for membrane surfaces. The remaining 50% was a saturated PC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DPPC), an unsaturated PC (1,2-dioleoyl-sn-glycero-3-phosphocholine, DOPC) or a mixture of DOPC with cholesterol. Peptide-membrane interactions were studied using four complementary models for membranes: Langmuir monolayers, Large Unilamellar Vesicles, Black Lipid Membranes and Giant Unilamellar Vesicles. The patterns of interaction of KR9C varied within the different membrane compositions. The peptide strongly adsorbed on membranes with cholesterol, but did not incorporate or translocate them. KR9C stabilized phase segregation in DPPC/DOPG films and promoted vesicle rupture. DOPC/DOPG appeared like the better host for peptide translocation: KR9C adsorbed, inserted and translocated these membranes without breaking them, despite softening was observed.
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25
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Mescola A, Marín-Medina N, Ragazzini G, Accolla M, Alessandrini A. Magainin-H2 effects on the permeabilization and mechanical properties of giant unilamellar vesicles. J Colloid Interface Sci 2019; 553:247-258. [PMID: 31207545 DOI: 10.1016/j.jcis.2019.06.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 05/28/2019] [Accepted: 06/09/2019] [Indexed: 10/26/2022]
Abstract
Among the potential novel therapeutics to treat bacterial infections, antimicrobial peptides (AMPs) are a very promising substitute due to their broad-spectrum activity and rapid bactericidal action. AMPs strongly interact with the bacterial membrane, and the need to have a correct understanding of the interaction between AMPs and lipid bilayers at a molecular level prompted a wealth of experimental and theoretical studies exploiting a variety of AMPs. Here, we studied the effects of magainin H2 (Mag H2), an analog of the well-known magainin 2 (wt Mag 2) AMP endowed with a higher degree of hydrophobicity, on giant unilamellar vesicles (GUVs) concentrating on its permeabilization activity and the effect on the lipid bilayer mechanical properties. We demonstrated that the increased hydrophobicity of Mag H2 affects its selectivity conferring a strong permeabilization activity also on zwitterionic lipid bilayers. Moreover, when lipid mixtures including PG lipids are considered, PG has a protective effect, at variance from wt Mag 2, suggesting that for Mag H2 the monolayer curvature could prevail over the peptide-membrane electrostatic interaction. We then mechanically characterized GUVs by measuring the effect of Mag H2 on the bending constant of lipid bilayers by flickering spectroscopy and, by using micropipette aspiration technique, we followed the steps leading to vesicle permeabilization. We found that Mag H2, notwithstanding its enhanced hydrophobicity, has a pore formation mechanism compatible with the toroidal pore model similar to that of wt Mag 2.
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Affiliation(s)
- Andrea Mescola
- CNR-Nanoscience Institute-S3, Via Campi 213/A, 41125 Modena, Italy.
| | - Nathaly Marín-Medina
- Department of Physics, University of Los Andes, Carrera 1 N° 18A - 12, Bogotá, Colombia.
| | - Gregorio Ragazzini
- CNR-Nanoscience Institute-S3, Via Campi 213/A, 41125 Modena, Italy; Department of Physics, Informatics and Mathematics, University of Modena and Reggio Emilia, Via Campi 213/A, 41125 Modena, Italy.
| | - Maurizio Accolla
- Department of Physics, Informatics and Mathematics, University of Modena and Reggio Emilia, Via Campi 213/A, 41125 Modena, Italy
| | - Andrea Alessandrini
- CNR-Nanoscience Institute-S3, Via Campi 213/A, 41125 Modena, Italy; Department of Physics, Informatics and Mathematics, University of Modena and Reggio Emilia, Via Campi 213/A, 41125 Modena, Italy.
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26
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Kelley EG, Butler PD, Nagao M. Scaling of lipid membrane rigidity with domain area fraction. SOFT MATTER 2019; 15:2762-2767. [PMID: 30789180 PMCID: PMC8220873 DOI: 10.1039/c8sm02362j] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Biological membranes are highly heterogeneous in composition which in turn leads to local variations in the physical properties. Here we quantify how heterogeneity in stiffness determines the effective bending modulus, κeff, of model phase-separated membranes with coexisting soft fluid and rigid gel domains. We find that the temperature- and composition- dependent trends in membrane rigidity collapse onto a single curve, such that κeff directly scales with the area fraction of the rigid gel domains. Using no adjustable parameters, the measurements are found to agree with theoretical predictions for inhomogenous membranes and indicate that κeff is sensitive to the lateral distribution of the rigid phase within the membrane. This key finding confirms that the properties of heterogeneous membranes can be quantitatively predicted if the area fraction and properties of the individual phases are known.
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Affiliation(s)
- Elizabeth G Kelley
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD, USA.
| | - Paul D Butler
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD, USA. and Department of Chemical and Biomolecular Engineering, University of Delaware, 150 Academy Street, Newark, DE, USA and Department of Chemistry, The University of Tennessee, Knoxville, TN 37996, USA
| | - Michihiro Nagao
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD, USA. and Center for Exploration of Energy and Matter, Indiana University, 2401 N. Milo B. Sampson Lane, Bloomington, IN, USA.
