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Biswas B, Shah D, Cox-Vázquez SJ, Vázquez RJ. Sensing cholesterol-induced rigidity in model membranes with time-resolved fluorescence spectroscopy and microscopy. J Mater Chem B 2024; 12:6570-6576. [PMID: 38899544 DOI: 10.1039/d4tb00872c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Here, we report the characterization of cholesterol levels on membrane fluidity with a twisted intramolecular charge transfer (TICT) membrane dye, namely DI-8-ANEPPS, using fluorescence lifetime techniques such as time-correlated single photon counting (TCSPC) and fluorescence lifetime imaging microscopy (FLIM). The characterized liposomes comprised a 3 : 1 ratio of POPC and POPG, respectively, 1% DI-8-ANEPPS, and increasing cholesterol levels from 0% to 50%. Fluorescence lifetime characterization revealed that increasing the cholesterol levels from 0% to 50% increases the fluorescence lifetime of DI-8-ANEPPS from 2.36 ns to 3.65 ns, a 55% increment. Such lengthening in the fluorescence lifetime is concomitant with reduced Stokes shifts and higher quantum yield, revealing that localized excitation (LE) dominates over TICT states with increased cholesterol levels. Fluorescence anisotropy measurements revealed a less isotropic environment in the membrane upon increasing cholesterol levels, suggesting a shift from liquid-disorder (Lα) to liquid-order (LO) upon adding cholesterol. Local electrostatic and dipole characterization experiments revealed that changes in the zeta-potential (ζ-potential) and transmembrane dipole potential (Ψd) induced by changes in cholesterol levels or the POPC : POPG ratio play a minimal role in the fluorescence lifetime outcome of DI-8-ANEPPS. Instead, these results indicate that the cholesterol's effect in restricting the degree of movement of DI-8-ANEPPS dominates its photophysics over the cholesterol effect on the local dipole strength. We envision that time-resolved spectroscopy and microscopy, coupled with TICT dyes, could be a convenient tool in exploring the complex interplay between membrane lipids, sterols, and proteins and provide novel insights into membrane fluidity, organization, and function.
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Affiliation(s)
- Bidisha Biswas
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA.
| | - Dhari Shah
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA.
| | - Sarah J Cox-Vázquez
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA.
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2
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Szomek M, Akkerman V, Lauritsen L, Walther HL, Juhl AD, Thaysen K, Egebjerg JM, Covey DF, Lehmann M, Wessig P, Foster AJ, Poolman B, Werner S, Schneider G, Müller P, Wüstner D. Ergosterol promotes aggregation of natamycin in the yeast plasma membrane. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184350. [PMID: 38806103 DOI: 10.1016/j.bbamem.2024.184350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 05/11/2024] [Accepted: 05/24/2024] [Indexed: 05/30/2024]
Abstract
Polyene macrolides are antifungal substances, which interact with cells in a sterol-dependent manner. While being widely used, their mode of action is poorly understood. Here, we employ ultraviolet-sensitive (UV) microscopy to show that the antifungal polyene natamycin binds to the yeast plasma membrane (PM) and causes permeation of propidium iodide into cells. Right before membrane permeability became compromised, we observed clustering of natamycin in the PM that was independent of PM protein domains. Aggregation of natamycin was paralleled by cell deformation and membrane blebbing as revealed by soft X-ray microscopy. Substituting ergosterol for cholesterol decreased natamycin binding and caused a reduced clustering of natamycin in the PM. Blocking of ergosterol synthesis necessitates sterol import via the ABC transporters Aus1/Pdr11 to ensure natamycin binding. Quantitative imaging of dehydroergosterol (DHE) and cholestatrienol (CTL), two analogues of ergosterol and cholesterol, respectively, revealed a largely homogeneous lateral sterol distribution in the PM, ruling out that natamycin binds to pre-assembled sterol domains. Depletion of sphingolipids using myriocin increased natamycin binding to yeast cells, likely by increasing the ergosterol fraction in the outer PM leaflet. Importantly, binding and membrane aggregation of natamycin was paralleled by a decrease of the dipole potential in the PM, and this effect was enhanced in the presence of myriocin. We conclude that ergosterol promotes binding and aggregation of natamycin in the yeast PM, which can be synergistically enhanced by inhibitors of sphingolipid synthesis.
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Affiliation(s)
- Maria Szomek
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Vibeke Akkerman
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Line Lauritsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Hanna-Loisa Walther
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Alice Dupont Juhl
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Katja Thaysen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Jacob Marcus Egebjerg
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Douglas F Covey
- Department of Developmental Biology, Washington University in St. Louis, St. Louis, MO 63110, USA; Taylor Family Institute for Innovative Psychiatric Research, USA
| | - Max Lehmann
- Institute for Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, D-14476 Potsdam, Germany
| | - Pablo Wessig
- Institute for Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, D-14476 Potsdam, Germany
| | - Alexander J Foster
- Department of Biochemistry, University of Groningen, Nijenborgh 4, 9747 Groningen, the Netherlands
| | - Bert Poolman
- Department of Biochemistry, University of Groningen, Nijenborgh 4, 9747 Groningen, the Netherlands
| | - Stephan Werner
- Department of X-Ray Microscopy, Helmholtz-Zentrum Berlin, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - Gerd Schneider
- Department of X-Ray Microscopy, Helmholtz-Zentrum Berlin, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - Peter Müller
- Department of Biology, Humboldt University Berlin, Invalidenstr. 43, D-10115 Berlin, Germany
| | - Daniel Wüstner
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.
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3
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Youngworth R, Roux B. Simulating the Voltage-Dependent Fluorescence of Di-8-ANEPPS in a Lipid Membrane. J Phys Chem Lett 2023; 14:8268-8276. [PMID: 37676243 PMCID: PMC10510438 DOI: 10.1021/acs.jpclett.3c01257] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 08/25/2023] [Indexed: 09/08/2023]
Abstract
Voltage-sensitive fluorescent dyes such as di-8-ANEPPS (di-8-aminonaphthylethylenepyridinium propylsulfonate) are powerful tools to study biological membranes. Its fluorescence is affected by changes in the membrane potential and other factors, requiring extensive calibration to extract meaningful quantitative results. The amphiphilic di-8-ANEPPS molecule is expected to bind at the membrane-solution interface. However, atomic-level information is sparse about its position and orientation in the membrane, especially in regards to how the latter dynamically fluctuates to affect the observed fluorescence. In the present work, molecular dynamics simulations of the ground and excited states of di-8-ANEPPS embedded in a DPPC membrane as represented by classical force fields were used to investigate how the fluorescence is affected by externally applied potential. The calculations reproduce the shifts in the wavelength of emission as a function of voltage that are observed experimentally, indicating that the approach can help better understand the various factors that can affect the fluorescence of membrane-bound dyes.
