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Ermakov YA. Electric Fields at the Lipid Membrane Interface. MEMBRANES 2023; 13:883. [PMID: 37999369 PMCID: PMC10673053 DOI: 10.3390/membranes13110883] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 11/13/2023] [Accepted: 11/14/2023] [Indexed: 11/25/2023]
Abstract
This review presents a comprehensive analysis of electric field distribution at the water-lipid membrane interface in the context of its relationship to various biochemical problems. The main attention is paid to the methodological aspects of bioelectrochemical techniques and quantitative analysis of electrical phenomena caused by the ionization and hydration of the membrane-water interface associated with the phase state of lipids. One of the objectives is to show the unique possibility of controlling changes in the structure of the lipid bilayer initiated by various membrane-active agents that results in electrostatic phenomena at the surface of lipid models of biomembranes-liposomes, planar lipid bilayer membranes (BLMs) and monolayers. A set of complicated experimental facts revealed in different years is analyzed here in order of increasing complexity: from the adsorption of biologically significant inorganic ions and phase rearrangements in the presence of multivalent cations to the adsorption and incorporation of pharmacologically significant compounds into the lipid bilayer, and formation of the layers of macromolecules of different types.
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Affiliation(s)
- Yury A Ermakov
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow 119071, Russia
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2
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Banerjee T, Biswas D, Pal DS, Miao Y, Iglesias PA, Devreotes PN. Spatiotemporal dynamics of membrane surface charge regulates cell polarity and migration. Nat Cell Biol 2022; 24:1499-1515. [PMID: 36202973 PMCID: PMC10029748 DOI: 10.1038/s41556-022-00997-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 08/18/2022] [Indexed: 12/12/2022]
Abstract
During cell migration and polarization, numerous signal transduction and cytoskeletal components self-organize to generate localized protrusions. Although biochemical and genetic analyses have delineated many specific interactions, how the activation and localization of so many different molecules are spatiotemporally orchestrated at the subcellular level has remained unclear. Here we show that the regulation of negative surface charge on the inner leaflet of the plasma membrane plays an integrative role in the molecular interactions. Surface charge, or zeta potential, is transiently lowered at new protrusions and within cortical waves of Ras/PI3K/TORC2/F-actin network activation. Rapid alterations of inner leaflet anionic phospholipids-such as PI(4,5)P2, PI(3,4)P2, phosphatidylserine and phosphatidic acid-collectively contribute to the surface charge changes. Abruptly reducing the surface charge by recruiting positively charged optogenetic actuators was sufficient to trigger the entire biochemical network, initiate de novo protrusions and abrogate pre-existing polarity. These effects were blocked by genetic or pharmacological inhibition of key signalling components such as AKT and PI3K/TORC2. Conversely, increasing the negative surface charge deactivated the network and locally suppressed chemoattractant-induced protrusions or subverted EGF-induced ERK activation. Computational simulations involving excitable biochemical networks demonstrated that slight changes in feedback loops, induced by recruitment of the charged actuators, could lead to outsized effects on system activation. We propose that key signalling network components act on, and are in turn acted upon, by surface charge, closing feedback loops, which bring about the global-scale molecular self-organization required for spontaneous protrusion formation, cell migration and polarity establishment.
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Affiliation(s)
- Tatsat Banerjee
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- Department of Chemical and Biomolecular Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Debojyoti Biswas
- Department of Electrical and Computer Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Dhiman Sankar Pal
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Yuchuan Miao
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- Department of Biological Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Pablo A Iglesias
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- Department of Electrical and Computer Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Peter N Devreotes
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
- Department of Biological Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
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3
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Electrostatic influence on IL-1 transport through the GSDMD pore. Proc Natl Acad Sci U S A 2022; 119:2120287119. [PMID: 35115408 PMCID: PMC8833203 DOI: 10.1073/pnas.2120287119] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/03/2022] [Indexed: 12/11/2022] Open
Abstract
A variety of signals, including inflammasome activation, trigger the formation of large transmembrane pores by gasdermin D (GSDMD). There are primarily two functions of the GSDMD pore, to drive lytic cell death, known as pyroptosis, and to permit the release of leaderless interleukin-1 (IL-1) family cytokines, a process that does not require pyroptosis. We are interested in the mechanism by which the GSDMD pore channels IL-1 release from living cells. Recent studies revealed that electrostatic interaction, in addition to cargo size, plays a critical role in GSDMD-dependent protein release. Here, we determined computationally that to enable electrostatic filtering against pro-IL-1β, acidic lipids in the membrane need to effectively neutralize positive charges in the membrane-facing patches of the GSDMD pore. In addition, we predicted that salt has an attenuating effect on electrostatic filtering and then validated this prediction using a liposome leakage assay. A calibrated electrostatic screening factor is necessary to account for the experimental observations, suggesting that ion distribution within the pore may be different from the bulk solution. Our findings corroborate the electrostatic influence of IL-1 transport exerted by the GSDMD pore and reveal extrinsic factors, including lipid and salt, that affect the electrostatic environment.
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4
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Halder A, Karmakar S. An evidence of pores in phospholipid membrane induced by an antimicrobial peptide NK-2. Biophys Chem 2022; 282:106759. [PMID: 35008010 DOI: 10.1016/j.bpc.2022.106759] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/27/2021] [Accepted: 01/02/2022] [Indexed: 11/19/2022]
Abstract
NK-2, a peptide derived from a cationic core region of NK-lysin, has emerged as a promising candidate for new antibiotics. In contrast to classical antibiotics, antimicrobial peptides target bacterial membranes and disintegrate the membrane by forming the transmembrane pores. However, complete understanding of the precise mechanisms of cellular apoptosis and molecular basis of membrane selectivity is still in dispute. In the present study, we have shown that NK-2 forms trans-membrane pores on negatively charged phospholipid membranes using phase contrast microscopy. As bacteria mimicking membranes, we have chosen large unilamellar vesicles (LUV) and giant unilamellar vesicles (GUV) composed of negatively charged phospholipid, dioleoyl phosphatidyl glycerol (DOPG) and neutral phospholipid, dioleoyl phophatidylcholine (DOPC). Leakage of internal fluid of giant unilamellar vesicles (GUV), leading to decrease in intensity in the halo region of phase contrast micrographs, suggests the formation of transmembrane pores. No such reduction of intensity in the halo region of DOPC was observed, indicating, neutral vesicles does not exhibit pores. Rate constant reckoned from the decaying intensity in the halo region was found to be 0.007 s-1. Further, significant interaction of NK-2 with anionic membranes has been envisaged from zeta potential and dynamic light scattering. Binding free energy and other interaction parameters have been delineated using theoretical ansatz. A proliferation of average Size of anionic LUV on increasing NK-2 concentration indicates membrane-membrane interaction leading to peptide induced large aggregates of vesicles.