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27
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Effects of the peptide Magainin H2 on Supported Lipid Bilayers studied by different biophysical techniques. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:2635-2643. [DOI: 10.1016/j.bbamem.2018.10.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 10/02/2018] [Indexed: 11/24/2022]
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28
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Methods of reconstitution to investigate membrane protein function. Methods 2018; 147:126-141. [DOI: 10.1016/j.ymeth.2018.02.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 02/13/2018] [Indexed: 02/06/2023] Open
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29
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Boye TL, Jeppesen JC, Maeda K, Pezeshkian W, Solovyeva V, Nylandsted J, Simonsen AC. Annexins induce curvature on free-edge membranes displaying distinct morphologies. Sci Rep 2018; 8:10309. [PMID: 29985397 PMCID: PMC6037701 DOI: 10.1038/s41598-018-28481-z] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 06/19/2018] [Indexed: 12/31/2022] Open
Abstract
Annexins are a family of proteins characterized by their ability to bind anionic membranes in response to Ca2+-activation. They are involved in a multitude of cellular functions including vesiculation and membrane repair. Here, we investigate the effect of nine annexins (ANXA1-ANXA7, ANXA11, ANXA13) on negatively charged double supported membrane patches with free edges. We find that annexin members can be classified according to the membrane morphology they induce and matching a dendrogam of the annexin family based on full amino acid sequences. ANXA1 and ANXA2 induce membrane folding and blebbing initiated from membrane structural defects inside patches while ANXA6 induces membrane folding originating both from defects and from the membrane edges. ANXA4 and ANXA5 induce cooperative roll-up of the membrane starting from free edges, producing large rolls. In contrast, ANXA3 and ANXA13 roll the membrane in a fragmented manner producing multiple thin rolls. In addition to rolling, ANXA7 and ANXA11 are characterized by their ability to form fluid lenses localized between the membrane leaflets. A shared feature necessary for generating these morphologies is the ability to induce membrane curvature on free edged anionic membranes. Consequently, induction of membrane curvature may be a significant property of the annexin protein family that is important for their function.
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Affiliation(s)
- Theresa Louise Boye
- Membrane Integrity Group, Unit for Cell Death and Metabolism, Danish Cancer Society Research Center, Strandboulevarden 49, DK-2100, Copenhagen, Denmark
| | - Jonas Camillus Jeppesen
- University of Southern Denmark (SDU), Campusvej 55, DK-5230, Odense M, Denmark.,Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark
| | - Kenji Maeda
- Membrane Integrity Group, Unit for Cell Death and Metabolism, Danish Cancer Society Research Center, Strandboulevarden 49, DK-2100, Copenhagen, Denmark
| | - Weria Pezeshkian
- University of Southern Denmark (SDU), Campusvej 55, DK-5230, Odense M, Denmark.,Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark
| | - Vita Solovyeva
- University of Southern Denmark (SDU), Campusvej 55, DK-5230, Odense M, Denmark.,Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Jesper Nylandsted
- Membrane Integrity Group, Unit for Cell Death and Metabolism, Danish Cancer Society Research Center, Strandboulevarden 49, DK-2100, Copenhagen, Denmark.,Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, DK-2200, Copenhagen N, Denmark
| | - Adam Cohen Simonsen
- University of Southern Denmark (SDU), Campusvej 55, DK-5230, Odense M, Denmark. .,Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark.
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30
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Effects of electroformation protocol parameters on quality of homogeneous GUV populations. Chem Phys Lipids 2018; 212:88-95. [DOI: 10.1016/j.chemphyslip.2018.01.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 12/28/2017] [Accepted: 01/08/2018] [Indexed: 12/22/2022]
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31
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Grasso G, Muscat S, Rebella M, Morbiducci U, Audenino A, Danani A, Deriu MA. Cell penetrating peptide modulation of membrane biomechanics by Molecular dynamics. J Biomech 2018; 73:137-144. [PMID: 29631749 DOI: 10.1016/j.jbiomech.2018.03.036] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 03/14/2018] [Accepted: 03/21/2018] [Indexed: 11/17/2022]
Abstract
The efficacy of a pharmaceutical treatment is often countered by the inadequate membrane permeability, that prevents drugs from reaching their specific intracellular targets. Cell penetrating peptides (CPPs) are able to route across cells' membrane various types of cargo, including drugs and nanoparticles. However, CPPs internalization mechanisms are not yet fully understood and depend on a wide variety of aspects. In this contest, the entry of a CPP into the lipid bilayer might induce molecular conformational changes, including marked variations on membrane's mechanical properties. Understanding how the CPP does influence the mechanical properties of cells membrane is crucial to design, engineer and improve new and existing penetrating peptides. Here, all atom Molecular Dynamics (MD) simulations were used to investigate the interaction between different types of CPPs embedded in a lipid bilayer of dioleoyl phosphatidylcholine (DOPC). In a greater detail, we systematically highlighted how CPP properties are responsible for modulating the membrane bending modulus. Our findings highlighted the CPP hydropathy strongly correlated with penetration of water molecules in the lipid bilayer, thus supporting the hypothesis that the amount of water each CPP can route inside the membrane is modulated by the hydrophobic and hydrophilic character of the peptide. Water penetration promoted by CPPs leads to a local decrease of the lipid order, which emerges macroscopically as a reduction of the membrane bending modulus.