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Affiliation(s)
- Rachael Youngworth
- Department
of Chemistry, The University of Chicago, 5735 S. Ellis Avenue, Chicago, Illinois 60637, United States
| | - Benoît Roux
- Department
of Biochemistry and Molecular Biology, The
University of Chicago, 929 E. 57th Street W225, Chicago, Illinois 60637, United States
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4
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Sarkar P, Chattopadhyay A. Membrane Dipole Potential: An Emerging Approach to Explore Membrane Organization and Function. J Phys Chem B 2022; 126:4415-4430. [PMID: 35696090 DOI: 10.1021/acs.jpcb.2c02476] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Biological membranes are complex organized molecular assemblies of lipids and proteins that provide cells and membrane-bound intracellular organelles their individual identities by morphological compartmentalization. Membrane dipole potential originates from the electrostatic potential difference within the membrane due to the nonrandom arrangement (orientation) of amphiphile and solvent (water) dipoles at the membrane interface. In this Feature Article, we will focus on the measurement of dipole potential using electrochromic fluorescent probes and highlight interesting applications. In addition, we will focus on ratiometric fluorescence microscopic imaging technique to measure dipole potential in cellular membranes, a technique that can be used to address novel problems in cell biology which are otherwise difficult to address using available approaches. We envision that membrane dipole potential could turn out to be a convenient tool in exploring the complex interplay between membrane lipids and proteins and could provide novel insights in membrane organization and function.
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Affiliation(s)
- Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
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5
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Barbosa JC, Gonçalves S, Makowski M, Silva ÍC, Caetano T, Schneider T, Mösker E, Süssmuth RD, Santos NC, Mendo S. Insights into the mode of action of the two-peptide lantibiotic lichenicidin. Colloids Surf B Biointerfaces 2022; 211:112308. [PMID: 34973602 DOI: 10.1016/j.colsurfb.2021.112308] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 12/22/2021] [Accepted: 12/23/2021] [Indexed: 11/30/2022]
Abstract
Lantibiotics are promising candidates to address the worldwide problem of antibiotic resistance. They belong to a class of natural compounds exhibiting strong activity against clinically relevant Gram-positive bacterial strains, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE). Lichenicidin is a class II two-peptide lantibiotic. The presence of the two mature peptides, Bliα and Bliβ, is necessary for full activity against target bacteria. This work aims at clarifying the synergistic activity of both peptides in their interaction with the target membranes. The effect of lichenicidin was tested against S. aureus cells and large unilamellar vesicles. Lichenicidin increases the net surface charge of S. aureus, as shown by zeta-potential measurements, without reaching electroneutralization. In addition, lichenicidin causes cell surface perturbations that culminate in the leakage of its internal contents, as observed by atomic force microscopy. Bliα seems to have low affinity for S. aureus, however, it contributes to increase the affinity of Bliβ, because together they present higher affinity than separately. In contrast, Bliα seems to provide an anchoring site for lichenicidin in lipid II-containing membranes. Interestingly, Bliβ alone can induce high levels of membrane leakage, but this effect appears to be faster in the presence of Bliα. Based on this information, we propose a mechanism of action of lichenicidin.
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Affiliation(s)
- Joana C Barbosa
- Department of Biology & Centre for Environmental and Marine Studies (CESAM), University of Aveiro, Aveiro, Portugal.
| | - Sónia Gonçalves
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, Lisbon, Portugal.
| | - Marcin Makowski
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, Lisbon, Portugal.
| | - Ítala C Silva
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, Lisbon, Portugal.
| | - Tânia Caetano
- Department of Biology & Centre for Environmental and Marine Studies (CESAM), University of Aveiro, Aveiro, Portugal.
| | - Tanja Schneider
- Institute for Pharmaceutical Microbiology, University of Bonn, Bonn, Germany.
| | - Eva Mösker
- Institut für Chemie, Technische Universität Berlin, Berlin, Germany.
| | | | - Nuno C Santos
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, Lisbon, Portugal.
| | - Sónia Mendo
- Department of Biology & Centre for Environmental and Marine Studies (CESAM), University of Aveiro, Aveiro, Portugal.
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6
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It Takes More than Two to Tango: Complex, Hierarchal, and Membrane-Modulated Interactions in the Regulation of Receptor Tyrosine Kinases. Cancers (Basel) 2022; 14:cancers14040944. [PMID: 35205690 PMCID: PMC8869822 DOI: 10.3390/cancers14040944] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 02/09/2022] [Accepted: 02/12/2022] [Indexed: 12/18/2022] Open
Abstract
The search for an understanding of how cell fate and motility are regulated is not a purely scientific undertaking, but it can also lead to rationally designed therapies against cancer. The discovery of tyrosine kinases about half a century ago, the subsequent characterization of certain transmembrane receptors harboring tyrosine kinase activity, and their connection to the development of human cancer ushered in a new age with the hope of finding a treatment for malignant diseases in the foreseeable future. However, painstaking efforts were required to uncover the principles of how these receptors with intrinsic tyrosine kinase activity are regulated. Developments in molecular and structural biology and biophysical approaches paved the way towards better understanding of these pathways. Discoveries in the past twenty years first resulted in the formulation of textbook dogmas, such as dimerization-driven receptor association, which were followed by fine-tuning the model. In this review, the role of molecular interactions taking place during the activation of receptor tyrosine kinases, with special attention to the epidermal growth factor receptor family, will be discussed. The fact that these receptors are anchored in the membrane provides ample opportunities for modulatory lipid-protein interactions that will be considered in detail in the second part of the manuscript. Although qualitative and quantitative alterations in lipids in cancer are not sufficient in their own right to drive the malignant transformation, they both contribute to tumor formation and also provide ways to treat cancer. The review will be concluded with a summary of these medical aspects of lipid-protein interactions.
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7
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Andronico LA, Jiang Y, Jung SR, Fujimoto BS, Vojtech L, Chiu DT. Sizing Extracellular Vesicles Using Membrane Dyes and a Single Molecule-Sensitive Flow Analyzer. Anal Chem 2021; 93:5897-5905. [PMID: 33784071 DOI: 10.1021/acs.analchem.1c00253] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Extracellular vesicles (EVs) are membranous particles released by most cells in our body, which are involved in many cell-to-cell signaling processes. Given the nanometer sizes and heterogeneity of EVs, highly sensitive methods with single-molecule resolution are fundamental to investigating their biophysical properties. Here, we demonstrate the sizing of EVs using a fluorescence-based flow analyzer with single-molecule sensitivity. Using a dye that selectively partitions into the vesicle's membrane, we show that the fluorescence intensity of a vesicle is proportional to its diameter. We discuss the constraints in sample preparation which are inherent to sizing nanoscale vesicles with a fluorescent membrane dye and propose several guidelines to improve data consistency. After optimizing staining conditions, we were able to measure the size of vesicles in the range ∼35-300 nm, covering the spectrum of EV sizes. Lastly, we developed a method to correct the signal intensity from each vesicle based on its traveling speed inside the microfluidic channel, by operating at a high sampling rate (10 kHz) and measuring the time required for the particle to cross the laser beam. Using this correction, we obtained a threefold greater accuracy in EV sizing, with a precision of ±15-25%.