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Affiliation(s)
- Animesh Halder
- Soft matter and Biophysics Laboratory, Department of Physics, Jadavpur University, 188, Raja S. C. Mullick Road, Kolkata 700032, India
| | - Sanat Karmakar
- Soft matter and Biophysics Laboratory, Department of Physics, Jadavpur University, 188, Raja S. C. Mullick Road, Kolkata 700032, India.
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5
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Vogt S, Stadlmayr G, Stadlbauer K, Stracke F, Bobbili MR, Grillari J, Rüker F, Wozniak-Knopp G. Construction of Yeast Display Libraries for Selection of Antigen-Binding Variants of Large Extracellular Loop of CD81, a Major Surface Marker Protein of Extracellular Vesicles. Methods Mol Biol 2022; 2491:561-592. [PMID: 35482205 DOI: 10.1007/978-1-0716-2285-8_24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Over the last two decades, yeast display methodology has served as a popular tool for discovery, humanization, stability improvement, and affinity maturation of antibodies and antibody fragments, but also for development of diverse non-antibody protein scaffolds towards the ability of antigen recognition. Yeast display is particularly well suited for multiparametric analysis of properties of derivatized proteins, allowing the evolution of most diverse protein structures into antigen binding entities with favorable expression, stability, and folding properties. Here we present the methodological basics of a novel yeast display-based approach for the functionalization of the large extracellular loop of CD81 into a de novo antigen binding unit. CD81 is intrinsically overrepresented on the surface of extracellular vesicles (EVs), naturally occurring nanoparticle units that act as cell-to-cell messengers by delivering their intracellular cargo from the source cell into a recipient cell. This amazing feature makes them of highest biotechnological interest, yet methods for their targeted delivery are still in their infancy. As a novel approach for introducing EV surface modifications enabling specific target cell recognition and internalization, we have prepared yeast display libraries of CD81 large extracellular loop mutants, which are selected towards specific antigen binding and resulting mutants conveniently clicked into the full-length EV surface protein. Resulting EVs display wild-type-like characteristics regarding the expression level and distribution of recombinant proteins and are hence promising therapeutic tools.
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Affiliation(s)
- Stefan Vogt
- acib GmbH (Austrian Centre of Industrial Biotechnology), Graz, Austria
- Institute of Molecular Biotechnology, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna (BOKU), Vienna, Austria
| | - Gerhard Stadlmayr
- Christian Doppler Laboratory for Innovative Immunotherapeutics, Institute of Molecular Biotechnology, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna (BOKU), Vienna, Austria
| | - Katharina Stadlbauer
- Christian Doppler Laboratory for Innovative Immunotherapeutics, Institute of Molecular Biotechnology, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna (BOKU), Vienna, Austria
| | - Florian Stracke
- Christian Doppler Laboratory for Innovative Immunotherapeutics, Institute of Molecular Biotechnology, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna (BOKU), Vienna, Austria
| | - Madhusudhan Reddy Bobbili
- Institute of Molecular Biotechnology, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna (BOKU), Vienna, Austria
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology in the AUVA Research Center, Vienna, Austria
| | - Johannes Grillari
- Institute of Molecular Biotechnology, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna (BOKU), Vienna, Austria
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology in the AUVA Research Center, Vienna, Austria
- Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Florian Rüker
- Institute of Molecular Biotechnology, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna (BOKU), Vienna, Austria
| | - Gordana Wozniak-Knopp
- Christian Doppler Laboratory for Innovative Immunotherapeutics, Institute of Molecular Biotechnology, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna (BOKU), Vienna, Austria.
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6
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Hadidi H, Kamali R. Molecular dynamics study of water transport through AQP5-R188C mutant causing palmoplantar keratoderma (PPK) using the gating mechanism concept. Biophys Chem 2021; 277:106655. [PMID: 34225022 DOI: 10.1016/j.bpc.2021.106655] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 06/25/2021] [Accepted: 06/25/2021] [Indexed: 01/05/2023]
Abstract
It is widely known that any disruption to the water regulation in aquaporins (AQPs) leads to numerous important diseases. However, studies of dynamics and energetics of disease-causing mutations in the aquaporins on the molecular level are still limited. In the present work, the effects of a skin disease-causing mutant, R188C, on the structure of AQP5 and water transport mechanism within this mutated aquaporin are investigated using the concept of gating mechanism. Our results have revealed that the R188C mutation causes a remarkable increase in the pore radius inside the selectivity filter (SF) region facilitating the passage of water molecules. This observation is supported by plotting the free energy profiles of water molecules transport and calculating permeability values through AQP5-R188C, such that the energy barrier in the SF region of the pores was substantially reduced by this mutation, and therefore, the translocation of water molecules was improved. The total averaged osmotic permeability for R188C has been computed as about 11-fold of the wild-type permeability. However, a comparison between the osmotic permeability values related to the open conformation of CE revealed that this coefficient for AQP5-R188C is about 6.5 times larger than that of wt-AQP5, which can be a more accurate value according to the gating mechanism associated with the constriction region of the aquaporin.
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Affiliation(s)
- Hooman Hadidi
- School of Mechanical Engineering, Shiraz University, Shiraz, Fars 71348-51154, Iran
| | - Reza Kamali
- School of Mechanical Engineering, Shiraz University, Shiraz, Fars 71348-51154, Iran.
