1
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Unveiling the mono-rhamnolipid and di-rhamnolipid mechanisms of action upon plasma membrane models. J Colloid Interface Sci 2022; 624:579-592. [DOI: 10.1016/j.jcis.2022.05.145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 05/24/2022] [Accepted: 05/25/2022] [Indexed: 11/18/2022]
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2
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Appshaw P, Seddon AM, Hanna S. Scale-invariance in miniature coarse-grained red blood cells by fluctuation analysis. SOFT MATTER 2022; 18:1747-1756. [PMID: 34994752 DOI: 10.1039/d1sm01542g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
To accurately represent the morphological and elastic properties of a human red blood cell, Fu et al. [Fu et al., Lennard-Jones type pair-potential method for coarse-grained lipid bilayer membrane simulations in LAMMPS, 2017, 210, 193-203] recently developed a coarse-grained molecular dynamics model with particular detail in the membrane. However, such a model accrues an extremely high computational cost for whole-cell simulation when assuming an appropriate length scaling - that of the bilayer thickness. To date, the model has only simulated "miniature" cells in order to circumvent this, with the a priori assumption that these miniaturised cells correctly represent their full-sized counterparts. The present work assesses the validity of this approach, by testing the scale invariance of the model through simulating cells of various diameters; first qualitatively in their shape evolution, then quantitatively by measuring their bending rigidity through fluctuation analysis. Cells of diameter of at least 0.5 μm were able to form the characteristic biconcave shape of human red blood cells, though smaller cells instead equilibrated to bowl-shaped stomatocytes. Thermal fluctuation analysis showed the bending rigidity to be constant over all cell sizes tested, and consistent between measurements on the whole-cell and on a planar section of bilayer. This is as expected from the theory on both counts. Therefore, we confirm that the evaluated model is a good representation of a full-size RBC when the model diameter is ≥0.5 μm, in terms of the morphological and mechanical properties investigated.
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Affiliation(s)
- Paul Appshaw
- School of Physics, HH Wills Physics Laboratory, University of Bristol, BS8 1TL, UK.
| | - Annela M Seddon
- Bristol Centre for Functional Nanomaterials, HH Wills Physics Laboratory, University of Bristol, BS8 1TL, UK
| | - Simon Hanna
- School of Physics, HH Wills Physics Laboratory, University of Bristol, BS8 1TL, UK.
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3
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The Effect of the Osmotically Active Compound Concentration Difference on the Passive Water and Proton Fluxes across a Lipid Bilayer. Int J Mol Sci 2021; 22:ijms222011099. [PMID: 34681757 PMCID: PMC8540289 DOI: 10.3390/ijms222011099] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/08/2021] [Accepted: 10/11/2021] [Indexed: 11/16/2022] Open
Abstract
The molecular details of the passive water flux across the hydrophobic membrane interior are still a matter of debate. One of the postulated mechanisms is the spontaneous, water-filled pore opening, which facilitates the hydrophilic connection between aqueous phases separated by the membrane. In the paper, we provide experimental evidence showing that the spontaneous lipid pore formation correlates with the membrane mechanics; hence, it depends on the composition of the lipid bilayer and the concentration of the osmotically active compound. Using liposomes as an experimental membrane model, osmotically induced water efflux was measured with the stopped-flow technique. Shapes of kinetic curves obtained at low osmotic pressure differences are interpreted in terms of two events: the lipid pore opening and water flow across the aqueous channel. The biological significance of the dependence of the lipid pore formation on the concentration difference of an osmotically active compound was illustrated by the demonstration that osmotically driven water flow can be accompanied by the dissipation of the pH gradient. The application of the Helfrich model to describe the probability of lipid pore opening was validated by demonstrating that the probability of pore opening correlates with the membrane bending rigidity. The correlation was determined by experimentally derived bending rigidity coefficients and probabilities of lipid pores opening.
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4
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Ip T, Li Q, Brooks N, Elani Y. Manufacture of Multilayered Artificial Cell Membranes through Sequential Bilayer Deposition on Emulsion Templates. Chembiochem 2021; 22:2275-2281. [PMID: 33617681 PMCID: PMC8360201 DOI: 10.1002/cbic.202100072] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Indexed: 12/21/2022]
Abstract
Efforts to manufacture artificial cells that replicate the architectures, processes and behaviours of biological cells are rapidly increasing. Perhaps the most commonly reconstructed cellular structure is the membrane, through the use of unilamellar vesicles as models. However, many cellular membranes, including bacterial double membranes, nuclear envelopes, and organelle membranes, are multilamellar. Due to a lack of technologies available for their controlled construction, multilayered membranes are not part of the repertoire of cell-mimetic motifs used in bottom-up synthetic biology. To address this, we developed emulsion-based technologies that allow cell-sized multilayered vesicles to be produced layer-by-layer, with compositional control over each layer, thus enabling studies that would otherwise remain inaccessible. We discovered that bending rigidities scale with the number of layers and demonstrate inter-bilayer registration between coexisting liquid-liquid domains. These technologies will contribute to the exploitation of multilayered membrane structures, paving the way for incorporating protein complexes that span multiple bilayers.