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Affiliation(s)
- Luca A Andronico
- Department of Chemistry, University of Washington, Seattle 98195, Washington, United States
| | - Yifei Jiang
- Department of Chemistry, University of Washington, Seattle 98195, Washington, United States
| | - Seung-Ryoung Jung
- Department of Chemistry, University of Washington, Seattle 98195, Washington, United States
| | - Bryant S Fujimoto
- Department of Chemistry, University of Washington, Seattle 98195, Washington, United States
| | - Lucia Vojtech
- Department of Obstetrics and Gynecology, University of Washington, Seattle 98195, Washington, United States
| | - Daniel T Chiu
- Department of Chemistry, University of Washington, Seattle 98195, Washington, United States
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8
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Zakany F, Szabo M, Batta G, Kárpáti L, Mándity IM, Fülöp P, Varga Z, Panyi G, Nagy P, Kovacs T. An ω-3, but Not an ω-6 Polyunsaturated Fatty Acid Decreases Membrane Dipole Potential and Stimulates Endo-Lysosomal Escape of Penetratin. Front Cell Dev Biol 2021; 9:647300. [PMID: 33912562 PMCID: PMC8074792 DOI: 10.3389/fcell.2021.647300] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 03/22/2021] [Indexed: 12/21/2022] Open
Abstract
Although the largely positive intramembrane dipole potential (DP) may substantially influence the function of transmembrane proteins, its investigation is deeply hampered by the lack of measurement techniques suitable for high-throughput examination of living cells. Here, we describe a novel emission ratiometric flow cytometry method based on F66, a 3-hydroxiflavon derivative, and demonstrate that 6-ketocholestanol, cholesterol and 7-dehydrocholesterol, saturated stearic acid (SA) and ω-6 γ-linolenic acid (GLA) increase, while ω-3 α-linolenic acid (ALA) decreases the DP. These changes do not correlate with alterations in cell viability or membrane fluidity. Pretreatment with ALA counteracts, while SA or GLA enhances cholesterol-induced DP elevations. Furthermore, ALA (but not SA or GLA) increases endo-lysosomal escape of penetratin, a cell-penetrating peptide. In summary, we have developed a novel method to measure DP in large quantities of individual living cells and propose ALA as a physiological DP lowering agent facilitating cytoplasmic entry of penetratin.
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Affiliation(s)
- Florina Zakany
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Mate Szabo
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Gyula Batta
- Department of Genetics and Applied Microbiology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - Levente Kárpáti
- Department of Organic Chemistry, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary
| | - István M. Mándity
- Department of Organic Chemistry, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary
- Lendület-Artificial Chloride Ion Transporter Group, Institute of Materials and Environmental Chemistry, Research Center for Natural Sciences, Budapest, Hungary
| | - Péter Fülöp
- Division of Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Zoltan Varga
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Gyorgy Panyi
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Peter Nagy
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Tamas Kovacs
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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9
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Fabiunke S, Fillafer C, Paeger A, Schneider MF. Optical studies of membrane state during action potential propagation. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 162:69-78. [DOI: 10.1016/j.pbiomolbio.2020.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 10/05/2020] [Accepted: 11/13/2020] [Indexed: 10/23/2022]
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10
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Affiliation(s)
- Nadav Amdursky
- Schulich Faculty of ChemistryTechnion – Israel Institute of Technology Haifa 3200003 Israel
| | - Yiyang Lin
- State Key Laboratory of Organic-Inorganic Composites Beijing Laboratory of Biomedical MaterialsBeijing University of Chemical Technology Beijing 100029 China
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11
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Feruglio PF, Vinegoni C, Weissleder R. Extended dynamic range imaging for noise mitigation in fluorescence anisotropy imaging. JOURNAL OF BIOMEDICAL OPTICS 2020; 25:JBO-200159R. [PMID: 32820624 PMCID: PMC7439791 DOI: 10.1117/1.jbo.25.8.086003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 07/27/2020] [Indexed: 06/11/2023]
Abstract
SIGNIFICANCE Fluorescence polarization (FP) and fluorescence anisotropy (FA) microscopy are powerful imaging techniques that allow to translate the common FP assay capabilities into the in vitro and in vivo cellular domain. As a result, they have found potential for mapping drug-protein or protein-protein interactions. Unfortunately, these imaging modalities are ratiometric in nature and as such they suffer from excessive noise even under regular imaging conditions, preventing accurate image-feature analysis of fluorescent molecules behaviors. AIM We present a high dynamic range (HDR)-based FA imaging modality for improving image quality in FA microscopy. APPROACH The method exploits ad hoc acquisition schemes to extend the dynamic range of individual FP channels, allowing to obtain FA images with increased signal-to-noise ratio. RESULTS A direct comparison between FA images obtained with our method and the standard, clearly indicates how an HDR-based FA imaging approach allows to obtain high-quality images, with the ability to correctly resolve image features at different values of FA and over a substantially higher range of fluorescence intensities. CONCLUSION The method presented is shown to outperform standard FA imaging microscopy narrowing the spread of the propagated error and yielding higher quality images. The method can be effectively and routinely used on any commercial imaging system and could be also translated to other microscopy ratiometric imaging modalities.
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Affiliation(s)
- Paolo Fumene Feruglio
- Massachusetts General Hospital, Harvard Medical School, Center for Systems Biology, Boston, Massachusetts, United States
- University of Verona, Department of Neuroscience, Biomedicine, and Movement Sciences, Verona, Italy
- ITS Meccatronico Veneto, Vicenza, Italy
| | - Claudio Vinegoni
- Massachusetts General Hospital, Harvard Medical School, Center for Systems Biology, Boston, Massachusetts, United States
| | - Ralph Weissleder
- Massachusetts General Hospital, Harvard Medical School, Center for Systems Biology, Boston, Massachusetts, United States
- Harvard Medical School, Department of Systems Biology, Boston, Massachusetts, United States
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12
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Sensing Senses: Optical Biosensors to Study Gustation. SENSORS 2020; 20:s20071811. [PMID: 32218129 PMCID: PMC7180777 DOI: 10.3390/s20071811] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 03/19/2020] [Accepted: 03/21/2020] [Indexed: 12/11/2022]
Abstract
The five basic taste modalities, sweet, bitter, umami, salty and sour induce changes of Ca2+ levels, pH and/or membrane potential in taste cells of the tongue and/or in neurons that convey and decode gustatory signals to the brain. Optical biosensors, which can be either synthetic dyes or genetically encoded proteins whose fluorescence spectra depend on levels of Ca2+, pH or membrane potential, have been used in primary cells/tissues or in recombinant systems to study taste-related intra- and intercellular signaling mechanisms or to discover new ligands. Taste-evoked responses were measured by microscopy achieving high spatial and temporal resolution, while plate readers were employed for higher throughput screening. Here, these approaches making use of fluorescent optical biosensors to investigate specific taste-related questions or to screen new agonists/antagonists for the different taste modalities were reviewed systematically. Furthermore, in the context of recent developments in genetically encoded sensors, 3D cultures and imaging technologies, we propose new feasible approaches for studying taste physiology and for compound screening.