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Affiliation(s)
- Gianvito Grasso
- Istituto Dalle Molle di Studi sull'Intelligenza Artificiale (IDSIA), Scuola universitaria professionale della Svizzera italiana (SUPSI), Università della Svizzera Italiana (USI), Centro Galleria 2, Manno CH-6928, Switzerland
| | - Stefano Muscat
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, IT-10128 Torino, Italy
| | - Martina Rebella
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, IT-10128 Torino, Italy
| | - Umberto Morbiducci
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, IT-10128 Torino, Italy
| | - Alberto Audenino
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, IT-10128 Torino, Italy
| | - Andrea Danani
- Istituto Dalle Molle di Studi sull'Intelligenza Artificiale (IDSIA), Scuola universitaria professionale della Svizzera italiana (SUPSI), Università della Svizzera Italiana (USI), Centro Galleria 2, Manno CH-6928, Switzerland
| | - Marco A Deriu
- Istituto Dalle Molle di Studi sull'Intelligenza Artificiale (IDSIA), Scuola universitaria professionale della Svizzera italiana (SUPSI), Università della Svizzera Italiana (USI), Centro Galleria 2, Manno CH-6928, Switzerland.
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32
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Palmitoylation Contributes to Membrane Curvature in Influenza A Virus Assembly and Hemagglutinin-Mediated Membrane Fusion. J Virol 2017; 91:JVI.00947-17. [PMID: 28794042 DOI: 10.1128/jvi.00947-17] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 07/27/2017] [Indexed: 12/31/2022] Open
Abstract
The highly conserved cytoplasmic tail of influenza virus glycoprotein hemagglutinin (HA) contains three cysteines, posttranslationally modified by covalently bound fatty acids. While viral HA acylation is crucial in virus replication, its physico-chemical role is unknown. We used virus-like particles (VLP) to study the effect of acylation on morphology, protein incorporation, lipid composition, and membrane fusion. Deacylation interrupted HA-M1 interactions since deacylated mutant HA failed to incorporate an M1 layer within spheroidal VLP, and filamentous particles incorporated increased numbers of neuraminidase (NA). While HA acylation did not influence VLP shape, lipid composition, or HA lateral spacing, acylation significantly affected envelope curvature. Compared to wild-type HA, deacylated HA is correlated with released particles with flat envelope curvature in the absence of the matrix (M1) protein layer. The spontaneous curvature of palmitate was calculated by molecular dynamic simulations and was found to be comparable to the curvature values derived from VLP size distributions. Cell-cell fusion assays show a strain-independent failure of fusion pore enlargement among H2 (A/Japan/305/57), H3 (A/Aichi/2/68), and H3 (A/Udorn/72) viruses. In contradistinction, acylation made no difference in the low-pH-dependent fusion of isolated VLPs to liposomes: fusion pores formed and expanded, as demonstrated by the presence of complete fusion products observed using cryo-electron tomography (cryo-ET). We propose that the primary mechanism of action of acylation is to control membrane curvature and to modify HA's interaction with M1 protein, while the stunting of fusion by deacylated HA acting in isolation may be balanced by other viral proteins which help lower the energetic barrier to pore expansion.IMPORTANCE Influenza A virus is an airborne pathogen causing seasonal epidemics and occasional pandemics. Hemagglutinin (HA), a glycoprotein abundant on the virion surface, is important in both influenza A virus assembly and entry. HA is modified by acylation whose removal abrogates viral replication. Here, we used cryo-electron tomography to obtain three-dimensional images to elucidate a role for HA acylation in VLP assembly. Our data indicate that HA acylation contributes to the capability of HA to bend membranes and to HA's interaction with the M1 scaffold protein during virus assembly. Furthermore, our data on VLP and, by hypothesis, virus suggests that HA acylation, while not critical to fusion pore formation, contributes to pore expansion in a target-dependent fashion.
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33
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Pan J, Sahoo PK, Dalzini A, Hayati Z, Aryal CM, Teng P, Cai J, Gutierrez HR, Song L. Membrane Disruption Mechanism of a Prion Peptide (106-126) Investigated by Atomic Force Microscopy, Raman and Electron Paramagnetic Resonance Spectroscopy. J Phys Chem B 2017; 121:5058-5071. [PMID: 28459565 PMCID: PMC5770145 DOI: 10.1021/acs.jpcb.7b02772] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A fragment of the human prion protein spanning residues 106-126 (PrP106-126) recapitulates many essential properties of the disease-causing protein such as amyloidogenicity and cytotoxicity. PrP106-126 has an amphipathic characteristic that resembles many antimicrobial peptides (AMPs). Therefore, the toxic effect of PrP106-126 could arise from a direct association of monomeric peptides with the membrane matrix. Several experimental approaches are employed to scrutinize the impacts of monomeric PrP106-126 on model lipid membranes. Porous defects in planar bilayers are observed by using solution atomic force microscopy. Adding cholesterol does not impede defect formation. A force spectroscopy experiment shows that PrP106-126 reduces Young's modulus of planar lipid bilayers. We use Raman microspectroscopy to study the effect of PrP106-126 on lipid atomic vibrational dynamics. For phosphatidylcholine lipids, PrP106-126 disorders the intrachain conformation, while the interchain interaction is not altered; for phosphatidylethanolamine lipids, PrP106-126 increases the interchain interaction, while the intrachain conformational order remains similar. We explain the observed differences by considering different modes of peptide insertion. Finally, electron paramagnetic resonance spectroscopy shows that PrP106-126 progressively decreases the orientational order of lipid acyl chains in magnetically aligned bicelles. Together, our experimental data support the proposition that monomeric PrP106-126 can disrupt lipid membranes by using similar mechanisms found in AMPs.