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7
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Inhomogeneity of polylysine adsorption layers on lipid membranes revealed by theoretical analysis of electrokinetic data and molecular dynamics simulations. Bioelectrochemistry 2021; 141:107828. [PMID: 34020399 DOI: 10.1016/j.bioelechem.2021.107828] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Revised: 04/19/2021] [Accepted: 04/20/2021] [Indexed: 11/22/2022]
Abstract
The adsorption of large polycations on a charged lipid membrane is qualitatively different from the small inorganic cations, which almost uniformly populate the membrane surface. We assume that the polycationic adsorption layer might be laterally inhomogeneous starting from a certain polymer length, and this effect can be more visible for membranes with low anionic lipid content. To study systems with inhomogeneous adsorption layers, we carried out electrokinetic measurements of mobility of liposomes containing anionic and neutral phospholipids in the presence of polylysine molecules. Some of these systems were simulated by all-atom molecular dynamics. Here we proposed a theoretical approach accounting for the formation of separated regions at the membrane surface, which differ in charge density and surface potential. Our model allowed us to determine the adsorption layer's geometric parameters such as surface coverage and surface-bound monomer fraction of polymer, which correlate with the molecular dynamics (MD) simulations. We demonstrated that the configuration polylysine adopts on the membrane surface (tall or planar) depends on the polymer/membrane charge ratio. Both theory and MD indicate a decrease in the anionic lipid content, alongside with a decrease in the bound monomer fraction and corresponding increase in the extension length of the adsorbed polymers.
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8
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Svirina A, Terterov I. Electrostatic effects in saturation of membrane binding of cationic cell-penetrating peptide. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2021; 50:15-23. [PMID: 33245398 DOI: 10.1007/s00249-020-01476-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 08/17/2020] [Accepted: 11/07/2020] [Indexed: 12/01/2022]
Abstract
Membrane-active peptides that demonstrate cell-penetrating, antimicrobial or cytotoxic functions are diverse in their amino acid sequences, but share common physicochemical features like short length, amphipathic conformation in membrane environment and high net charge. Nonspecific electrostatic interactions of basic peptide residues with anionic membrane lipids play a crucial role in the initial binding of such peptides to plasma membranes of bacterial and mammalian cells. At the same time, a number of membrane-active peptides functions when they are localized at high concentrations on the lipid membranes. Dissecting the role of electrostatics in this functional peptide conditions is important to understand why the majority of them bear high positive charge. We have studied interaction of EB1 cell-penetrating peptide (charge + 8) with model anionic membranes. The saturation of peptide binding to liposomes that comprises 5%, 10% and 25% of negatively charged lipids (POPC/POPG mixture) was observed. We have found that peptide recharges liposomes and its surface saturating concentration increases with the amount of anionic lipids in a membrane so as a surface charge (bound peptide plus anionic lipids). This observation may be explained with the Gouy-Chapman theory based model with addition of independent effective peptide charges for peptide-peptide and peptide-lipid interactions, as well as steric saturation term. Additionally, in certain conditions, membrane bound peptide leads to liposome aggregation. In some lipid-to-peptide ratio regions disaggregation follows that may indicate an additional slow equilibration process after fast initial peptide binding.
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Affiliation(s)
- Anna Svirina
- Saint Petersburg Academic University, St. Petersburg, Russia.
- B CUBE-Molecular Bioengineering, Dresden, Germany.
| | - Ivan Terterov
- Saint-Petersburg Clinical Scientific and Practical Center of Specialized Types of Medical Care (Oncological), St. Petersburg, Russia
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9
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Rathore SS, Liu Y, Yu H, Wan C, Lee M, Yin Q, Stowell MHB, Shen J. Intracellular Vesicle Fusion Requires a Membrane-Destabilizing Peptide Located at the Juxtamembrane Region of the v-SNARE. Cell Rep 2019; 29:4583-4592.e3. [PMID: 31875562 PMCID: PMC6990648 DOI: 10.1016/j.celrep.2019.11.107] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 10/13/2019] [Accepted: 11/26/2019] [Indexed: 12/11/2022] Open
Abstract
Intracellular vesicle fusion is mediated by soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNAREs) and Sec1/Munc18 (SM) proteins. It is generally accepted that membrane fusion occurs when the vesicle and target membranes are brought into close proximity by SNAREs and SM proteins. In this work, we demonstrate that, for fusion to occur, membrane bilayers must be destabilized by a conserved membrane-embedded motif located at the juxtamembrane region of the vesicle-anchored v-SNARE. Comprised of basic and hydrophobic residues, the juxtamembrane motif perturbs the lipid bilayer structure and promotes SNARE-SM-mediated membrane fusion. The juxtamembrane motif can be functionally substituted with an unrelated membrane-disrupting peptide in the membrane fusion reaction. These findings establish the juxtamembrane motif of the v-SNARE as a membrane-destabilizing peptide. Requirement of membrane-destabilizing peptides is likely a common feature of biological membrane fusion.
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Affiliation(s)
- Shailendra S Rathore
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, 347 UCB, Boulder, CO 80309, USA
| | - Yinghui Liu
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, 347 UCB, Boulder, CO 80309, USA; Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Haijia Yu
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, 347 UCB, Boulder, CO 80309, USA; Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China.
| | - Chun Wan
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, 347 UCB, Boulder, CO 80309, USA
| | - MyeongSeon Lee
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, 347 UCB, Boulder, CO 80309, USA
| | - Qian Yin
- Department of Biological Sciences and Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
| | - Michael H B Stowell
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, 347 UCB, Boulder, CO 80309, USA
| | - Jingshi Shen
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, 347 UCB, Boulder, CO 80309, USA.