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13
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Henriques ST, Peacock H, Benfield AH, Wang CK, Craik DJ. Is the Mirror Image a True Reflection? Intrinsic Membrane Chirality Modulates Peptide Binding. J Am Chem Soc 2019; 141:20460-20469. [PMID: 31765148 DOI: 10.1021/jacs.9b11194] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Peptides with pharmaceutical activities are attractive drug leads, and knowledge of their mode-of-action is essential for translation into the clinic. Comparison of native and enantiomeric peptides has long been used as a powerful approach to discriminate membrane- or receptor-mediated modes-of-action on the basis of the assumption that interactions with cell membranes are independent of peptide chirality. Here, we revisit this paradigm with the cyclotide kalata B1, a drug scaffold with intrinsic membrane-binding activity whose enantiomer is less potent than native peptide. To investigate this chirality dependence, we compared peptide-lipid binding using mirror image model membranes. We synthesized phospholipids with non-natural chirality and demonstrate that native kalata B1 binds with higher affinity to phospholipids with chirality found in eukaryotic membranes. This study shows for the first time that the chiral environment of lipid bilayers can modulate the function of membrane-active peptides and challenges the view that peptide-lipid interactions are achiral.
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Affiliation(s)
- Sónia Troeira Henriques
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , Queensland 4072 , Australia.,School of Biomedical Sciences, Faculty of Health, Institute of Health & Biomedical Innovation , Queensland University of Technology , Translational Research Institute , Brisbane , Queensland 4102 , Australia
| | - Hayden Peacock
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , Queensland 4072 , Australia
| | - Aurélie H Benfield
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , Queensland 4072 , Australia.,School of Biomedical Sciences, Faculty of Health, Institute of Health & Biomedical Innovation , Queensland University of Technology , Translational Research Institute , Brisbane , Queensland 4102 , Australia
| | - Conan K Wang
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , Queensland 4072 , Australia
| | - David J Craik
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , Queensland 4072 , Australia
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14
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Noh HW, Ahn CG, Kong HJ, Sim JY. Ratiometric Impedance Sensing of Fingers for Robust Identity Authentication. Sci Rep 2019; 9:13566. [PMID: 31537843 PMCID: PMC6753141 DOI: 10.1038/s41598-019-49792-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 08/27/2019] [Indexed: 01/30/2023] Open
Abstract
We present a novel biometric authentication system enabled by ratiometric analysis of impedance of fingers. In comparison to the traditional biometrics that relies on acquired images of structural information of physiological characteristics, our biological impedance approach not only eliminates any practical means of making fake copies of the relevant physiological traits but also provides reliable features of biometrics using the ratiometric impedance of fingers. This study shows that the ratiometric features of the impedance of fingers in 10 different pairs using 5 electrodes at the fingertips can reduce the variation due to undesirable factors such as temperature and day-to-day physiological variations. By calculating the ratio of impedances, the difference between individual subjects was amplified and the spectral patterns were diversified. Overall, our ratiometric analysis of impedance improved the classification accuracy of 41 subjects and reduced the error rate of classification from 29.32% to 5.86% (by a factor of 5).
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Affiliation(s)
- Hyung Wook Noh
- Medical Information Research Section, Welfare & Medical ICT Research Department, Electronics and Telecommunications Research Institute, Daejeon, 34129, Republic of Korea
- Department of Biomedical Engineering, Chungnam National University College of Medicine, 266 Munwha-ro, Jung-gu, Daejeon, 35015, Republic of Korea
| | - Chang-Geun Ahn
- Medical Information Research Section, Welfare & Medical ICT Research Department, Electronics and Telecommunications Research Institute, Daejeon, 34129, Republic of Korea
| | - Hyoun-Joong Kong
- Department of Biomedical Engineering, Chungnam National University College of Medicine, 266 Munwha-ro, Jung-gu, Daejeon, 35015, Republic of Korea
| | - Joo Yong Sim
- Medical Information Research Section, Welfare & Medical ICT Research Department, Electronics and Telecommunications Research Institute, Daejeon, 34129, Republic of Korea.
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15
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Ortiz A, Girona V, Prat J, Muñoz-Juncosa MM, Alsina MA, Pujol M. Interaction of the GBV-C E2-derived peptide, P6-2VIR576, with anionic phospholipid membranes. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2017.04.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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16
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Saliba D, Al-Ghoul M. Kinetics of intercalation of fluorescent probes in magnesium-aluminium layered double hydroxide within a multiscale reaction-diffusion framework. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2016; 374:rsta.2016.0138. [PMID: 27698034 PMCID: PMC5052724 DOI: 10.1098/rsta.2016.0138] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/01/2016] [Indexed: 05/27/2023]
Abstract
We report the synthesis of magnesium-aluminium layered double hydroxide (LDH) using a reaction-diffusion framework (RDF) that exploits the multiscale coupling of molecular diffusion with chemical reactions, nucleation and growth of crystals. In an RDF, the hydroxide anions are allowed to diffuse into an organic gel matrix containing the salt mixture needed for the precipitation of the LDH. The chemical structure and composition of the synthesized magnesium-aluminium LDHs are determined using powder X-ray diffraction (PXRD), thermo-gravimetric analysis, differential scanning calorimetry, solid-state nuclear magnetic resonance (SSNMR), Fourier transform infrared and energy dispersive X-ray spectroscopy. This novel technique also allows the investigation of the mechanism of intercalation of some fluorescent probes, such as the neutral three-dimensional rhodamine B (RhB) and the negatively charged two-dimensional 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS), using in situ steady-state fluorescence spectroscopy. The incorporation of these organic dyes inside the interlayer region of the LDH is confirmed via fluorescence microscopy, solid-state lifetime, SSNMR and PXRD. The activation energies of intercalation of the corresponding molecules (RhB and HPTS) are computed and exhibit dependence on the geometry of the involved probe (two or three dimensions), the charge of the fluorescent molecule (anionic, cationic or neutral) and the cationic ratio of the corresponding LDH.This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'.
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Affiliation(s)
- Daniel Saliba
- Department of Chemistry, American University of Beirut, PO Box 11-0236, Riad El-Solh 1107 2020, Beirut, Lebanon
| | - Mazen Al-Ghoul
- Department of Chemistry, American University of Beirut, PO Box 11-0236, Riad El-Solh 1107 2020, Beirut, Lebanon
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17
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Santos FC, Fernandes AS, Antunes CAC, Moreira FP, Videira A, Marinho HS, de Almeida RFM. Reorganization of plasma membrane lipid domains during conidial germination. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:156-166. [PMID: 27815222 DOI: 10.1016/j.bbalip.2016.10.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 10/10/2016] [Accepted: 10/28/2016] [Indexed: 01/12/2023]
Abstract
Neurospora crassa, a filamentous fungus, in the unicellular conidial stage has ideal features to study sphingolipid (SL)-enriched domains, which are implicated in fundamental cellular processes ranging from antifungal resistance to apoptosis. Several changes in lipid metabolism and in the membrane composition of N. crassa occur during spore germination. However, the biophysical impact of those changes is unknown. Thus, a biophysical study of N. crassa plasma membrane, particularly SL-enriched domains, and their dynamics along conidial germination is prompted. Two N. crassa strains, wild-type (WT) and slime, which is devoid of cell wall, were studied. Conidial growth of N. crassa WT from a dormancy state to an exponential phase was accompanied by membrane reorganization, namely an increase of membrane fluidity, occurring faster in a supplemented medium than in Vogel's minimal medium. Gel-like domains, likely enriched in SLs, were found in both N. crassa strains, but were particularly compact, rigid and abundant in the case of slime cells, even more than in budding yeast Saccharomyces cerevisiae. In N. crassa, our results suggest that the melting of SL-enriched domains occurs near growth temperature (30°C) for WT, but at higher temperatures for slime. Regarding biophysical properties strongly affected by ergosterol, the plasma membrane of slime conidia lays in between those of N. crassa WT and S. cerevisiae cells. The differences in biophysical properties found in this work, and the relationships established between membrane lipid composition and dynamics, give new insights about the plasma membrane organization and structure of N. crassa strains during conidial growth.