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Affiliation(s)
- Jianjun Pan
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
| | - Prasana K. Sahoo
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
| | - Annalisa Dalzini
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Zahra Hayati
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Chinta M. Aryal
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
| | - Peng Teng
- Department of Chemistry, University of South Florida, Tampa, Florida 33620, United States
| | - Jianfeng Cai
- Department of Chemistry, University of South Florida, Tampa, Florida 33620, United States
| | | | - Likai Song
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
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34
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Khadka NK, Teng P, Cai J, Pan J. Modulation of lipid membrane structural and mechanical properties by a peptidomimetic derived from reduced amide scaffold. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:734-744. [PMID: 28132901 DOI: 10.1016/j.bbamem.2017.01.026] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 01/22/2017] [Accepted: 01/25/2017] [Indexed: 10/20/2022]
Abstract
Understanding how antimicrobial peptidomimetics interact with lipid membranes is important in battling multidrug resistant bacterial pathogens. We study the effects of a recently reported peptidomimetic on lipid bilayer structural and mechanical properties. The compound referred to as E107-3 is synthesized based on the acylated reduced amide scaffold and has been shown to exhibit good antimicrobial potency. Our vesicle leakage assay indicates that the compound increases lipid bilayer permeability. We use micropipette aspiration to explore the kinetic response of giant unilamellar vesicles (GUVs). Exposure to the compound causes the GUV protrusion length LP to spontaneously increase and then decrease, followed by GUV rupture. Solution atomic force microscopy (AFM) is used to visualize lipid bilayer structural modulation within a nanoscopic regime. Unlike melittin, which produces pore-like structures, the peptidomimetic compound is found to induce nanoscopic heterogeneous structures. Finally, we use AFM-based force spectroscopy to study the impact of the compound on lipid bilayer mechanical properties. We find that incremental addition of the compound to planar lipid bilayers results in a moderate decrease of the bilayer puncture force FP and a 39% decrease of the bilayer area compressibility modulus KA. To explain our experimental data, we propose a membrane interaction model encompassing disruption of lipid chain packing and extraction of lipid molecules. The later action mode is supported by our observation of a double-bilayer structure in the presence of fusogenic calcium ions.
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Affiliation(s)
- Nawal K Khadka
- Department of Physics, University of South Florida, Tampa, FL 33620, United States
| | - Peng Teng
- Department of Chemistry, University of South Florida, Tampa, FL 33620, United States
| | - Jianfeng Cai
- Department of Chemistry, University of South Florida, Tampa, FL 33620, United States
| | - Jianjun Pan
- Department of Physics, University of South Florida, Tampa, FL 33620, United States.
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35
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Agrawal H, Liu L, Sharma P. Revisiting the curvature-mediated interactions between proteins in biological membranes. SOFT MATTER 2016; 12:8907-8918. [PMID: 27725970 DOI: 10.1039/c6sm01572g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Proteins embedded in soft biological membranes experience a long-range force mediated by elastic curvature deformations. The classical linearized Helfrich-Canham Hamiltonian based derivations reveal the nature of the force between a pair of proteins to be repulsive in the zero-temperature limit and the interaction potential is inversely proportional to the fourth power of the distance separating the inclusions. Such a result is the starting point to understand many-body interactions between proteins in biological membranes and the study of their clustering or, more broadly, self-organization. A key observation regarding this widely quoted result is that any two (mechanically rigid) proteins will experience an identical force. In other words, there is no specificity in the currently employed continuum models that purport to explain protein interactions. In this work we argue that each protein has a unique mechanical signature based on its interaction with the surrounding lipid bilayer membrane and cannot be treated as a non-specific rigid object. We modify the classical Helfrich-Canham theory of curvature elasticity to incorporate protein-membrane specificity, discuss the estimation of the new model parameters via atomistic simulations and re-evaluate the curvature-mediated force between proteins. We find that the incorporation of protein-specificity can reduce the interaction force by several orders of magnitude. Our result may provide at least one plausible reason behind why in some computational and experimental studies, a net attractive force between proteins is in evidence.
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Affiliation(s)
- Himani Agrawal
- Department of Mechanical Engineering, University of Houston, TX, USA
| | - Liping Liu
- Department of Mathematics and Department of Mechanical Aerospace Engineering, Rutgers University, NJ, USA.
| | - Pradeep Sharma
- Department of Mechanical Engineering and Department of Physics, University of Houston, TX, USA.
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36
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Hanson JM, Gettel DL, Tabaei SR, Jackman J, Kim MC, Sasaki DY, Groves JT, Liedberg B, Cho NJ, Parikh AN. Cholesterol-Enriched Domain Formation Induced by Viral-Encoded, Membrane-Active Amphipathic Peptide. Biophys J 2016; 110:176-87. [PMID: 26745420 DOI: 10.1016/j.bpj.2015.11.032] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 10/23/2015] [Accepted: 11/17/2015] [Indexed: 12/15/2022] Open
Abstract
The α-helical (AH) domain of the hepatitis C virus nonstructural protein NS5A, anchored at the cytoplasmic leaflet of the endoplasmic reticulum, plays a role in viral replication. However, the peptides derived from this domain also exhibit remarkably broad-spectrum virocidal activity, raising questions about their modes of membrane association. Here, using giant lipid vesicles, we show that the AH peptide discriminates between membrane compositions. In cholesterol-containing membranes, peptide binding induces microdomain formation. By contrast, cholesterol-depleted membranes undergo global softening at elevated peptide concentrations. Furthermore, in mixed populations, the presence of ∼100 nm vesicles of viral dimensions suppresses these peptide-induced perturbations in giant unilamellar vesicles, suggesting size-dependent membrane association. These synergistic composition- and size-dependent interactions explain, in part, how the AH domain might on the one hand segregate molecules needed for viral assembly and on the other hand furnish peptides that exhibit broad-spectrum virocidal activity.