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10
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Electrostatically Driven Encapsulation of Hydrophilic, Non-Conformational Peptide Epitopes into Liposomes. Pharmaceutics 2019; 11:pharmaceutics11110619. [PMID: 31752070 PMCID: PMC6920922 DOI: 10.3390/pharmaceutics11110619] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 11/01/2019] [Accepted: 11/12/2019] [Indexed: 12/13/2022] Open
Abstract
Since the first use of liposomes as carriers for antigens, much work has been done to elucidate the mechanisms involved in the encapsulation of vaccine-relevant biomolecules. However, only a few studies have specifically investigated the encapsulation of hydrophilic, non-conformational peptide epitopes. We performed comprehensive and systematic screening studies, in order to identify conditions that favor the electrostatic interaction of such peptides with lipid membranes. Moreover, we have explored bi-terminal sequence extension as an approach to modify the isoelectric point of peptides, in order to modulate their membrane binding behavior and eventually shift/expand the working range under which they can be efficiently encapsulated in an electrostatically driven manner. The findings of our membrane interaction studies were then applied to preparing peptide-loaded liposomes. Our results show that the magnitude of membrane binding observed in our exploratory in situ setup translates to corresponding levels of encapsulation efficiency in both of the two most commonly employed methods for the preparation of liposomes, i.e., thin-film hydration and microfluidic mixing. We believe that the methods and findings described in the present studies will be of use to a wide audience and can be applied to address the ongoing relevant issue of the efficient encapsulation of hydrophilic biomolecules.
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11
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Imranpasha, Kumar B. Kinetics of interaction between antimicrobial peptide nisin and Langmuir monolayers of DPPC and DPPG molecules. Phys Rev E 2019; 100:032404. [PMID: 31640048 DOI: 10.1103/physreve.100.032404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Indexed: 11/07/2022]
Abstract
We have studied the kinetics of the interaction between antimicrobial peptide nisin and Langmuir monolayers of phospholipids DPPC and DPPG at the air-water interface using the surface manometry technique. The charge on the nisin and the lipid molecules is controlled by varying the pH of the subphase, and the interactions between them are studied by measuring the surface pressure of the lipid monolayer as a function of time after injecting the nisin in the subphase. A model based on the diffusion of particles under the influence of a constant force is developed to obtain an analytical expression for surface pressure as a function of time. The expression was found to fit well with the experimental data. The average hydrodynamic radius and the translational diffusion constant of the nisin molecules are calculated from the fit parameters for the different subphase pH solutions.
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Affiliation(s)
- Imranpasha
- Department of Physics, Central University of Karnataka, Kadaganchi-585367, Kalaburagi, Karnataka, India
| | - Bharat Kumar
- Department of Physics, Central University of Karnataka, Kadaganchi-585367, Kalaburagi, Karnataka, India
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12
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Enkavi G, Javanainen M, Kulig W, Róg T, Vattulainen I. Multiscale Simulations of Biological Membranes: The Challenge To Understand Biological Phenomena in a Living Substance. Chem Rev 2019; 119:5607-5774. [PMID: 30859819 PMCID: PMC6727218 DOI: 10.1021/acs.chemrev.8b00538] [Citation(s) in RCA: 196] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Indexed: 12/23/2022]
Abstract
Biological membranes are tricky to investigate. They are complex in terms of molecular composition and structure, functional over a wide range of time scales, and characterized by nonequilibrium conditions. Because of all of these features, simulations are a great technique to study biomembrane behavior. A significant part of the functional processes in biological membranes takes place at the molecular level; thus computer simulations are the method of choice to explore how their properties emerge from specific molecular features and how the interplay among the numerous molecules gives rise to function over spatial and time scales larger than the molecular ones. In this review, we focus on this broad theme. We discuss the current state-of-the-art of biomembrane simulations that, until now, have largely focused on a rather narrow picture of the complexity of the membranes. Given this, we also discuss the challenges that we should unravel in the foreseeable future. Numerous features such as the actin-cytoskeleton network, the glycocalyx network, and nonequilibrium transport under ATP-driven conditions have so far received very little attention; however, the potential of simulations to solve them would be exceptionally high. A major milestone for this research would be that one day we could say that computer simulations genuinely research biological membranes, not just lipid bilayers.
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Affiliation(s)
- Giray Enkavi
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Matti Javanainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy
of Sciences, Flemingovo naḿesti 542/2, 16610 Prague, Czech Republic
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Waldemar Kulig
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Tomasz Róg
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Ilpo Vattulainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
- MEMPHYS-Center
for Biomembrane Physics
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13
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Irvine WA, Flanagan JU, Allison JR. Computational Prediction of Amino Acids Governing Protein-Membrane Interaction for the PIP3 Cell Signaling System. Structure 2019; 27:371-380.e3. [DOI: 10.1016/j.str.2018.10.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 08/13/2018] [Accepted: 10/18/2018] [Indexed: 10/27/2022]
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14
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Hädicke A, Blume A. Interaction of Short Pentavalent Cationic Peptides with Negatively Charged DPPG Monolayers and Bilayers: Influence of Peptide Modifications on Binding. J Phys Chem B 2018; 122:10522-10534. [PMID: 30371093 DOI: 10.1021/acs.jpcb.8b08667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The binding of oligopeptides with the structure (RX)4R and (KXX)4K, with X being the amino acid G or A, to lipid monolayers and bilayers of dipalmitoyl-phosphatidylglycerol (DPPG) was studied and compared to the binding effects of peptides with the structure (KX)4K. The monolayer adsorption experiments again showed the superposition of condensation effects due to charge compensation and insertion of amino acid side chains leading to expansion of the monolayer. The latter effect was enhanced when glycine was replaced by alanine. The thermotropic phase behavior of dipalmitoyl-phosphatidylglycerol (DPPG) bilayer membranes and their mixtures with short cationic model peptides was investigated by differential scanning calorimetry and infrared spectroscopy. Increasing the charge distance of the lysine residues in the series (K)5, (KG)4K, and (KGG)4K results in an upshift of the main phase transition of DPPG up to 5 K, as predicted for pure electrostatic binding. All peptides exhibit only unordered structures in bulk solution as well as when bound to DPPG bilayers. (KGG)4K additionally shows a high propensity of turn structures due to its flexibility. The exchange of glycine by alanine in (KAA)4K leads only to a marginal increase in Tm, in contrast to the binding of (KA)4K where the formation of intervesicular antiparallel β-sheets occurs, leading to a much more pronounced stabilization of the gel phase. This shows that the sequence and flexibility of the oligopeptides has an important influence on the formation of secondary structures bound to the bilayers. Binding of (RX)4R peptides to DPPG bilayers has almost no influence on the lipid phase transition in bilayers. Here, condensation and insertion effects almost compensate, as the results of monolayer experiments show. This is due to the higher propensity of arginine side chains to insert into the lipid headgroup region.