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Affiliation(s)
- Filipa C Santos
- Centro de Química e Bioquímica, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - Andreia S Fernandes
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal; Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
| | - Catarina A C Antunes
- Centro de Química e Bioquímica, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - Filipe P Moreira
- Centro de Química e Bioquímica, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - Arnaldo Videira
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal; Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; ICBAS-Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal
| | - H Susana Marinho
- Centro de Química e Bioquímica, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - Rodrigo F M de Almeida
- Centro de Química e Bioquímica, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal.
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18
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Demchenko AP, Duportail G, Oncul S, Klymchenko AS, Mély Y. Introduction to fluorescence probing of biological membranes. Methods Mol Biol 2015; 1232:19-43. [PMID: 25331125 DOI: 10.1007/978-1-4939-1752-5_3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Fluorescence is one of the most powerful and commonly used tools in biophysical studies of biomembrane structure and dynamics that can be applied on different levels, from lipid monolayers and bilayers to living cells, tissues, and whole animals. Successful application of this method relies on proper design of fluorescence probes with optimized photophysical properties. These probes are efficient for studying the microscopic analogs of viscosity, polarity, and hydration, as well as the molecular order, environment relaxation, and electrostatic potentials at the sites of their location. Being smaller than the membrane width they can sense the gradients of these parameters across the membrane. We present examples of novel dyes that achieve increased spatial resolution and information content of the probe responses. In this respect, multiparametric environment-sensitive probes feature considerable promise.
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Affiliation(s)
- Alexander P Demchenko
- Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, 9 Leontovicha Street, Kiev, 01030, Ukraine,
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19
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Marquês JT, Antunes CA, Santos FC, de Almeida RF. Biomembrane Organization and Function. ADVANCES IN PLANAR LIPID BILAYERS AND LIPOSOMES 2015. [DOI: 10.1016/bs.adplan.2015.06.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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20
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Ben-Dov N, Korenstein R. The uptake of HIV Tat peptide proceeds via two pathways which differ from macropinocytosis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1848:869-77. [PMID: 25542781 DOI: 10.1016/j.bbamem.2014.12.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 11/16/2014] [Accepted: 12/16/2014] [Indexed: 12/20/2022]
Abstract
Cell penetrating peptides (CPPs) have been extensively studied as vectors for cellular delivery of therapeutic molecules, yet the identity of their uptake routes remained unclear and is still under debate. In this study we provide new insights into CPP entry routes by quantitatively measuring the intracellular uptake of FAM-labeled Tat-peptide under rigorous kinetic and thermal conditions. The uptake of Tat-peptide between 4 and 15°C corresponds to Q10=1.1, proceeding through a prompt (<5 min), temperature-independent process, suggesting direct membrane translocation. At longer durations, Tat rate of uptake shows linear dependence on temperature with Q10=1.44, accompanied by activation energy Ea=4.45 Kcal/mole. These values are significantly lower than those we found for the macropinocytosis probe dextran (Q10=2.2 and Ea=7.2 Kcal/mole) which possesses an exponential dependence on temperature, characteristic of endocytosis processes. Tat-peptide and dextran do not interfere with each other's uptake rate and the ratio of Tat-peptide uptake to its extracellular concentration is ~15 times higher than that for dextran. In addition, Phloretin, a modulator of cell membrane dipole potential, is shown to increase dextran uptake but to reduce that of Tat. We conclude that the uptake of Tat differs from that of dextran in all parameters. Tat uptake proceeds by dual entry routes which differ by their energy dependence.
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Affiliation(s)
- Nadav Ben-Dov
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel-Aviv University, 69978 Tel-Aviv, Israel.
| | - Rafi Korenstein
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel-Aviv University, 69978 Tel-Aviv, Israel.
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21
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22
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Figueira TN, Veiga AS, Castanho MA. The interaction of antibodies with lipid membranes unraveled by fluorescence methodologies. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2014.02.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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23
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The alteration of lipid bilayer dynamics by phloretin and 6-ketocholestanol. Chem Phys Lipids 2013; 178:38-44. [PMID: 24316311 DOI: 10.1016/j.chemphyslip.2013.11.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 11/13/2013] [Accepted: 11/14/2013] [Indexed: 02/06/2023]
Abstract
Lipid bilayer properties are quantified with a variety of arbitrary selected parameters such as molecular packing and dynamics, electrostatic potentials or permeability. In the paper we determined the effect of phloretin and 6-ketocholestanol (dipole potential modifying agents) on the membrane hydration and efficiency of the trans-membrane water flow. The dynamics of water molecules within the lipid bilayer interface was evaluated using solvent relaxation method, whereas the osmotically induced trans-membrane water flux was estimated with the stopped-flow method using the liposome shrinkage kinetics. The presence of phloretin or 6-ketocholestanol resulted in a change of both, the interfacial hydration level and osmotically driven water fluxes. Specifically, the presence of 6-ketocholestanol reduced the amount and mobility of water in the membrane interface. It also slows the osmotically induced water flow. The interfacial hydration change caused by phloretin was much smaller and the effect on osmotically induced water flow was opposite to that of 6-ketocholestanol.