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Affiliation(s)
- Joshua M Hanson
- Biophysics Graduate Group, University of California, Davis, Davis, California
| | - Douglas L Gettel
- Department of Chemical Engineering & Materials Science, University of California, Davis, Davis, California
| | - Seyed R Tabaei
- Centre for Biomimetic Sensor Science, Nanyang Technological University, Singapore; School of Materials Science and Engineering, Nanyang Technological University, Singapore
| | - Joshua Jackman
- Centre for Biomimetic Sensor Science, Nanyang Technological University, Singapore; School of Materials Science and Engineering, Nanyang Technological University, Singapore
| | - Min Chul Kim
- Centre for Biomimetic Sensor Science, Nanyang Technological University, Singapore; School of Materials Science and Engineering, Nanyang Technological University, Singapore
| | - Darryl Y Sasaki
- Biotechnology and Bioengineering Department, Sandia National Laboratories, Livermore, California
| | - Jay T Groves
- Chemistry Department, University of California, Berkeley, California; Mechanobiology Institute, National University of Singapore, Singapore
| | - Bo Liedberg
- Centre for Biomimetic Sensor Science, Nanyang Technological University, Singapore; School of Materials Science and Engineering, Nanyang Technological University, Singapore
| | - Nam-Joon Cho
- Centre for Biomimetic Sensor Science, Nanyang Technological University, Singapore; School of Materials Science and Engineering, Nanyang Technological University, Singapore; School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore
| | - Atul N Parikh
- Biophysics Graduate Group, University of California, Davis, Davis, California; Department of Chemical Engineering & Materials Science, University of California, Davis, Davis, California; Centre for Biomimetic Sensor Science, Nanyang Technological University, Singapore; School of Materials Science and Engineering, Nanyang Technological University, Singapore; Department of Biomedical Engineering, University of California, Davis, Davis, California.
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37
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Fowler PW, Hélie J, Duncan A, Chavent M, Koldsø H, Sansom MSP. Membrane stiffness is modified by integral membrane proteins. SOFT MATTER 2016; 12:7792-7803. [PMID: 27722554 PMCID: PMC5314686 DOI: 10.1039/c6sm01186a] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 08/25/2016] [Indexed: 05/12/2023]
Abstract
The ease with which a cell membrane can bend and deform is important for a wide range of biological functions. Peripheral proteins that induce curvature in membranes (e.g. BAR domains) have been studied for a number of years. Little is known, however, about the effect of integral membrane proteins on the stiffness of a membrane (characterised by the bending rigidity, Kc). We demonstrate by computer simulation that adding integral membrane proteins at physiological densities alters the stiffness of the membrane. First we establish that the coarse-grained MARTINI forcefield is able to accurately reproduce the bending rigidity of a small patch of 1500 phosphatidyl choline lipids by comparing the calculated value to both experiment and an atomistic simulation of the same system. This enables us to simulate the dynamics of large (ca. 50 000 lipids) patches of membrane using the MARTINI coarse-grained description. We find that altering the lipid composition changes the bending rigidity. Adding integral membrane proteins to lipid bilayers also changes the bending rigidity, whilst adding a simple peripheral membrane protein has no effect. Our results suggest that integral membrane proteins can have different effects, and in the case of the bacterial outer membrane protein, BtuB, the greater the density of protein, the larger the reduction in stiffness.
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Affiliation(s)
- Philip W Fowler
- Department of Biochemistry, University of Oxford, South Parks Rd, Oxford, OX1 3QU, UK.
| | - Jean Hélie
- Department of Biochemistry, University of Oxford, South Parks Rd, Oxford, OX1 3QU, UK.
| | - Anna Duncan
- Department of Biochemistry, University of Oxford, South Parks Rd, Oxford, OX1 3QU, UK.
| | - Matthieu Chavent
- Department of Biochemistry, University of Oxford, South Parks Rd, Oxford, OX1 3QU, UK.
| | - Heidi Koldsø
- Department of Biochemistry, University of Oxford, South Parks Rd, Oxford, OX1 3QU, UK.
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, South Parks Rd, Oxford, OX1 3QU, UK.