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Affiliation(s)
- André Hädicke
- Institute of Chemistry , MLU Halle-Wittenberg , von-Danckelmann-Platz 4 , 06120 Halle/Saale , Germany
| | - Alfred Blume
- Institute of Chemistry , MLU Halle-Wittenberg , von-Danckelmann-Platz 4 , 06120 Halle/Saale , Germany
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15
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Binda A, Panariti A, Barbuti A, Murano C, Dal Magro R, Masserini M, Re F, Rivolta I. Modulation of the intrinsic neuronal excitability by multifunctional liposomes tailored for the treatment of Alzheimer's disease. Int J Nanomedicine 2018; 13:4059-4071. [PMID: 30034232 PMCID: PMC6047604 DOI: 10.2147/ijn.s161563] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Purpose Nanotechnologies turned out to be promising in the development of diagnostic and therapeutic approaches toward neurodegenerative disorders. However, only a very scant number of nanodevices until now proved to be effective on preclinical animal models. Although specific tests in vivo are available to assess the potential toxicity of these nanodevices on cognitive functions, those to evaluate their biosafety in vitro on neurons are still to be improved. Materials and methods We utilized the patch-clamp technique on primary cultures of cortical neural cells isolated from neonatal rats, aiming to evaluate their electrical properties after the incubation with liposomes (mApoE-PA-LIPs), previously proved able to cross the blood–brain barrier and to be effective on mouse models of Alzheimer’s disease (AD), both in the absence and in the presence of β-amyloid peptide oligomers. Results Data show a high degree of biocompatibility, evaluated by lactate dehydrogenase (LDH) release and MTT assay, and the lack of cellular internalization. After the incubation with mApoE-PA-LIPs, neuronal membranes show an increase in the input resistance (from 724.14±76 MΩ in untreated population to 886.06±86 MΩ in the treated one), a reduction in the rheobase current (from 29.6±3 to 24.2±3 pA in untreated and treated, respectively), and an increase of the firing frequency, consistent with an ultimate increase in intrinsic excitability. Data obtained after co-incubation of mApoE-PA-LIPs with β-amyloid peptide oligomers suggest a retention of liposome efficacy. Conclusion These data suggest the ability of liposomes to modulate neuronal electrical properties and are compatible with the previously demonstrated amelioration of cognitive functions induced by treatment of AD mice with liposomes. We conclude that this electrophysiological approach could represent a useful tool for nanomedicine to evaluate the effect of nanoparticles on intrinsic neuronal excitability.
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Affiliation(s)
- Anna Binda
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy,
| | - Alice Panariti
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy,
| | - Andrea Barbuti
- Department of Biosciences, The PaceLab and Interuniversity Center of Molecular Medicine and Applied Biophysics (CIMMBA), University of Milan, Milano, Italy
| | - Carmen Murano
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy,
| | - Roberta Dal Magro
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy,
| | - Massimo Masserini
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy, .,Milan Center for Neuroscience (NeuroMI), University of Milano-Bicocca, Monza, Italy, .,Nanomedicine Center NANOMIB, University of Milano-Bicocca, Milano, Italy,
| | - Francesca Re
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy, .,Milan Center for Neuroscience (NeuroMI), University of Milano-Bicocca, Monza, Italy, .,Nanomedicine Center NANOMIB, University of Milano-Bicocca, Milano, Italy,
| | - Ilaria Rivolta
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy, .,Milan Center for Neuroscience (NeuroMI), University of Milano-Bicocca, Monza, Italy, .,Nanomedicine Center NANOMIB, University of Milano-Bicocca, Milano, Italy,
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16
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Cieślik-Boczula K. Influence of resveratrol on interactions between negatively charged DPPC/DPPG membranes and positively charged poly-l-lysine. Chem Phys Lipids 2018; 214:24-34. [PMID: 29842874 DOI: 10.1016/j.chemphyslip.2018.05.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 05/17/2018] [Accepted: 05/26/2018] [Indexed: 01/03/2023]
Abstract
Resveratrol (Res), a natural polyphenol present in different plants and vegetables, exhibits potential therapeutic activity with cardioprotective, antineurodegenerative, antioxidant, and antitumor action. In this study, the effect of Res on the mutual interactions between positively charged poly-l-lysine (PLL) and negatively charged dipalmitoylphosphatidylcholine/dipalmitoylphosphatidylglycerol (DPPC/DPPG) membranes was studied using Fourier-transform infrared (FTIR) spectroscopy supported by principal component analysis (PCA). The interactions between PLL and DPPC/DPPG membranes were strongly affected by the presence of Res molecules. Depending on the Res concentration and method of its supply (through the water or lipid phase) to the studied peptide-membrane systems, the membrane-induced transition of PLL from an α-helix to an extended left-handed polyproline II helix (PPII) occurred at different temperatures, with different cooperativity, or was even completely suppressed. The influence of PLL on the conformational (trans/gauche) state of the hydrocarbon chain region of the lipid membranes and the hydration state of the polar/apolar membrane interface was also modulated by Res, depending on the membrane phase state.