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24
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Manno C, Figueroa L, Fitts R, Ríos E. Confocal imaging of transmembrane voltage by SEER of di-8-ANEPPS. ACTA ACUST UNITED AC 2013; 141:371-87. [PMID: 23440278 PMCID: PMC3581694 DOI: 10.1085/jgp.201210936] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Imaging, optical mapping, and optical multisite recording of transmembrane potential (Vm) are essential for studying excitable cells and systems. The naphthylstyryl voltage-sensitive dyes, including di-8-ANEPPS, shift both their fluorescence excitation and emission spectra upon changes in Vm. Accordingly, they have been used for monitoring Vm in nonratioing and both emission and excitation ratioing modes. Their changes in fluorescence are usually much less than 10% per 100 mV. Conventional ratioing increases sensitivity to between 3 and 15% per 100 mV. Low sensitivity limits the value of these dyes, especially when imaged with low light systems like confocal scanners. Here we demonstrate the improvement afforded by shifted excitation and emission ratioing (SEER) as applied to imaging membrane potential in flexor digitorum brevis muscle fibers of adult mice. SEER—the ratioing of two images of fluorescence, obtained with different excitation wavelengths in different emission bands—was implemented in two commercial confocal systems. A conventional pinhole scanner, affording optimal setting of emission bands but less than ideal excitation wavelengths, achieved a sensitivity of up to 27% per 100 mV, nearly doubling the value found by conventional ratioing of the same data. A better pair of excitation lights should increase the sensitivity further, to 35% per 100 mV. The maximum acquisition rate with this system was 1 kHz. A fast “slit scanner” increased the effective rate to 8 kHz, but sensitivity was lower. In its high-sensitivity implementation, the technique demonstrated progressive deterioration of action potentials upon fatiguing tetani induced by stimulation patterns at >40 Hz, thereby identifying action potential decay as a contributor to fatigue onset. Using the fast implementation, we could image for the first time an action potential simultaneously at multiple locations along the t-tubule system. These images resolved the radially varying lag associated with propagation at a finite velocity.
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Affiliation(s)
- Carlo Manno
- Section of Cellular Signaling, Department of Molecular Biophysics and Physiology, Rush University, Chicago, IL 60612, USA
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25
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Decoding distinct membrane interactions of HIV-1 fusion inhibitors using a combined atomic force and fluorescence microscopy approach. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:1777-85. [DOI: 10.1016/j.bbamem.2013.03.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 01/01/2013] [Accepted: 03/03/2013] [Indexed: 11/19/2022]
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26
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Ben-Dov N, Korenstein R. Proton-induced endocytosis is dependent on cell membrane fluidity, lipid-phase order and the membrane resting potential. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2672-81. [PMID: 23911577 DOI: 10.1016/j.bbamem.2013.07.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 07/20/2013] [Accepted: 07/22/2013] [Indexed: 01/13/2023]
Abstract
Recently it has been shown that decreasing the extracellular pH of cells stimulates the formation of inward membrane invaginations and vesicles, accompanied by an enhanced uptake of macromolecules. This type of endocytosis was coined as proton-induced uptake (PIU). Though the initial induction of inward membrane curvature was rationalized in terms of proton-based increase of charge asymmetry across the membrane, the dependence of the phenomenon on plasma membrane characteristics is still unknown. The present study shows that depolarization of the membrane resting potential elevates PIU by 25%, while hyperpolarization attenuates it by 25%. Comparison of uptake in suspended and adherent cells implicates that the resting-potential affects PIU through remodeling the actin-cytoskeleton. The pH at the external interface of the cell membrane rather than the pH gradient across it determines the extent of PIU. PIU increases linearly upon temperature increase in the range of 4-36°C, in correlation with the membrane fluidity. The plasma membrane fluidity and the lipid phase order are modulated by enriching the cell's membrane with cholesterol, tergitol, dimethylsulfoxide, 6-ketocholestanol and phloretin and by cholesterol depletion. These treatments are shown to alter the extent of PIU and are better correlated with membrane fluidity than with the lipid phase order. We suggest that the lipid phase order and fluidity influence PIU by regulating the lipid order gradient across the perimeter of the lipid-condensed microdomains (rafts) and alter the characteristic tension line that separates the higher ordered lipid-domains from the lesser ordered ones.
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Affiliation(s)
- Nadav Ben-Dov
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel-Aviv University, 69978 Tel-Aviv, Israel.
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27
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Abstract
There are three kinds of membrane potentials: the surface potentials, resulting from the accumulation of charges at the membrane surfaces; the transmembrane potential, determined by imbalance of charge in the aqueous solutions; and the dipole potential, a membrane-internal potential from the dipolar components of the phospholipids and interface water. The absolute value of the dipole potential has been very difficult to measure, although its value has been estimated to be in the range of 200-1,000 mV from ion translocation rates (determined by the planar lipid bilayer method), the surface potential of lipid monolayers (determined by the lipid monolayer method), molecular-dynamics calculations, and electron scattering using cryoelectron microscopy (cryo-EM). Spectroscopy methods have also been used to monitor the dipole potential changes on the basis of the observed fluorescence changes of voltage-sensitive probes. The dipole potential accounts for the much larger permeability of a bare phospholipid membrane to anions than cations and affects the conformation and function of membrane proteins.
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Affiliation(s)
- Liguo Wang
- Department of Biological Structure, University of Washington, Seattle, Washington 98195, USA.
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28
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Klymchenko AS, Duportail G, Mély Y. 3-Hydroxychromone Probes Precisely Located and Oriented in Lipid Bilayers: A Toolkit for Biomembrane Research. SPRINGER SERIES ON FLUORESCENCE 2012. [DOI: 10.1007/4243_2012_44] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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29
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Bachtel AD, Gray RA, Stohlman JM, Bourgeois EB, Pollard AE, Rogers JM. A novel approach to dual excitation ratiometric optical mapping of cardiac action potentials with di-4-ANEPPS using pulsed LED excitation. IEEE Trans Biomed Eng 2011; 58:2120-6. [PMID: 21536528 DOI: 10.1109/tbme.2011.2148719] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We developed a new method for ratiometric optical mapping of transmembrane potential (V(m)) in cardiac preparations stained with di-4-ANEPPS. V(m)-dependent shifts of excitation and emission spectra establish two excitation bands (<481 and >481 nm) that produce fluorescence changes of opposite polarity within a single emission band (575-620 nm). The ratio of these positive and negative fluorescence signals (excitation ratiometry) increases V(m) sensitivity and removes artifacts common to both signals. We pulsed blue (450 ± 10 nm) and cyan (505 ± 15 nm) light emitting diodes (LEDs) at 375 Hz in alternating phase synchronized to a camera (750 frames-per-second). Fluorescence was bandpass filtered (585 ± 20 nm). This produced signals with upright (blue) and inverted (cyan) action potentials (APs) interleaved in sequential frames. In four whole swine hearts with motion chemically arrested, fractional fluorescence for blue, cyan, and ratio signals was 1.2 ± 0.3%, 1.2 ± 0.3%, and 2.4 ± 0.6%, respectively. Signal-to-noise ratios were 4.3 ± 1.4, 4.0 ± 1.2, and 5.8 ± 1.9, respectively. After washing out the electromechanical uncoupling agent, we characterized motion artifact by cross-correlating blue, cyan, and ratio signals with a signal with normal AP morphology. Ratiometry improved cross-correlation coefficients from 0.50 ± 0.48 to 0.81 ± 0.25, but did not cancel all motion artifacts. These findings demonstrate the feasibility of pulsed LED excitation ratiometry in myocardium.