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Affiliation(s)
- Tsoi Ip
- Department of ChemistryImperial College LondonMolecular Sciences Research Hub White CityLondonW12 0BZUK
| | - Qien Li
- Department of ChemistryImperial College LondonMolecular Sciences Research Hub White CityLondonW12 0BZUK
| | - Nick Brooks
- Department of ChemistryImperial College LondonMolecular Sciences Research Hub White CityLondonW12 0BZUK
| | - Yuval Elani
- Department of Chemical EngineeringImperial College London South KensingtonLondonSW7 2AZUK
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5
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Effect of Amyloid-β Monomers on Lipid Membrane Mechanical Parameters-Potential Implications for Mechanically Driven Neurodegeneration in Alzheimer's Disease. Int J Mol Sci 2020; 22:ijms22010018. [PMID: 33375009 PMCID: PMC7792773 DOI: 10.3390/ijms22010018] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/17/2020] [Accepted: 12/17/2020] [Indexed: 01/21/2023] Open
Abstract
Alzheimer’s disease (AD) is a neurodegenerative disease that results in memory loss and the impairment of cognitive skills. Several mechanisms of AD’s pathogenesis were proposed, such as the progressive accumulation of amyloid-β (Aβ) and τ pathology. Nevertheless, the exact neurodegenerative mechanism of the Aβ remains complex and not fully understood. This paper proposes an alternative hypothesis of the mechanism based on maintaining the neuron membrane’s mechanical balance. The incorporation of Aβ decreases the lipid membrane’s elastic properties, which eventually leads to the impairment of membrane clustering, disruption of mechanical wave propagation, and change in gamma oscillations. The first two disrupt the neuron’s ability to function correctly while the last one decreases sensory encoding and perception enabling. To begin discussing this mechanical-balance hypothesis, we measured the effect of two selected peptides, Aβ-40 and Aβ-42, as well as their fluorescently labeled modification, on membrane mechanical properties. The decrease of bending rigidity, consistent for all investigated peptides, was observed using molecular dynamic studies and experimental flicker-noise techniques. Additionally, wave propagation was investigated with molecular dynamic studies in membranes with and without incorporated neurodegenerative peptides. A change in membrane behavior was observed in the membrane system with incorporated Aβ.
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6
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Affiliation(s)
- Chandra Has
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India
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7
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Spanke HT, Style RW, François-Martin C, Feofilova M, Eisentraut M, Kress H, Agudo-Canalejo J, Dufresne ER. Wrapping of Microparticles by Floppy Lipid Vesicles. PHYSICAL REVIEW LETTERS 2020; 125:198102. [PMID: 33216584 DOI: 10.1103/physrevlett.125.198102] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/13/2020] [Indexed: 06/11/2023]
Abstract
Lipid membranes, the barrier defining living cells and many of their subcompartments, bind to a wide variety of nano- and micrometer sized objects. In the presence of strong adhesive forces, membranes can strongly deform and wrap the particles, an essential step in crossing the membrane for a variety of healthy and disease-related processes. A large body of theoretical and numerical work has focused on identifying the physical properties that underly wrapping. Using a model system of micron-sized colloidal particles and giant unilamellar lipid vesicles with tunable adhesive forces, we measure a wrapping phase diagram and make quantitative comparisons to theoretical models. Our data are consistent with a model of membrane-particle interactions accounting for the adhesive energy per unit area, membrane bending rigidity, particle size, and vesicle radius.
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Affiliation(s)
| | | | | | | | - Manuel Eisentraut
- Department of Physics, University of Bayreuth, 95447 Bayreuth, Germany
| | - Holger Kress
- Department of Physics, University of Bayreuth, 95447 Bayreuth, Germany
| | - Jaime Agudo-Canalejo
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen, Germany
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8
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Faizi HA, Reeves CJ, Georgiev VN, Vlahovska PM, Dimova R. Fluctuation spectroscopy of giant unilamellar vesicles using confocal and phase contrast microscopy. SOFT MATTER 2020; 16:8996-9001. [PMID: 32966528 DOI: 10.1039/d0sm00943a] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A widely used method to measure the bending rigidity of bilayer membranes is fluctuation spectroscopy, which analyses the thermally-driven membrane undulations of giant unilamellar vesicles recorded with either phase-contrast or confocal microscopy. Here, we analyze the fluctuations of the same vesicle using both techniques and obtain consistent values for the bending modulus. We discuss the factors that may lead to discrepancies.
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Affiliation(s)
- Hammad A Faizi
- Department of Mechanical Engineering, McCormick School of Engineering and Applied Science, Northwestern University, Evanston, Illinois 60208, USA. and Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany.
| | - Cody J Reeves
- Department of Engineering Sciences and Applied Mathematics, McCormick School of Engineering and Applied Science, Northwestern University, Evanston, Illinois 60208, USA
| | - Vasil N Georgiev
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany.
| | - Petia M Vlahovska
- Department of Mechanical Engineering, McCormick School of Engineering and Applied Science, Northwestern University, Evanston, Illinois 60208, USA. and Department of Engineering Sciences and Applied Mathematics, McCormick School of Engineering and Applied Science, Northwestern University, Evanston, Illinois 60208, USA
| | - Rumiana Dimova
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany.