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17
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Case BA, Kruziki MA, Johnson SM, Hackel BJ. Engineered Charge Redistribution of Gp2 Proteins through Guided Diversity for Improved PET Imaging of Epidermal Growth Factor Receptor. Bioconjug Chem 2018; 29:1646-1658. [PMID: 29579383 PMCID: PMC6051758 DOI: 10.1021/acs.bioconjchem.8b00144] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The Gp2 domain is a protein scaffold for synthetic ligand engineering. However, the native protein function results in a heterogeneous distribution of charge on the conserved surface, which may hinder further development and utility. We aim to modulate charge, without diminishing function, which is challenging in small proteins where each mutation is a significant fraction of protein structure. We constructed rationally guided combinatorial libraries with charge-neutralizing or charge-flipping mutations and sorted them, via yeast display and flow cytometry, for stability and target binding. Deep sequencing of functional variants revealed effective mutations both in clone-dependent contexts and broadly across binders to epidermal growth factor receptor (EGFR), insulin receptor, and immunoglobulin G. Functional mutants averaged 4.3 charge neutralizing mutations per domain while maintaining net negative charge. We evolved an EGFR-targeted Gp2 mutant that reduced charge density by 33%, maintained net charge, and improved charge distribution homogeneity while elevating thermal stability ( Tm = 87 ± 1 °C), improving binding specificity, and maintaining affinity ( Kd = 8.8 ± 0.6 nM). This molecule was conjugated with 1,4,7-triazacyclononane,1-glutaric acid-4,7-acetic acid for 64Cu chelation and evaluated for physiological distribution in mice with xenografted A431 (EGFRhigh) and MDA-MB-435 (EGFRlow) tumors. Excised tissue gamma counting and positron emission tomography/computed tomography imaging revealed good EGFRhigh tumor signal (4.7 ± 0.5%ID/g) at 2 h post-injection and molecular specificity evidenced by low uptake in EGFRlow tumors (0.6 ± 0.1%ID/g, significantly lower than for non-charge-modified Gp2, p = 0.01). These results provide charge mutations for an improved Gp2 framework, validate an effective approach to charge engineering, and advance performance of physiological EGFR targeting for molecular imaging.
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Affiliation(s)
- Brett A. Case
- University of Minnesota – Twin Cities, Department of Chemical Engineering and Materials Science, 421 Washington Avenue SE, Minneapolis, MN 55455
| | - Max A. Kruziki
- University of Minnesota – Twin Cities, Department of Chemical Engineering and Materials Science, 421 Washington Avenue SE, Minneapolis, MN 55455
| | - Sadie M. Johnson
- University of Minnesota – Twin Cities, Department of Chemical Engineering and Materials Science, 421 Washington Avenue SE, Minneapolis, MN 55455
| | - Benjamin J. Hackel
- University of Minnesota – Twin Cities, Department of Chemical Engineering and Materials Science, 421 Washington Avenue SE, Minneapolis, MN 55455
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18
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Pal S, Samanta N, Das Mahanta D, Mitra RK, Chattopadhyay A. Effect of Phospholipid Headgroup Charge on the Structure and Dynamics of Water at the Membrane Interface: A Terahertz Spectroscopic Study. J Phys Chem B 2018. [DOI: 10.1021/acs.jpcb.8b01633] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sreetama Pal
- Academy of Scientific and Innovative Research, India
- CSIR-Indian Institute of Chemical Technology, Uppal Road, Hyderabad 500 007, India
| | - Nirnay Samanta
- S.N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 106, India
| | - Debasish Das Mahanta
- S.N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 106, India
| | - Rajib Kumar Mitra
- S.N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 106, India
| | - Amitabha Chattopadhyay
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
- Academy of Scientific and Innovative Research, India
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19
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Khan HM, He T, Fuglebakk E, Grauffel C, Yang B, Roberts MF, Gershenson A, Reuter N. A Role for Weak Electrostatic Interactions in Peripheral Membrane Protein Binding. Biophys J 2016; 110:1367-78. [PMID: 27028646 PMCID: PMC4816757 DOI: 10.1016/j.bpj.2016.02.020] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 01/08/2016] [Accepted: 02/02/2016] [Indexed: 12/01/2022] Open
Abstract
Bacillus thuringiensis phosphatidylinositol-specific phospholipase C (BtPI-PLC) is a secreted virulence factor that binds specifically to phosphatidylcholine (PC) bilayers containing negatively charged phospholipids. BtPI-PLC carries a negative net charge and its interfacial binding site has no obvious cluster of basic residues. Continuum electrostatic calculations show that, as expected, nonspecific electrostatic interactions between BtPI-PLC and membranes vary as a function of the fraction of anionic lipids present in the bilayers. Yet they are strikingly weak, with a calculated ΔGel below 1 kcal/mol, largely due to a single lysine (K44). When K44 is mutated to alanine, the equilibrium dissociation constant for small unilamellar vesicles increases more than 50 times (∼2.4 kcal/mol), suggesting that interactions between K44 and lipids are not merely electrostatic. Comparisons of molecular-dynamics simulations performed using different lipid compositions reveal that the bilayer composition does not affect either hydrogen bonds or hydrophobic contacts between the protein interfacial binding site and bilayers. However, the occupancies of cation-π interactions between PC choline headgroups and protein tyrosines vary as a function of PC content. The overall contribution of basic residues to binding affinity is also context dependent and cannot be approximated by a rule-of-thumb value because these residues can contribute to both nonspecific electrostatic and short-range protein-lipid interactions. Additionally, statistics on the distribution of basic amino acids in a data set of membrane-binding domains reveal that weak electrostatics, as observed for BtPI-PLC, might be a less unusual mechanism for peripheral membrane binding than is generally thought.
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Affiliation(s)
- Hanif M Khan
- Department of Molecular Biology, University of Bergen, Bergen, Norway; Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
| | - Tao He
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts
| | - Edvin Fuglebakk
- Department of Molecular Biology, University of Bergen, Bergen, Norway; Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
| | - Cédric Grauffel
- Department of Molecular Biology, University of Bergen, Bergen, Norway; Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
| | - Boqian Yang
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts; Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts
| | - Mary F Roberts
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts
| | - Anne Gershenson
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts
| | - Nathalie Reuter
- Department of Molecular Biology, University of Bergen, Bergen, Norway; Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway.