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Quantitative assessment of peptide–lipid interactions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1999-2012. [DOI: 10.1016/j.bbamem.2010.07.012] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2010] [Revised: 07/13/2010] [Accepted: 07/13/2010] [Indexed: 11/23/2022]
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31
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Roche Y, Klymchenko AS, Gerbeau-Pissot P, Gervais P, Mély Y, Simon-Plas F, Perrier-Cornet JM. Behavior of plant plasma membranes under hydrostatic pressure as monitored by fluorescent environment-sensitive probes. BIOCHIMICA ET BIOPHYSICA ACTA 2010; 1798:1601-7. [PMID: 20381451 DOI: 10.1016/j.bbamem.2010.03.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 03/29/2010] [Accepted: 03/31/2010] [Indexed: 01/25/2023]
Abstract
We monitored the behavior of plasma membrane (PM) isolated from tobacco cells (BY-2) under hydrostatic pressures up to 3.5kbar at 30 degrees C, by steady-state fluorescence spectroscopy using the newly introduced environment-sensitive probe F2N12S and also Laurdan and di-4-ANEPPDHQ. The consequences of sterol depletion by methyl-beta-cyclodextrin were also studied. We found that application of hydrostatic pressure led to a marked decrease of hydration as probed by F2N12S and to an increase of the generalized polarization excitation (GPex) of Laurdan. We observed that the hydration effect of sterol depletion was maximal between 1 and 1.5 kbar but was much less important at higher pressures (above 2 kbar) where both parameters reached a plateau value. The presence of a highly dehydrated gel state, insensitive to the sterol content, was thus proposed above 2.5 kbar. However, the F2N12S polarity parameter and the di-4-ANEPPDHQ intensity ratio showed strong effect on sterol depletion, even at very high pressures (2.5-3.5 kbar), and supported the ability of sterols to modify the electrostatic properties of membrane, notably its dipole potential, in a highly dehydrated gel phase. We thus suggested that BY-2 PM undergoes a complex phase behavior in response to the hydrostatic pressure and we also emphasized the role of phytosterols to regulate the effects of high hydrostatic pressure on plant PM.
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Affiliation(s)
- Yann Roche
- Laboratoire Plantes-Microbe-Environnement, UMR INRA 1088/CNRS 5184/Université de Bourgogne, Dijon, France
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Matos PM, Castanho MARB, Santos NC. HIV-1 fusion inhibitor peptides enfuvirtide and T-1249 interact with erythrocyte and lymphocyte membranes. PLoS One 2010; 5:e9830. [PMID: 20352107 PMCID: PMC2843717 DOI: 10.1371/journal.pone.0009830] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2009] [Accepted: 03/02/2010] [Indexed: 11/18/2022] Open
Abstract
Enfuvirtide and T-1249 are two HIV-1 fusion inhibitor peptides that bind to gp41 and prevent its fusogenic conformation, inhibiting viral entry into host cells. Previous studies established the relative preferences of these peptides for membrane model systems of defined lipid compositions. We aimed to understand the interaction of these peptides with the membranes of erythrocytes and peripheral blood mononuclear cells. The peptide behavior toward cell membranes was followed by di-8-ANEPPS fluorescence, a lipophilic probe sensitive to the changes in membrane dipole potential. We observed a fusion inhibitor concentration-dependent decrease on the membrane dipole potential. Quantitative analysis showed that T-1249 has an approximately eight-fold higher affinity towards cells, when compared with enfuvirtide. We also compared the binding towards di-8-ANEPPS labeled lipid vesicles that model cell membranes and obtained concordant results. We demonstrated the distinct enfuvirtide and T-1249 membranotropism for circulating blood cells, which can be translated to a feasible in vivo scenario. The enhanced interaction of T-1249 with cell membranes correlates with its higher efficacy, as it can increase and accelerate the drug binding to gp41 in its pre-fusion state.
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Affiliation(s)
- Pedro M. Matos
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - Miguel A. R. B. Castanho
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - Nuno C. Santos
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
- * E-mail:
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Electrochromism and Solvatochromism in Fluorescence Response of Organic Dyes: A Nanoscopic View. SPRINGER SERIES ON FLUORESCENCE 2010. [DOI: 10.1007/978-3-642-04702-2_9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Pérez-Berná AJ, Pabst G, Laggner P, Villalaín J. Biophysical characterization of the fusogenic region of HCV envelope glycoprotein E1. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:2183-93. [PMID: 19698697 DOI: 10.1016/j.bbamem.2009.08.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Revised: 07/27/2009] [Accepted: 08/04/2009] [Indexed: 01/08/2023]
Abstract
We have studied the binding and interaction of the peptide E1(FP) with various model membranes. E1(FP) is derived from the amino acid segment 274-291 of the hepatitis C virus envelope glycoprotein E1, which was previously proposed to host the peptide responsible for fusion to target membranes. In the present study we addressed the changes which take place upon E1(FP) binding in both the peptide and the phospholipid bilayer, respectively, through a series of complementary experiments. We show that peptide E1(FP) binds to and interacts with phospholipid model membranes, modulates the polymorphic phase behavior of membrane phospholipids, is localized in a shallow position in the membrane and interacts preferentially with cholesterol. The capability of modifying the biophysical properties of model membranes supports its role in HCV-mediated membrane fusion and suggests that the mechanism of membrane fusion elicited by class I and II fusion proteins might be similar.
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Affiliation(s)
- Ana J Pérez-Berná
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, E-03202 Alicante, Spain
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35
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Demchenko AP, Mély Y, Duportail G, Klymchenko AS. Monitoring biophysical properties of lipid membranes by environment-sensitive fluorescent probes. Biophys J 2009; 96:3461-70. [PMID: 19413953 DOI: 10.1016/j.bpj.2009.02.012] [Citation(s) in RCA: 301] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2009] [Revised: 02/11/2009] [Accepted: 02/17/2009] [Indexed: 01/21/2023] Open
Abstract
We review the main trends in the development of fluorescence probes to obtain information about the structure, dynamics, and interactions in biomembranes. These probes are efficient for studying the microscopic analogs of viscosity, polarity, and hydration, as well as the molecular order, environment relaxation, and electrostatic potentials at the sites of their location. Progress is being made in increasing the information content and spatial resolution of the probe responses. Multichannel environment-sensitive probes that can distinguish between different membrane physicochemical properties through multiple spectroscopic parameters show considerable promise.
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36
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Demchenko AP, Yesylevskyy SO. Nanoscopic description of biomembrane electrostatics: results of molecular dynamics simulations and fluorescence probing. Chem Phys Lipids 2009; 160:63-84. [PMID: 19481071 DOI: 10.1016/j.chemphyslip.2009.05.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Revised: 05/18/2009] [Accepted: 05/19/2009] [Indexed: 12/21/2022]
Abstract
Electrostatic fields generated on and inside biological membranes are recognized to play a fundamental role in key processes of cell functioning. Their understanding requires an adequate description on the level of elementary charges and the reconstruction of electrostatic potentials by integration over all elementary interactions. Out of all the available research tools, only molecular dynamics simulations are capable of this, extending from the atomic to the mesoscopic level of description on the required time and space scale. A complementary approach is that offered by molecular probe methods, with the application of electrochromic dyes. Highly sensitive to intermolecular interactions, they generate integrated signals arising from electric fields produced by elementary charges at the sites of their location. This review is an attempt to provide a critical analysis of these two approaches and their present and potential applications. The results obtained by both methods are consistent in that they both show an extremely complex profile of the electric field in the membrane. The nanoscopic view, with two-dimensional averaging over the bilayer plane and formal separation of the electrostatic potential into surface (Psi(s)), dipole (Psi(d)) and transmembrane (Psi(t)) potentials, is constructive in the analysis of different functional properties of membranes.