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38
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Gleisner M, Kroppen B, Fricke C, Teske N, Kliesch TT, Janshoff A, Meinecke M, Steinem C. Epsin N-terminal Homology Domain (ENTH) Activity as a Function of Membrane Tension. J Biol Chem 2016; 291:19953-61. [PMID: 27466364 DOI: 10.1074/jbc.m116.731612] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Indexed: 12/18/2022] Open
Abstract
The epsin N-terminal homology domain (ENTH) is a major player in clathrin-mediated endocytosis. To investigate the influence of initial membrane tension on ENTH binding and activity, we established a bilayer system based on adhered giant unilamellar vesicles (GUVs) to be able to control and adjust the membrane tension σ covering a broad regime. The shape of each individual adhered GUV as well as its adhesion area was monitored by spinning disc confocal laser microscopy. Control of σ in a range of 0.08-1.02 mN/m was achieved by altering the Mg(2+) concentration in solution, which changes the surface adhesion energy per unit area of the GUVs. Specific binding of ENTH to phosphatidylinositol 4,5-bisphosphate leads to a substantial increase in adhesion area of the sessile GUV. At low tension (<0.1 mN/m) binding of ENTH can induce tubular structures, whereas at higher membrane tension the ENTH interaction deflates the sessile GUV and thereby increases the adhesion area. The increase in adhesion area is mainly attributed to a decrease in the area compressibility modulus KA We propose that the insertion of the ENTH helix-0 into the membrane is largely responsible for the observed decrease in KA, which is supported by the observation that the mutant ENTH L6E shows a reduced increase in adhesion area. These results demonstrate that even in the absence of tubule formation, the area compressibility modulus and, as such, the bending rigidity of the membrane is considerably reduced upon ENTH binding. This renders membrane bending and tubule formation energetically less costly.
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Affiliation(s)
- Martin Gleisner
- From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany
| | - Benjamin Kroppen
- Department of Cellular Biochemistry, University of Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Christian Fricke
- From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany
| | - Nelli Teske
- From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany
| | - Torben-Tobias Kliesch
- Institute of Physical Chemistry, University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany, and
| | - Andreas Janshoff
- Institute of Physical Chemistry, University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany, and Göttingen Center for Molecular Biosciences, 37077 Göttingen, Germany
| | - Michael Meinecke
- Department of Cellular Biochemistry, University of Göttingen, Humboldtallee 23, 37073 Göttingen, Germany, European Neuroscience Institute, 37073 Göttingen, Germany,
| | - Claudia Steinem
- From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany, Göttingen Center for Molecular Biosciences, 37077 Göttingen, Germany
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39
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West A, Brummel BE, Braun AR, Rhoades E, Sachs JN. Membrane remodeling and mechanics: Experiments and simulations of α-Synuclein. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1858:1594-609. [PMID: 26972046 PMCID: PMC5081225 DOI: 10.1016/j.bbamem.2016.03.012] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 03/05/2016] [Accepted: 03/07/2016] [Indexed: 01/24/2023]
Abstract
We review experimental and simulation approaches that have been used to determine curvature generation and remodeling of lipid bilayers by membrane-bending proteins. Particular emphasis is placed on the complementary approaches used to study α-Synuclein (αSyn), a major protein involved in Parkinson's disease (PD). Recent cellular and biophysical experiments have shown that the protein 1) deforms the native structure of mitochondrial and model membranes; and 2) inhibits vesicular fusion. Today's advanced experimental and computational technology has made it possible to quantify these protein-induced changes in membrane shape and material properties. Collectively, experiments, theory and multi-scale simulation techniques have established the key physical determinants of membrane remodeling and rigidity: protein binding energy, protein partition depth, protein density, and membrane tension. Despite the exciting and significant progress made in recent years in these areas, challenges remain in connecting biophysical insights to the cellular processes that lead to disease. This article is part of a Special Issue entitled: Membrane Proteins edited by J.C. Gumbart and Sergei Noskov.
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Affiliation(s)
- Ana West
- Department of Biomedical Engineering, University of Minnesota, 312 Church St. SE, Minneapolis, MN 55455, USA
| | - Benjamin E Brummel
- Department of Biomedical Engineering, University of Minnesota, 312 Church St. SE, Minneapolis, MN 55455, USA
| | - Anthony R Braun
- Department of Neuroscience, University of Minnesota, 321 Church St. SE, Minneapolis, MN 55455, USA
| | - Elizabeth Rhoades
- Department of Chemistry, University of Pennsylvania, 231 S 34th St., Philadelphia, PA 19104, USA
| | - Jonathan N Sachs
- Department of Biomedical Engineering, University of Minnesota, 312 Church St. SE, Minneapolis, MN 55455, USA.
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40
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Rigid proteins and softening of biological membranes-with application to HIV-induced cell membrane softening. Sci Rep 2016; 6:25412. [PMID: 27149877 PMCID: PMC4858729 DOI: 10.1038/srep25412] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 04/14/2016] [Indexed: 11/15/2022] Open
Abstract
A key step in the HIV-infection process is the fusion of the virion membrane with the target cell membrane and the concomitant transfer of the viral RNA. Experimental evidence suggests that the fusion is preceded by considerable elastic softening of the cell membranes due to the insertion of fusion peptide in the membrane. What are the mechanisms underpinning the elastic softening of the membrane upon peptide insertion? A broader question may be posed: insertion of rigid proteins in soft membranes ought to stiffen the membranes not soften them. However, experimental observations perplexingly appear to show that rigid proteins may either soften or harden membranes even though conventional wisdom only suggests stiffening. In this work, we argue that regarding proteins as merely non-specific rigid inclusions is flawed, and each protein has a unique mechanical signature dictated by its specific interfacial coupling to the surrounding membrane. Predicated on this hypothesis, we have carried out atomistic simulations to investigate peptide-membrane interactions. Together with a continuum model, we reconcile contrasting experimental data in the literature including the case of HIV-fusion peptide induced softening. We conclude that the structural rearrangements of the lipids around the inclusions cause the softening or stiffening of the biological membranes.