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9
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Marušič N, Otrin L, Zhao Z, Lira RB, Kyrilis FL, Hamdi F, Kastritis PL, Vidaković-Koch T, Ivanov I, Sundmacher K, Dimova R. Constructing artificial respiratory chain in polymer compartments: Insights into the interplay between bo3 oxidase and the membrane. Proc Natl Acad Sci U S A 2020; 117:15006-15017. [PMID: 32554497 PMCID: PMC7334566 DOI: 10.1073/pnas.1919306117] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Cytochrome bo3 ubiquinol oxidase is a transmembrane protein, which oxidizes ubiquinone and reduces oxygen, while pumping protons. Apart from its combination with F1Fo-ATPase to assemble a minimal ATP regeneration module, the utility of the proton pump can be extended to other applications in the context of synthetic cells such as transport, signaling, and control of enzymatic reactions. In parallel, polymers have been speculated to be phospholipid mimics with respect to their ability to self-assemble in compartments with increased stability. However, their usability as interfaces for complex membrane proteins has remained questionable. In the present work, we optimized a fusion/electroformation approach to reconstitute bo3 oxidase in giant unilamellar vesicles made of PDMS-g-PEO and/or phosphatidylcholine (PC). This enabled optical access, while microfluidic trapping allowed for online analysis of individual vesicles. The tight polymer membranes and the inward oriented enzyme caused 1 pH unit difference in 30 min, with an initial rate of 0.35 pH·min-1 To understand the interplay in these composite systems, we studied the relevant mechanical and rheological membrane properties. Remarkably, the proton permeability of polymer/lipid hybrids decreased after protein insertion, while the latter also led to a 20% increase of the polymer diffusion coefficient in polymersomes. In addition, PDMS-g-PEO increased the activity lifetime and the resistance to free radicals. These advantageous properties may open diverse applications, ranging from cell-free biotechnology to biomedicine. Furthermore, the presented study serves as a comprehensive road map for studying the interactions between membrane proteins and synthetic membranes, which will be fundamental for the successful engineering of such hybrid systems.
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Affiliation(s)
- Nika Marušič
- Process Systems Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany
| | - Lado Otrin
- Electrochemical Energy Conversion, Max Planck Institute for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany
| | - Ziliang Zhao
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Rafael B Lira
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Fotis L Kyrilis
- Interdisciplinary Research Center HALOmem, Martin Luther University Halle-Wittenberg, 06120 Halle/Saale, Germany
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, 06120 Halle/Saale, Germany
| | - Farzad Hamdi
- Interdisciplinary Research Center HALOmem, Martin Luther University Halle-Wittenberg, 06120 Halle/Saale, Germany
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, 06120 Halle/Saale, Germany
| | - Panagiotis L Kastritis
- Interdisciplinary Research Center HALOmem, Martin Luther University Halle-Wittenberg, 06120 Halle/Saale, Germany
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, 06120 Halle/Saale, Germany
| | - Tanja Vidaković-Koch
- Electrochemical Energy Conversion, Max Planck Institute for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany;
| | - Ivan Ivanov
- Process Systems Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany;
| | - Kai Sundmacher
- Process Systems Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany
| | - Rumiana Dimova
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
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10
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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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11
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Takatori SC, Sahu A. Active Contact Forces Drive Nonequilibrium Fluctuations in Membrane Vesicles. PHYSICAL REVIEW LETTERS 2020; 124:158102. [PMID: 32357050 DOI: 10.1103/physrevlett.124.158102] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 03/20/2020] [Indexed: 05/24/2023]
Abstract
We analyze the nonequilibrium shape fluctuations of giant unilamellar vesicles encapsulating motile bacteria. Owing to bacteria-membrane collisions, we experimentally observe a significant increase in the magnitude of membrane fluctuations at low wave numbers, compared to the well-known thermal fluctuation spectrum. We interrogate these results by numerically simulating membrane height fluctuations via a modified Langevin equation, which includes bacteria-membrane contact forces. Taking advantage of the lengthscale and timescale separation of these contact forces and thermal noise, we further corroborate our results with an approximate theoretical solution to the dynamical membrane equations. Our theory and simulations demonstrate excellent agreement with nonequilibrium fluctuations observed in experiments. Moreover, our theory reveals that the fluctuation-dissipation theorem is not broken by the bacteria; rather, membrane fluctuations can be decomposed into thermal and active components.
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Affiliation(s)
- Sho C Takatori
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA
| | - Amaresh Sahu
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA
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12
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Drabik D, Chodaczek G, Kraszewski S, Langner M. Mechanical Properties Determination of DMPC, DPPC, DSPC, and HSPC Solid-Ordered Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:3826-3835. [PMID: 32176506 PMCID: PMC7467745 DOI: 10.1021/acs.langmuir.0c00475] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Lipid bilayers are active participants in many crucial biological processes. They can be observed in different phases, liquid and solid, respectively. The liquid phase is predominant in biological systems. The solid phase, both crystalline and gel phases, is under investigation due to its resilience to mechanical stress and tight packing of lipids. The mechanical properties of lipids affect their dynamics, therefore influencing the transformation of cell plasma and the endomembrane. Mechanical properties of lipid bilayers are also an important parameter in the design and production of supramolecular lipid-based drug delivery systems. To this end, in this work, we focused on investigating the effect of solid phases of lipid bilayers on their structural parameters and mechanical properties using theoretical molecular dynamics studies on atomistic models of whole vesicles. Those include area per lipid, membrane thickness, density vesicle profiles, bending rigidity coefficient, and area compressibility. Additionally, the bending rigidity coefficient was measured using the flicker noise spectroscopy. The two approaches produced very similar and consistent results. We showed that, contrary to our expectations, bending rigidity coefficients of solid-ordered bilayers for vesicles decreased with an increase in lipid transition temperature. This tendency was reverse in planar systems. Additionally, we have observed an increase of membrane thickness and area compressibility and a decrease of area per lipid. We hope these results will provide valuable mechanical insight for the behavior in solid phases and differences between spherical and planar confirmations.