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20
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Robison AD, Sun S, Poyton MF, Johnson GA, Pellois JP, Jungwirth P, Vazdar M, Cremer PS. Polyarginine Interacts More Strongly and Cooperatively than Polylysine with Phospholipid Bilayers. J Phys Chem B 2016; 120:9287-96. [PMID: 27571288 PMCID: PMC5912336 DOI: 10.1021/acs.jpcb.6b05604] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The interactions of two highly positively charged short peptide sequences with negatively charged lipid bilayers were explored by fluorescence binding assays and all-atom molecular dynamics simulations. The bilayers consisted of mixtures of phosphatidylglycerol (PG) and phosphatidylcholine (PC) lipids as well as a fluorescence probe that was sensitive to the interfacial potential. The first peptide contained nine arginine repeats (Arg9), and the second one had nine lysine repeats (Lys9). The experimentally determined apparent dissociation constants and Hill cooperativity coefficients demonstrated that the Arg9 peptides exhibited weakly anticooperative binding behavior at the bilayer interface at lower PG concentrations, but this anticooperative effect vanished once the bilayers contained at least 20 mol % PG. By contrast, Lys9 peptides showed strongly anticooperative binding behavior at all PG concentrations, and the dissociation constants with Lys9 were approximately 2 orders of magnitude higher than with Arg9. Moreover, only arginine-rich peptides could bind to the phospholipid bilayers containing just PC lipids. These results along with the corresponding molecular dynamics simulations suggested two important distinctions between the behavior of Arg9 and Lys9 that led to these striking differences in binding and cooperativity. First, the interactions of the guanidinium moieties on the Arg side chains with the phospholipid head groups were stronger than for the amino group. This helped facilitate stronger Arg9 binding at all PG concentrations that were tested. However, at PG concentrations of 20 mol % or greater, the Arg9 peptides came into sufficiently close proximity with each other so that favorable like-charge pairing between the guanidinium moieties could just offset the long-range electrostatic repulsions. This led to Arg9 aggregation at the bilayer surface. By contrast, Lys9 molecules experienced electrostatic repulsion from each other at all PG concentrations. These insights may help explain the propensity for cell penetrating peptides containing arginine to more effectively cross cell membranes in comparison with lysine-rich peptides.
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Affiliation(s)
| | | | | | | | | | - Pavel Jungwirth
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic , Flemingovo nám. 2, Prague 6 16610, Czech Republic
- Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland
| | - Mario Vazdar
- Division of Organic Chemistry and Biochemistry, Rudjer Bošković Institute , P.O.B. 180, HR-10002 Zagreb, Croatia
- Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland
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Calcium and protons affect the interaction of neurotransmitters and anesthetics with anionic lipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2215-2222. [DOI: 10.1016/j.bbamem.2016.06.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 06/16/2016] [Accepted: 06/22/2016] [Indexed: 01/09/2023]
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22
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Ufret-Vincenty CA, Klein RM, Collins MD, Rosasco MG, Martinez GQ, Gordon SE. Mechanism for phosphoinositide selectivity and activation of TRPV1 ion channels. ACTA ACUST UNITED AC 2016; 145:431-42. [PMID: 25918361 PMCID: PMC4411251 DOI: 10.1085/jgp.201511354] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Phosphoinositides bind to a selective site in the proximal C-terminal region to regulate TRPV1. Although PI(4,5)P2 is believed to play an essential role in regulating the activity of numerous ion channels and transporters, the mechanisms by which it does so are unknown. Here, we used the ability of the TRPV1 ion channel to discriminate between PI(4,5)P2 and PI(4)P to localize the region of TRPV1 sequence that interacts directly with the phosphoinositide. We identified a point mutation in the proximal C-terminal region after the TRP box, R721A, that inverted the selectivity of TRPV1. Although the R721A mutation produced only a 30% increase in the EC50 for activation by PI(4,5)P2, it decreased the EC50 for activation by PI(4)P by more than two orders of magnitude. We used chemically induced and voltage-activated phosphatases to determine that PI(4)P continued to support TRPV1 activity even after depletion of PI(4,5)P2 from the plasma membrane. Our data cannot be explained by a purely electrostatic mechanism for interaction between the phosphoinositide and the protein, similar to that of the MARCKS (myristoylated alanine-rich C kinase substrate) effector domain or the EGF receptor. Rather, conversion of a PI(4,5)P2-selective channel to a PI(4)P-selective channel indicates that a structured phosphoinositide-binding site mediates the regulation of TRPV1 activity and that the amino acid at position 721 likely interacts directly with the moiety at the 5′ position of the phosphoinositide.
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Affiliation(s)
| | - Rebecca M Klein
- University of Washington School of Medicine, Seattle, WA 98195
| | | | - Mario G Rosasco
- University of Washington School of Medicine, Seattle, WA 98195
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23
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Hädicke A, Blume A. Binding of Short Cationic Peptides (KX)4K to Negatively Charged DPPG Monolayers: Competition between Electrostatic and Hydrophobic Interactions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:12203-12214. [PMID: 26479457 DOI: 10.1021/acs.langmuir.5b02882] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The influence of the peptide sequence on the binding of short cationic peptides composed of five lysines alternating with uncharged amino acids within the series (KX)4K to negatively charged monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG) was investigated by adsorption experiments in combination with epifluorescence microscopy. To evaluate the impact of electrostatic and hydrophobic contributions, different uncharged amino acids X with increasing hydrophobicity, where X = G (glycine), A (alanine), Abu (α-aminobutyric acid), V (valine), or L (leucine) were introduced into the peptide sequence to tune the peptide hydrophobicity. The adsorption kinetics of these peptides to a DPPG monolayer always showed two superimposed processes, one leading to an increase and another to a decrease of the surface pressure Π. Thus, the plots of the change in Π after peptide binding vs initial surface pressure of the monolayer showed an unusual behavior with maxima and negative changes in Π at high initial Π values. Epifluorescence microscopy confirmed that electrostatic binding of the peptides with a concomitant decrease in Π leads to a condensation of the lipid monolayer and the formation of liquid-condensed (LC) domains even at Π values where the monolayer is supposedly in the liquid-expanded (LE) state. An increase in hydrophobicity of the amino acid X was found to counteract the condensation and an increase in Π upon peptide binding is observed at low Π values, also concomitant with the formation of LC-domains. Compression of monolayers after peptide adsorption at low surface pressure for 4 h leads to a change of the isotherms compared to pure DPPG isotherms. The phase transition of DPPG from LE to LC state is smeared out or is shifted to higher surface pressure. Considerable changes in the shapes of LC-domains were observed after peptide binding. Growth of the LC-domains was hindered in most cases and regular domain patterns were formed. Binding of (KL)4K leads to a decrease in line tension and the formation of extended filaments protruding from initially circular domains.