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Dahl JB, Narsimhan V, Gouveia B, Kumar S, Shaqfeh ESG, Muller SJ. Experimental observation of the asymmetric instability of intermediate-reduced-volume vesicles in extensional flow. SOFT MATTER 2016; 12:3787-96. [PMID: 26984509 PMCID: PMC4838492 DOI: 10.1039/c5sm03004h] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Vesicles provide an attractive model system to understand the deformation of living cells in response to mechanical forces. These simple, enclosed lipid bilayer membranes are suitable for complementary theoretical, numerical, and experimental analysis. A recent study [Narsimhan, Spann, Shaqfeh, J. Fluid Mech., 2014, 750, 144] predicted that intermediate-aspect-ratio vesicles extend asymmetrically in extensional flow. Upon infinitesimal perturbation to the vesicle shape, the vesicle stretches into an asymmetric dumbbell with a cylindrical thread separating the two ends. While the symmetric stretching of high-aspect-ratio vesicles in extensional flow has been observed and characterized [Kantsler, Segre, Steinberg, Phys. Rev. Lett., 2008, 101, 048101] as well as recapitulated in numerical simulations by Narsimhan et al., experimental observation of the asymmetric stretching has not been reported. In this work, we present results from microfluidic cross-slot experiments observing this instability, along with careful characterization of the flow field, vesicle shape, and vesicle bending modulus. The onset of this shape transition depends on two non-dimensional parameters: reduced volume (a measure of vesicle asphericity) and capillary number (ratio of viscous to bending forces). We observed that every intermediate-reduced-volume vesicle that extends forms a dumbbell shape that is indeed asymmetric. For the subset of the intermediate-reduced-volume regime we could capture experimentally, we present an experimental phase diagram for asymmetric vesicle stretching that is consistent with the predictions of Narsimhan et al.
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Affiliation(s)
- Joanna B Dahl
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720-1460, USA.
| | - Vivek Narsimhan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Bernardo Gouveia
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720-1460, USA.
| | - Sanjay Kumar
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720-1460, USA. and Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720-1762, USA
| | - Eric S G Shaqfeh
- Department of Chemical Engineering, Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA and Institute of Computational and Mathematical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Susan J Muller
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720-1460, USA.
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42
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Drabik D, Przybyło M, Chodaczek G, Iglič A, Langner M. The modified fluorescence based vesicle fluctuation spectroscopy technique for determination of lipid bilayer bending properties. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:244-52. [DOI: 10.1016/j.bbamem.2015.11.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 11/10/2015] [Accepted: 11/21/2015] [Indexed: 11/16/2022]
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43
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Preparing giant unilamellar vesicles (GUVs) of complex lipid mixtures on demand: Mixing small unilamellar vesicles of compositionally heterogeneous mixtures. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:3175-80. [DOI: 10.1016/j.bbamem.2015.09.020] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 08/16/2015] [Accepted: 09/22/2015] [Indexed: 11/18/2022]
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44
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Esmaili E, Shahlaei M. Analysis of the flexibility and stability of the structure of magainin in a bilayer, and in aqueous and nonaqueous solutions using molecular dynamics simulations. J Mol Model 2015; 21:73. [PMID: 25750019 DOI: 10.1007/s00894-015-2622-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 02/15/2015] [Indexed: 11/25/2022]
Abstract
The precise mode of the antimicrobial activity of Magainin (Mag)-an antimicrobial peptide (AMP)-is still unclear. In this study, the conformation of Mag was characterized in water, and in a methanol and lipid bilayer [palmitoyl-oleoylphosphatidylcholine (POPC)] using a molecular dynamics (MD) simulation technique. To describe the role conformation plays in Mag function, the global conformational differences within three systems were studied. Through analysis of the resulting configuration ensembles, the differences in the three systems, such as overall flexibility and average secondary structure, were studied. It is suggested that these differences may be important enough to influence interactions with lipid biomembranes, thereby influencing key properties such as penetration into cell membrane and stability.
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Affiliation(s)
- Elham Esmaili
- Department of Biochemistry, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran
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45
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Pott T, Gerbeaud C, Barbier N, Méléard P. Melittin modifies bending elasticity in an unexpected way. Chem Phys Lipids 2015; 185:99-108. [DOI: 10.1016/j.chemphyslip.2014.05.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 04/28/2014] [Accepted: 05/18/2014] [Indexed: 12/22/2022]
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46
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Zhang M, Zhao J, Zheng J. Molecular understanding of a potential functional link between antimicrobial and amyloid peptides. SOFT MATTER 2014; 10:7425-7451. [PMID: 25105988 DOI: 10.1039/c4sm00907j] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Antimicrobial and amyloid peptides do not share common sequences, typical secondary structures, or normal biological activity but both the classes of peptides exhibit membrane-disruption ability to induce cell toxicity. Different membrane-disruption mechanisms have been proposed for antimicrobial and amyloid peptides, individually, some of which are not exclusive to either peptide type, implying that certain common principles may govern the folding and functions of different cytolytic peptides and associated membrane disruption mechanisms. Particularly, some antimicrobial and amyloid peptides have been identified to have dual complementary amyloid and antimicrobial properties, suggesting a potential functional link between amyloid and antimicrobial peptides. Given that some similar structural and membrane-disruption characteristics exist between the two classes of peptides, this review summarizes major findings, recent advances, and future challenges related to antimicrobial and amyloid peptides and strives to illustrate the similarities, differences, and relationships in the sequences, structures, and membrane interaction modes between amyloid and antimicrobial peptides, with a special focus on direct interactions of the peptides with the membranes. We hope that this review will stimulate further research at the interface of antimicrobial and amyloid peptides - which has been studied less intensively than either type of peptides - to decipher a possible link between both amyloid pathology and antimicrobial activity, which can guide drug design and peptide engineering to influence peptide-membrane interactions important in human health and diseases.