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Affiliation(s)
- Dominik Drabik
- Department of Biomedical
Engineering, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Pl. Grunwaldzki 13, 50-377 Wrocław, Poland
| | - Grzegorz Chodaczek
- PORT − Polish Center for Technology Development, Stabłowicka 147, 54-066 Wrocław, Poland
| | - Sebastian Kraszewski
- Department of Biomedical
Engineering, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Pl. Grunwaldzki 13, 50-377 Wrocław, Poland
| | - Marek Langner
- Department of Biomedical
Engineering, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Pl. Grunwaldzki 13, 50-377 Wrocław, Poland
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13
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Kumar D, Richter CM, Schroeder CM. Conformational dynamics and phase behavior of lipid vesicles in a precisely controlled extensional flow. SOFT MATTER 2020; 16:337-347. [PMID: 31802095 DOI: 10.1039/c9sm02048a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Lipid vesicles play a key role in fundamental biological processes. Despite recent progress, we lack a complete understanding of the non-equilibrium dynamics of vesicles due to challenges associated with long-time observation of shape fluctuations in strong flows. In this work, we present a flow-phase diagram for vesicle shape and conformational transitions in planar extensional flow using a Stokes trap, which enables control over the center-of-mass position of single or multiple vesicles in precisely defined flows [A. Shenoy, C. V. Rao and C. M. Schroeder, Proc. Natl. Acad. Sci. U. S. A., 2016, 113(15), 3976-3981]. In this way, we directly observe the non-equilibrium conformations of lipid vesicles as a function of reduced volume ν, capillary number Ca, and viscosity contrast λ. Our results show that vesicle dynamics in extensional flow are characterized by the emergence of three distinct shape transitions, including a tubular to symmetric dumbbell transition, a spheroid to asymmetric dumbbell transition, and quasi-spherical to ellipsoid transition. The experimental phase diagram is in good agreement with recent predictions from simulations [V. Narsimhan, A. P. Spann and E. S. Shaqfeh, J. Fluid Mech., 2014, 750, 144]. We further show that the phase boundary of vesicle shape transitions is independent of the viscosity contrast. Taken together, our results demonstrate the utility of the Stokes trap for the precise quantification of vesicle stretching dynamics in precisely defined flows.
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Affiliation(s)
- Dinesh Kumar
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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14
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Mesarec L, Góźdź W, Iglič A, Kralj-Iglič V, Virga EG, Kralj S. Normal red blood cells' shape stabilized by membrane's in-plane ordering. Sci Rep 2019; 9:19742. [PMID: 31875042 PMCID: PMC6930264 DOI: 10.1038/s41598-019-56128-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 12/04/2019] [Indexed: 11/19/2022] Open
Abstract
Red blood cells (RBCs) are present in almost all vertebrates and their main function is to transport oxygen to the body tissues. RBCs' shape plays a significant role in their functionality. In almost all mammals in normal conditions, RBCs adopt a disk-like (discocyte) shape, which optimizes their flow properties in vessels and capillaries. Experimentally measured values of the reduced volume (v) of stable discocyte shapes range in a relatively broad window between v ~ 0.58 and 0.8. However, these observations are not supported by existing theoretical membrane-shape models, which predict that discocytic RBC shape is stable only in a very narrow interval of v values, ranging between v ~ 0.59 and 0.65. In this study, we demonstrate that this interval is broadened if a membrane's in-plane ordering is taken into account. We model RBC structures by using a hybrid Helfrich-Landau mesoscopic approach. We show that an extrinsic (deviatoric) curvature free energy term stabilizes the RBC discocyte shapes. In particular, we show on symmetry grounds that the role of extrinsic curvature is anomalously increased just below the nematic in-plane order-disorder phase transition temperature.
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Affiliation(s)
- L Mesarec
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, 1000, Ljubljana, Slovenia
| | - W Góźdź
- Institute of Physical Chemistry, Polish Academy of Sciences, 01-224, Warsaw, Poland
| | - A Iglič
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, 1000, Ljubljana, Slovenia
- Laboratory of Mass Spectrometry and Proteomics, Institute of Biosciences and BioResources, National Research Council of Italy, Napoli, 80132, Italy
| | - V Kralj-Iglič
- Laboratory of Mass Spectrometry and Proteomics, Institute of Biosciences and BioResources, National Research Council of Italy, Napoli, 80132, Italy
- Laboratory of Clinical Biophysics, Faculty of Health Sciences, University of Ljubljana, 1000, Ljubljana, Slovenia
- Laboratory of Clinical Biophysics, Faculty of Medicine, University of Ljubljana, 1000, Ljubljana, Slovenia
| | - E G Virga
- Department of Mathematics, University of Pavia, Via Ferrata 5, 27100, Pavia, Italy
| | - S Kralj
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, 2000, Maribor, Slovenia.
- Condensed Matter Physics Department, Jožef Stefan Institute, 1000, Ljubljana, Slovenia.