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Affiliation(s)
- Alexander P Demchenko
- A.V. Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Leontovicha St. 9, Kiev 01601, Ukraine.
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Starke-Peterkovic T, Clarke RJ. Effect of headgroup on the dipole potential of phospholipid vesicles. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2009; 39:103-10. [PMID: 19132364 DOI: 10.1007/s00249-008-0392-y] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Revised: 12/01/2008] [Accepted: 12/08/2008] [Indexed: 11/25/2022]
Abstract
The dipole potentials, psi (d), of phospholipid vesicles composed of pure dimyristoylphosphatidylcholine (DMPC) or vesicles in which 50 mol% of the DMPC was substituted by dimyristoylphosphatidylserine (DMPS), dimyristoylphosphatidylglycerol (DMPG), dimyristoylethanolamine (DMPE), dimyristoylphosphatidic acid (DMPA) or monomyristoylphosphatidylcholine (MMPC) were measured via a fluorescent ratiometric method utilizing the probe di-8-ANEPPS. The PS and PG headgroups were found to cause only minor changes in psi (d). PE caused an increase in psi (d) of 51 mV. This could be explained by a decrease in the dielectric constant of the glycerol backbone region as well as a movement of the P(-)-N(+) dipole of the less bulky PE headgroup to a position more parallel to the membrane surface than in PC. The negatively charged PA headgroup increases psi (d) by 215 mV relative to PC alone. This indicates that the positive pole of the dipole predominantly responsible for the dipole potential is located at a position closer to the interior of the membrane than the phosphate group. The increase in the charge of the negative pole of the dipole by the phosphate group of PA increases the electrical potential drop across the lipid headgroup region. The incorporation of the single chain lipid MMPC into the membrane causes a decrease in psi (d) of 142 mV. This can be explained by a decrease in packing density within the membrane of carbonyl dipoles from the sn-2 chain of DMPC. The results presented should contribute to a better understanding of the electrical effect of lipid headgroups on the functioning of membrane proteins.
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Membrane dipole potential of interaction between amyloid protein and phospholipid membranes is dependent on protein aggregation state. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/j.jcice.2008.03.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Matos PM, Gonçalves S, Santos NC. Interaction of peptides with biomembranes assessed by potential-sensitive fluorescent probes. J Pept Sci 2008; 14:407-15. [PMID: 18189333 DOI: 10.1002/psc.1005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Peptide-membrane interaction is an important step to be evaluated in a study of the activity and mode of action of several bioactive peptides. A variety of methods are available; however, few of them satisfy the criteria of being sensitive, biocompatible, versatile, easy to perform, and allowing real-time monitoring as the use of potential-sensitive fluorescent probes. Here we review methods for detecting the effects of membrane-active peptides, even those that are not intrinsically fluorescent, on the different types of membrane potentials, with a special emphasis on studies conducted with living cells. FPE is a probe sensitive to surface potential and detects electrostatic interactions at the water-lipid interface. Di-8-ANEPPS is sensitive to dipole potential and detects membrane incorporations. Transmembrane potential changes reveal major membrane destabilizations, such as in pore formation. The combination of the information obtained from the three potential variations can lead to a more elucidative picture of the mechanisms of the interaction of relevant peptides with biomembranes.
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Affiliation(s)
- Pedro M Matos
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal
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Protolytic equilibrium in lyophilic nanosized dispersions: Differentiating influence of the pseudophase and salt effects. PURE APPL CHEM 2008. [DOI: 10.1351/pac200880071459] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The so-called apparent ionization constants of various acids (mainly indicator dyes) in versatile organized solutions are analyzed. Aqueous micellar solutions of colloidal surfactants and related lyophilic colloidal systems display a strong differentiating influence on the acidic strength of indicators located in the dispersed pseudophase, i.e., non-uniform changes of pKa on going from water to the given system. This concept allows the influence of such media on acid-base properties of dissolved reagents to be rationalized. It is demonstrated that the differentiating phenomenon is the main reason for limitation of the common electrostatic model of acid-base interactions, and is the principal hindrance to exact evaluations of the interfacial electrical potentials of ionic micelles by means of acid-base indicators. Salt effects, i.e., the influence of supporting electrolytes on the apparent ionization constants of acid-base indicators in the Stern region of ionic micelles, are considered. These salt effects can be conventionally divided into two kinds, namely, general (normal) and special (specific) effects. While the first type adds up to screening of the surface charge, the second one consists in micellar transitions caused by hydrophobic counterions.
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Wu SN, Lin MW, Wang YJ. Stimulatory actions of di-8-butyl-amino-naphthyl-ethylene-pyridinium-propyl-sulfonate (di-8-ANEPPS), voltage-sensitive dye, on the BKCa channel in pituitary tumor (GH3) cells. Pflugers Arch 2007; 455:687-99. [PMID: 17701422 DOI: 10.1007/s00424-007-0329-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Revised: 07/16/2007] [Accepted: 07/24/2007] [Indexed: 11/29/2022]
Abstract
Di-8-ANEPPS (4-{2-[6-(dibutylamino)-2-naphthalenyl]-ethenyl}-1-(3-sulfopropyl)pyridinium inner salt) has been used as a fast-response voltage-sensitive styrylpyridinium probe. However, little is known regarding the mechanism of di-8-ANEPPS actions on ion currents. In this study, the effects of this dye on ion currents were investigated in pituitary GH(3) cells. In whole-cell configuration, di-8-ANEPPS (10 microM) reversibly increased the amplitude of Ca(2+)-activated K(+) current. In inside-out configuration, di-8-ANEPPS (10 microM) applied to the intracellular surface of the membrane caused no change in single-channel conductance; however, it did enhance the activity of large-conductance Ca(2+)-activated K(+) (BK(Ca)) channels with an EC(50) value of 7.5 microM. This compound caused a left shift in the activation curve of BK(Ca) channels with no change in the gating charge of these channels. A decrease in mean closed time of the channels was seen in the presence of this dye. In the cell-attached mode, di-8-ANEPPS applied on the extracellular side of the membrane also activated BK(Ca) channels. However, neither voltage-gated K(+) nor ether-à-go-go-related gene (erg)-mediated K(+) currents in GH(3) cells were affected by di-8-APPNES. Under current-clamp configuration, di-8-ANEPPS (10 microM) decreased the firing of action potentials in GH(3) cells. In pancreatic betaTC-6 cells, di-8-APPNES (10 microM) also increased BK(Ca)-channel activity. Taken together, this study suggests that during the exposure to di-8-ANEPPS, the stimulatory effects on BK(Ca) channels could be one of potential mechanisms through which it may affect cell excitability.
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Affiliation(s)
- Sheng-Nan Wu
- Department of Physiology, National Cheng Kung University Medical College, No. 1, University Road, Tainan 70101 Taiwan, Republic of China.
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