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Affiliation(s)
- Mingzhen Zhang
- Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, Ohio 44325, USA.
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47
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Holmstrup M, Bouvrais H, Westh P, Wang C, Slotsbo S, Waagner D, Enggrob K, Ipsen JH. Lipophilic contaminants influence cold tolerance of invertebrates through changes in cell membrane fluidity. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:9797-9803. [PMID: 25050459 DOI: 10.1021/es502221g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Contaminants taken up by living organisms in the environment as a result of anthropogenic contamination can reduce the tolerance of natural stressors, e.g., low temperatures, but the physiological mechanisms behind these interactions of effects are poorly understood. The tolerance to low temperatures of organisms that cannot regulate their body temperature (ectotherms) depends on their ability to increase the fluidity of their cellular membranes at low temperatures. Our study shows that contaminants accumulating in lipids of organisms alter the physical state of their membranes simply by being present. Contaminants of varying chemical structures can alter the membrane fluidity in either direction and correspondingly modulate the cold tolerance of intact animals.
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Affiliation(s)
- Martin Holmstrup
- Department of Bioscience, Aarhus University , Vejlsøvej 25, DK-8600 Silkeborg, Denmark
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48
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Dimova R. Recent developments in the field of bending rigidity measurements on membranes. Adv Colloid Interface Sci 2014; 208:225-34. [PMID: 24666592 DOI: 10.1016/j.cis.2014.03.003] [Citation(s) in RCA: 326] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 02/28/2014] [Accepted: 03/02/2014] [Indexed: 12/19/2022]
Abstract
This review gives a brief overview of experimental approaches used to assess the bending rigidity of membranes. Emphasis is placed on techniques based on the use of giant unilamellar vesicles. We summarize the effect on the bending rigidity of membranes as a function of membrane composition, presence of various inclusions in the bilayer and molecules and ions in the bathing solutions. Examples for the impact of temperature, cholesterol, some peptides and proteins, sugars and salts are provided and the literature data are discussed critically. Future directions, open questions and possible developments in this research field are also included.
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Affiliation(s)
- Rumiana Dimova
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany.
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49
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Loftus AF, Noreng S, Hsieh VL, Parthasarathy R. Robust measurement of membrane bending moduli using light sheet fluorescence imaging of vesicle fluctuations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:14588-14594. [PMID: 24180269 DOI: 10.1021/la403837d] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The mechanical rigidity of lipid membranes is a key determinant of the energetics of cellular membrane deformation. Measurements of membrane bending moduli remain rare, however, and show a large variance, a situation that can be addressed by the development of improved techniques and by comparisons between disparate techniques applied to the same systems. We introduce here the use of selective plane illumination microscopy (SPIM, also known as light sheet fluorescence microscopy) to image thermal fluctuations of giant vesicles. The optical sectioning of SPIM enables high-speed fluorescence imaging of freely suspended vesicles and quantification of edge localization precision, yielding robust fluctuation spectra and rigidity estimates. For both lipid-only membranes and membranes bound by the intracellular trafficking protein Sar1p, which lowers membrane rigidity in a concentration-dependent manner, we show that the resulting bending modulus values are in close agreement with those derived from an independent assay based on membrane tether pulling. We also show that the fluctuation spectra of vesicles bound by the mammalian Sar1A protein, which stiffens membranes at high concentrations, are not well fit by a model of homogeneous quasi-spherical vesicles, suggesting that SPIM-based analysis can offer insights into spatially inhomogeneous properties induced by protein assemblies.
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Affiliation(s)
- Andrew F Loftus
- Department of Chemistry, ‡Department of Physics, and §Materials Science Institute, The University of Oregon , Eugene, Oregon 97403, United States
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50
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Ramesh P, Baroji YF, Reihani SNS, Stamou D, Oddershede LB, Bendix PM. FBAR syndapin 1 recognizes and stabilizes highly curved tubular membranes in a concentration dependent manner. Sci Rep 2013; 3:1565. [PMID: 23535634 PMCID: PMC3610093 DOI: 10.1038/srep01565] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 03/14/2013] [Indexed: 12/21/2022] Open
Abstract
Syndapin 1 FBAR, a member of the Bin-amphiphysin-Rvs (BAR) domain protein family, is known to induce membrane curvature and is an essential component in biological processes like endocytosis and formation and growth of neurites. We quantify the curvature sensing of FBAR on reconstituted porcine brain lipid vesicles and show that it senses membrane curvature at low density whereas it induces and reinforces tube stiffness at higher density. FBAR strongly up-concentrates on the high curvature tubes pulled out of Giant Unilamellar lipid Vesicles (GUVs), this sorting behavior is strongly amplified at low protein densities. Interestingly, FBAR from syndapin 1 has a large affinity for tubular membranes with curvatures larger than its own intrinsic concave curvature. Finally, we studied the effect of FBAR on membrane relaxation kinetics with high temporal resolution and found that the protein increases relaxation time of the tube holding force in a density-dependent fashion.
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Affiliation(s)
- Pradeep Ramesh
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen, Denmark
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