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15
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Perez-Lopez MI, Mendez-Reina R, Trier S, Herrfurth C, Feussner I, Bernal A, Forero-Shelton M, Leidy C. Variations in carotenoid content and acyl chain composition in exponential, stationary and biofilm states of Staphylococcus aureus, and their influence on membrane biophysical properties. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:978-987. [PMID: 30771288 DOI: 10.1016/j.bbamem.2019.02.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 02/01/2019] [Accepted: 02/04/2019] [Indexed: 01/01/2023]
Abstract
Bacteria are often found in close association with surfaces, resulting in the formation of biofilms. In Staphylococcus aureus (S. aureus), biofilms are implicated in the resilience of chronic infections, presenting a serious clinical problem world-wide. Here, S. aureus biofilms are grown under flow within clinical catheters at 37 °C. The lipid composition and biophysical properties of lipid extracts from these biofilms are compared with those from exponential growth and stationary phase cells. Biofilms show a reduction in iso and anteiso branching compensated by an increase in saturated fatty acids compared to stationary phase. A drastic reduction in carotenoid levels is also observed during biofilm formation. Thermotropic measurements of Laurdan GP and DPH polarization, show a reduction of lipid packing at 37 °C for biofilms compared to stationary phase. We studied the effects of carotenoid content on DMPG and DPPG model membranes showing trends in thermotropic behavior consistent with those observed in bacterial isolates, indicating that carotenoids participate in modulating lipid packing. Additionally, bending elastic constant (kc) measurements using vesicle fluctuation analysis (VFA) show that the presence of carotenoids can increase membrane bending rigidity. The antimicrobial peptide Magainin H2 was less activity on liposomes composed of stationary phase compared to biofilms or exponential growth isolates. This study contributes to an understanding of how Staphylococcus aureus modulates the composition of its membrane lipids, and how those changes affect the biophysical properties of membranes, which in turn may play a role in its virulence and its resistance to different membrane-active antimicrobial agents.
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Affiliation(s)
- Maria Isabel Perez-Lopez
- Department of Physics, Universidad de los Andes, Bogotá, Colombia; Biological Sciences Department, Universidad de los Andes, Bogotá, Colombia
| | | | - Steve Trier
- Department of Physics, Universidad de los Andes, Bogotá, Colombia
| | - Cornelia Herrfurth
- Department of Plant Biochemistry, Albrecht-von-Haller Institute for Plant Sciences, University of Goettingen, Goettingen, Germany
| | - Ivo Feussner
- Department of Plant Biochemistry, Albrecht-von-Haller Institute for Plant Sciences, University of Goettingen, Goettingen, Germany; Department of Plant Biochemistry, Goettingen Center for Molecular Biosciences (GZMB), University of Goettingen, Goettingen, Germany
| | - Adriana Bernal
- Biological Sciences Department, Universidad de los Andes, Bogotá, Colombia
| | | | - Chad Leidy
- Department of Physics, Universidad de los Andes, Bogotá, Colombia.
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16
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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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17
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Doskocz J, Drabik D, Chodaczek G, Przybyło M, Langner M. Statistical Analysis of Bending Rigidity Coefficient Determined Using Fluorescence-Based Flicker-Noise Spectroscopy. J Membr Biol 2018; 251:601-608. [PMID: 29858612 DOI: 10.1007/s00232-018-0037-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 05/29/2018] [Indexed: 10/14/2022]
Abstract
Bending rigidity coefficient describes propensity of a lipid bilayer to deform. In order to measure the parameter experimentally using flickering noise spectroscopy, the microscopic imaging is required, which necessitates the application of giant unilamellar vesicles (GUV) lipid bilayer model. The major difficulty associated with the application of the model is the statistical character of GUV population with respect to their size and the homogeneity of lipid bilayer composition, if a mixture of lipids is used. In the paper, the bending rigidity coefficient was measured using the fluorescence-enhanced flicker-noise spectroscopy. In the paper, the bending rigidity coefficient was determined for large populations of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and 1,2-dioleoyl-sn-glycero-3-phosphocholine vesicles. The quantity of obtained experimental data allows to perform statistical analysis aiming at the identification of the distribution, which is the most appropriate for the calculation of the value of the membrane bending rigidity coefficient. It has been demonstrated that the bending rigidity coefficient is characterized by an asymmetrical distribution, which is well approximated with the gamma distribution. Since there are no biophysical reasons for that we propose to use the difference between normal and gamma fits as a measure of the homogeneity of vesicle population. In addition, the effect of a fluorescent label and types of instrumental setups on determined values has been tested. Obtained results show that the value of the bending rigidity coefficient does not depend on the type of a fluorescent label nor on the type of microscope used.
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Affiliation(s)
- Joanna Doskocz
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Pl. Grunwaldzki 13, 50-377, Wrocław, Poland.
| | - Dominik Drabik
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Pl. Grunwaldzki 13, 50-377, Wrocław, Poland
| | - Grzegorz Chodaczek
- Wroclaw Research Centre EIT+, ul. Stabłowicka 147, 54-066, Wrocław, Poland
| | - Magdalena Przybyło
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Pl. Grunwaldzki 13, 50-377, Wrocław, Poland.,Lipid Systems sp. z o.o., ul. Krzemieniecka 48C, 54-613, Wrocław, Poland
| | - Marek Langner
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Pl. Grunwaldzki 13, 50-377, Wrocław, Poland.,Lipid Systems sp. z o.o., ul. Krzemieniecka 48C, 54-613, Wrocław, Poland
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18
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Moleiro L, Mell M, Bocanegra R, López-Montero I, Fouquet P, Hellweg T, Carrascosa J, Monroy F. Permeability modes in fluctuating lipid membranes with DNA-translocating pores. Adv Colloid Interface Sci 2017; 247:543-554. [PMID: 28735883 DOI: 10.1016/j.cis.2017.07.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 07/10/2017] [Accepted: 07/10/2017] [Indexed: 10/19/2022]
Abstract
Membrane pores can significantly alter not only the permeation dynamics of biological membranes but also their elasticity. Large membrane pores able to transport macromolecular contents represent an interesting model to test theoretical predictions that assign active-like (non-equilibrium) behavior to the permeability contributions to the enhanced membrane fluctuations existing in permeable membranes [Maneville et al. Phys. Rev. Lett. 82, 4356 (1999)]. Such high-amplitude active contributions arise from the forced transport of solvent and solutes through the open pores, which becomes even dominant at large permeability. In this paper, we present a detailed experimental analysis of the active shape fluctuations that appear in highly permeable lipid vesicles with large macromolecular pores inserted in the lipid membrane, which are a consequence of transport permeability events occurred in an osmotic gradient. The experimental results are found in quantitative agreement with theory, showing a remarkable dependence with the density of membrane pores and giving account of mechanical compliances and permeability rates that are compatible with the large size of the membrane pore considered. The presence of individual permeation events has been detected in the fluctuation time-series, from which a stochastic distribution of the permeation events compatible with a shot-noise has been deduced. The non-equilibrium character of the membrane fluctuations in a permeation field, even if the membrane pores are mere passive transporters, is clearly demonstrated. Finally, a bio-nano-technology outlook of the proposed synthetic concept is given on the context of prospective uses as active membrane DNA-pores exploitable in gen-delivery applications based on lipid vesicles.
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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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20
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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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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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22
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Yu M, Lira RB, Riske KA, Dimova R, Lin H. Ellipsoidal Relaxation of Deformed Vesicles. PHYSICAL REVIEW LETTERS 2015; 115:128303. [PMID: 26431021 DOI: 10.1103/physrevlett.115.128303] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Indexed: 06/05/2023]
Abstract
Theoretical analysis and experimental quantification on the ellipsoidal relaxation of vesicles are presented. The current work reveals the simplicity and universal aspects of this process. The Helfrich formula is shown to apply to the dynamic relaxation of moderate-to-high tension membranes, and a closed-form solution is derived which predicts the vesicle aspect ratio as a function of time. Scattered data are unified by a time scale, which leads to a similarity behavior, governed by a distinctive solution for each vesicle type. Two separate regimes in the relaxation are identified, namely, the "entropic" and the "constant-tension" regimes. The bending rigidity and the initial membrane tension can be simultaneously extracted from the data analysis, posing the current approach as an effective means for the mechanical analysis of biomembranes.
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Affiliation(s)
- Miao Yu
- Department of Mechanical and Aerospace Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854, USA
| | - Rafael B Lira
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany
- Departamento de Biofísica, Universidade Federal de São Paulo, BR-04044020 São Paulo, Brazil
| | - Karin A Riske
- Departamento de Biofísica, Universidade Federal de São Paulo, BR-04044020 São Paulo, Brazil
| | - Rumiana Dimova
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany
| | - Hao Lin
- Department of Mechanical and Aerospace Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854, USA
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23
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Fisker KV, Bouvrais H, Overgaard J, Schöttner K, Ipsen JH, Holmstrup M. Membrane properties of Enchytraeus albidus originating from contrasting environments: a comparative analysis. J Comp Physiol B 2015; 185:389-400. [DOI: 10.1007/s00360-015-0895-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 12/11/2014] [Accepted: 01/22/2015] [Indexed: 01/02/2023]
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24
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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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25
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Yamada A, Lee S, Bassereau P, Baroud CN. Trapping and release of giant unilamellar vesicles in microfluidic wells. SOFT MATTER 2014; 10:5878-85. [PMID: 24930637 DOI: 10.1039/c4sm00065j] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We describe the trapping and release of giant unilamellar vesicles (GUVs) in a thin and wide microfluidic channel, as they cross indentations etched in the channel ceiling. This trapping results from the reduction of the membrane elastic energy, which is stored in the GUV as it squeezes to enter into the thin channel. We demonstrate that GUVs whose diameter is slightly larger than the channel height can be trapped and that they can be untrapped by flowing the outer fluid beyond a critical velocity. GUVs smaller than the channel height flow undisturbed while those much larger cannot squeeze into the thin regions. Within the range that allows trapping, larger GUVs are anchored more strongly than smaller GUVs. The ability to trap vesicles provides optical access to the GUVs for extended periods of time; this allows the observation of recirculation flows on the surface of the GUVs, in the forward direction near the mid-plane of the channel and in the reverse direction elsewhere. We also obtain the shape of GUVs under different flow conditions through confocal microscopy. This geometric information is used to derive a mechanical model of the force balance that equates the viscous effects from the outer flow with the elastic effects based on the variation of the membrane stretching energy. This model yields good agreement with the experimental data when values of the stretching moduli are taken from the scientific literature. This microfluidic approach provides a new way of storing a large number of GUVs at specific locations, with or without the presence of an outer flow. As such, it constitutes a high-throughput alternative to micropipette manipulation of individual GUVs for chemical or biological applications.
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Affiliation(s)
- Ayako Yamada
- Institut Curie, Centre de Recherche; CNRS, UMR168; Université Pierre et Marie Curie; Labex CelTisPhyBio and Paris Sciences et Lettres, F-75248 Paris Cedex 05, France.
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27
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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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28
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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: 307] [Impact Index Per Article: 30.7] [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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Bassereau P, Sorre B, Lévy A. Bending lipid membranes: experiments after W. Helfrich's model. Adv Colloid Interface Sci 2014; 208:47-57. [PMID: 24630341 DOI: 10.1016/j.cis.2014.02.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 02/02/2014] [Accepted: 02/03/2014] [Indexed: 10/25/2022]
Abstract
Current description of biomembrane mechanics originates for a large part from W. Helfrich's model. Based on his continuum theory, many experiments have been performed in the past four decades on simplified membranes in order to characterize the mechanical properties of lipid membranes and the contribution of polymers or proteins. The long-term goal was to develop a better understanding of the mechanical properties of cell membranes. In this paper, we will review representative experimental approaches that were developed during this period and the main results that were obtained.
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Bouvrais H, Duelund L, Ipsen JH. Buffers affect the bending rigidity of model lipid membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:13-6. [PMID: 24377876 DOI: 10.1021/la403565f] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
In biophysical and biochemical studies of lipid bilayers the influence of the used buffer is often ignored or assumed to be negligible on membrane structure, elasticity, or physical properties. However, we here present experimental evidence, through bending rigidity measurements performed on giant vesicles, of a more complex behavior, where the buffering molecules may considerably affect the bending rigidity of phosphatidylcholine bilayers. Furthermore, a synergistic effect on the bending modulus is observed in the presence of both salt and buffer molecules, which serves as a warning to experimentalists in the data interpretation of their studies, since typical lipid bilayer studies contain buffer and ion molecules.
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Affiliation(s)
- Hélène Bouvrais
- Department of Physics, Chemistry and Pharmacy, MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark , Campusvej 55, 5230 Odense M, Denmark
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Santhosh PB, Velikonja A, Perutkova Š, Gongadze E, Kulkarni M, Genova J, Eleršič K, Iglič A, Kralj-Iglič V, Ulrih NP. Influence of nanoparticle-membrane electrostatic interactions on membrane fluidity and bending elasticity. Chem Phys Lipids 2013; 178:52-62. [PMID: 24309194 DOI: 10.1016/j.chemphyslip.2013.11.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 11/21/2013] [Accepted: 11/22/2013] [Indexed: 11/18/2022]
Abstract
The aim of this work is to investigate the effect of electrostatic interactions between the nanoparticles and the membrane lipids on altering the physical properties of the liposomal membrane such as fluidity and bending elasticity. For this purpose, we have used nanoparticles and lipids with different surface charges. Positively charged iron oxide (γ-Fe2O3) nanoparticles, neutral and negatively charged cobalt ferrite (CoFe2O4) nanoparticles were encapsulated in neutral lipid 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine and negatively charged 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine lipid mixture. Membrane fluidity was assessed through the anisotropy measurements using the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene. Though the interaction of both the types of nanoparticles reduced the membrane fluidity, the results were more pronounced in the negatively charged liposomes encapsulated with positively charged iron oxide nanoparticles due to strong electrostatic attractions. X-ray photoelectron spectroscopy results also confirmed the presence of significant quantity of positively charged iron oxide nanoparticles in negatively charged liposomes. Through thermally induced shape fluctuation measurements of the giant liposomes, a considerable reduction in the bending elasticity modulus was observed for cobalt ferrite nanoparticles. The experimental results were supported by the simulation studies using modified Langevin-Poisson-Boltzmann model.
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Affiliation(s)
- Poornima Budime Santhosh
- Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia
| | - Aljaž Velikonja
- Laboratory of Biocybernetics, Faculty of Electrical Engineering, University of Ljubljana, Tržaska 25, SI-1000 Ljubljana, Slovenia; SMARTEH Research and Development of Electronic Controlling and Regulating Systems, Trg Tigrovcev 1, SI-5220 Tolmin, Slovenia
| | - Šarka Perutkova
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Tržaska 25, SI-1000 Ljubljana, Slovenia; Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Lipičeva 2, SI-1000 Ljubljana, Slovenia
| | - Ekaterina Gongadze
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Tržaska 25, SI-1000 Ljubljana, Slovenia
| | - Mukta Kulkarni
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Tržaska 25, SI-1000 Ljubljana, Slovenia
| | - Julia Genova
- Institute of Solid State Physics, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria
| | | | - Aleš Iglič
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Tržaska 25, SI-1000 Ljubljana, Slovenia
| | - Veronika Kralj-Iglič
- Laboratory of Clinical Biophysics, Faculty of Health Sciences, University of Ljubljana, Vrazov trg 2, SI-1000 Ljubljana, Slovenia
| | - Nataša Poklar Ulrih
- Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia; Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins (CipKeBiP), Jamova 39, SI-1000 Ljubljana, Slovenia.
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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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Solmaz ME, Sankhagowit S, Biswas R, Mejia CA, Povinelli ML, Malmstadt N. Optical stretching as a tool to investigate the mechanical properties of lipid bilayers. RSC Adv 2013; 3:10.1039/C3RA42510J. [PMID: 24244843 PMCID: PMC3827026 DOI: 10.1039/c3ra42510j] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Measurements of lipid bilayer bending modulus by various techniques produce widely divergent results. We attempt to resolve some of this ambiguity by measuring bending modulus in a system that can rapidly process large numbers of samples, yielding population statistics. This system is based on optical stretching of giant unilamellar vesicles (GUVs) in a microfluidic dual-beam optical trap (DBOT). The microfluidic DBOT system is used here to measure three populations of GUVs with distinct lipid compositions. We find that gel-phase membranes are significantly stiffer than liquid-phase membranes, consistent with previous reports. We also find that the addition of cholesterol does not alter the bending modulus of membranes composed of a monounsaturated phospholipid.
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Affiliation(s)
- Mehmet E. Solmaz
- Ming Hsieh Department of Electrical Engineering, University of Southern California, 3737 Watt Way, PHE 614, Los Angeles, CA 90089-0271, USA
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, 925 Bloom Walk, HED 216, Los Angeles, CA 90089-1211, USA
| | - Shalene Sankhagowit
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, 925 Bloom Walk, HED 216, Los Angeles, CA 90089-1211, USA
| | - Roshni Biswas
- Ming Hsieh Department of Electrical Engineering, University of Southern California, 3737 Watt Way, PHE 614, Los Angeles, CA 90089-0271, USA
| | - Camilo A. Mejia
- Ming Hsieh Department of Electrical Engineering, University of Southern California, 3737 Watt Way, PHE 614, Los Angeles, CA 90089-0271, USA
| | - Michelle L. Povinelli
- Ming Hsieh Department of Electrical Engineering, University of Southern California, 3737 Watt Way, PHE 614, Los Angeles, CA 90089-0271, USA
| | - Noah Malmstadt
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, 925 Bloom Walk, HED 216, Los Angeles, CA 90089-1211, USA
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Genova J, Vitkova V, Bivas I. Registration and analysis of the shape fluctuations of nearly spherical lipid vesicles. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:022707. [PMID: 24032864 DOI: 10.1103/physreve.88.022707] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Indexed: 06/02/2023]
Abstract
The analysis of shape fluctuations of giant nearly spherical lipid vesicles observed via optical microscopy is one of the widely used methods for the determination of the bending elasticity of lipid membranes. Although the method has been used already for three decades, the values of this material constant, obtained by different groups for membranes of the same composition, in identical conditions, differ significantly. The aim of the present work is the development of the method, enabling us to avoid the influence of artifacts on the value of the measured bending modulus. This is achieved by rejection of some images of the vesicle or the whole vesicle when they do not satisfy the requirements (selection criteria) of the applied theory. The bending modulus of 1-stearoyl-2-oleoyl-sn-glycerol-3-phosphocholine lipid membranes is determined via the advanced method described here. The results are compared with the values in the literature and their difference is discussed.
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Affiliation(s)
- Julia Genova
- Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Boulevard, Sofia 1784, Bulgaria
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Bouvrais H, Holmstrup M, Westh P, Ipsen JH. Analysis of the shape fluctuations of reconstituted membranes using GUVs made from lipid extracts of invertebrates. Biol Open 2013; 2:373-8. [PMID: 23616921 PMCID: PMC3625865 DOI: 10.1242/bio.20133434] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 01/02/2013] [Indexed: 11/21/2022] Open
Abstract
Changes in the physical properties of the lipid matrix of cell membranes have repeatedly been proposed to underlie stresses associated with e.g. drought, cold and xenobiotics. Therefore, the ability to experimentally monitor such properties is central to the fundamental physiological understanding of adaptive changes. Here, we test the analysis of shape fluctuations in membranes composed of lipid extracts from two soil invertebrates, and show that theories and experimental approaches previously developed for simpler liposomes may be applied directly to reconstituted membrane lipids. Specifically, we show how the bending rigidity of giant unilamellar liposomes of lipid extracts can be determined precisely. We suggest that future measurements of this parameter could elucidate mechanisms of adaptive processes such as changes in lipid composition and accumulation of protective osmolytes.
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Affiliation(s)
- Hélène Bouvrais
- Department of Physics, Chemistry and Pharmacy, MEMPHYS - Center for Biomembrane Physics, University of Southern Denmark , DK-5230 Odense M , Denmark
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Overview of a Quest for Bending Elasticity Measurement. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/b978-0-12-411516-3.00003-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Abstract
One of the many aspects of membrane biophysics dealt with in this Faraday Discussion regards the material moduli that describe energies at a supramolecular level. This introductory lecture first critically reviews differences in reported numerical values of the bending modulus K(C), which is a central property for the biologically important flexibility of membranes. It is speculated that there may be a reason that the shape analysis method tends to give larger values of K(C) than the micromechanical manipulation method or the more recent X-ray method that agree very well with each other. Another theme of membrane biophysics is the use of simulations to provide exquisite detail of structures and processes. This lecture critically reviews the application of atomic level simulations to the quantitative structure of simple single component lipid bilayers and diagnostics are introduced to evaluate simulations. Another theme of this Faraday Discussion was lateral heterogeneity in biomembranes with many different lipids. Coarse grained simulations and analytical theories promise to synergistically enhance experimental studies when their interaction parameters are tuned to agree with experimental data, such as the slopes of experimental tie lines in ternary phase diagrams. Finally, attention is called to contributions that add relevant biological molecules to bilayers and to contributions that study the exciting shape changes and different non-bilayer structures with different lipids.
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Affiliation(s)
- John F Nagle
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
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Intrinsic reaction-cycle time scale of Na+,K+-ATPase manifests itself in the lipid-protein interactions of nonequilibrium membranes. Proc Natl Acad Sci U S A 2012; 109:18442-6. [PMID: 23093677 DOI: 10.1073/pnas.1209909109] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Interaction between integral membrane proteins and the lipid-bilayer component of biological membranes is expected to mutually influence the proteins and the membrane. We present quantitative evidence of a manifestation of the lipid-protein interactions in liposomal membranes, reconstituted with actively pumping Na(+),K(+)-ATPase, in terms of nonequilibrium shape fluctuations that contain a relaxation time, τ, which is robust and independent of the specific fluctuation modes of the membrane. In the case of pumping Na(+)-ions, analysis of the flicker-noise temporal correlation spectrum of the liposomes leads to τ ~/= 0.5 s, comparing favorably with an intrinsic reaction-cycle time of about 0.4 s from enzymology.
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