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Affiliation(s)
- André Hädicke
- Institute of Chemistry, MLU Halle-Wittenberg , von-Danckelmann-Platz 4, 06120 Halle/Saale, Germany
| | - Alfred Blume
- Institute of Chemistry, MLU Halle-Wittenberg , von-Danckelmann-Platz 4, 06120 Halle/Saale, Germany
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24
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Ji C, Zhang Y, Xu P, Xu T, Lou X. Nanoscale Landscape of Phosphoinositides Revealed by Specific Pleckstrin Homology (PH) Domains Using Single-molecule Superresolution Imaging in the Plasma Membrane. J Biol Chem 2015; 290:26978-26993. [PMID: 26396197 DOI: 10.1074/jbc.m115.663013] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Indexed: 11/06/2022] Open
Abstract
Both phosphatidylinositol 4-phosphate (PI4P) and phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) are independent plasma membrane (PM) determinant lipids that are essential for multiple cellular functions. However, their nanoscale spatial organization in the PM remains elusive. Using single-molecule superresolution microscopy and new photoactivatable fluorescence probes on the basis of pleckstrin homology domains that specifically recognize phosphatidylinositides in insulin-secreting INS-1 cells, we report that the PI(4,5)P2 probes exhibited a remarkably uniform distribution in the major regions of the PM, with some sparse PI(4,5)P2-enriched membrane patches/domains of diverse sizes (383 ± 14 nm on average). Quantitative analysis revealed a modest concentration gradient that was much less steep than previously thought, and no densely packed PI(4,5)P2 nanodomains were observed. Live-cell superresolution imaging further demonstrated the dynamic structural changes of those domains in the flat PM and membrane protrusions. PI4P and phosphatidylinositol (3,4,5)-trisphosphate (PI(3,4,5)P3) showed similar spatial distributions as PI(4,5)P2. These data reveal the nanoscale landscape of key inositol phospholipids in the native PM and imply a framework for local cellular signaling and lipid-protein interactions at a nanometer scale.
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Affiliation(s)
- Chen Ji
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705 and
| | - Yongdeng Zhang
- the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Pingyong Xu
- the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Tao Xu
- the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Xuelin Lou
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705 and.
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Influence of temperature, anions and size distribution on the zeta potential of DMPC, DPPC and DMPE lipid vesicles. Colloids Surf B Biointerfaces 2015; 131:54-8. [PMID: 25950496 DOI: 10.1016/j.colsurfb.2015.03.054] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 03/22/2015] [Accepted: 03/25/2015] [Indexed: 11/24/2022]
Abstract
The purpose of the work is to compare the influence of the multilamellarity, phase state, lipid head groups and ionic media on the origin of the surface potential of lipid membranes. With this aim, we present a new analysis of the zeta potential of multilamellar and unilamellar vesicles composed by phosphatidylcholines (PC) and phosphatidylethanolamines (PE) dispersed in water and ionic solutions of polarizable anions, at temperatures below and above the phase transition. In general, the adsorption of anions seems to explain the origin of the zeta potential in vesicles only above the transition temperature (Tc). In this case, the sign of the surface potential is ascribed to a partial orientation of head group moiety toward the aqueous phase. This is noticeable in PC head groups but not in PEs, due to the strong lateral interaction between PO and NH group in PE.
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26
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Zeng J, Eckenrode HM, Dai HL, Wilhelm MJ. Adsorption and transport of charged vs. neutral hydrophobic molecules at the membrane of murine erythroleukemia (MEL) cells. Colloids Surf B Biointerfaces 2015; 127:122-9. [DOI: 10.1016/j.colsurfb.2015.01.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 01/07/2015] [Accepted: 01/08/2015] [Indexed: 11/25/2022]
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27
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Parker JA, Mattos C. The Ras-Membrane Interface: Isoform-specific Differences in The Catalytic Domain. Mol Cancer Res 2015; 13:595-603. [PMID: 25566993 DOI: 10.1158/1541-7786.mcr-14-0535] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 12/11/2014] [Indexed: 11/16/2022]
Abstract
The small GTPase Ras is mutated in about 20% of human cancers, primarily at active site amino acid residues G12, G13, and Q61. Thus, structural biology research has focused on the active site, impairment of GTP hydrolysis by oncogenic mutants, and characterization of protein-protein interactions in the effector lobe half of the protein. The C-terminal hypervariable region has increasingly gained attention due to its importance in H-Ras, N-Ras, and K-Ras differences in membrane association. A high-resolution molecular view of the Ras-membrane interaction involving the allosteric lobe of the catalytic domain has lagged behind, although evidence suggests that it contributes to isoform specificity. The allosteric lobe has recently gained interest for harboring potential sites for more selective targeting of this elusive "undruggable" protein. The present review reveals critical insight that isoform-specific differences appear prominently at these potentially targetable sites and integrates these differences with knowledge of Ras plasma membrane localization, with the intent to better understand the structure-function relationships needed to design isoform-specific Ras inhibitors.
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Affiliation(s)
- Jillian A Parker
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts
| | - Carla Mattos
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts.
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Khitrin A, Khitrin K, Model M. A model for membrane potential and intracellular ion distribution. Chem Phys Lipids 2014; 184:76-81. [DOI: 10.1016/j.chemphyslip.2014.10.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 10/27/2014] [Accepted: 10/31/2014] [Indexed: 10/24/2022]
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29
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Slavchov RI, Nomura T, Martinac B, Sokabe M, Sachs F. Gigaseal mechanics: creep of the gigaseal under the action of pressure, adhesion, and voltage. J Phys Chem B 2014; 118:12660-72. [PMID: 25295693 PMCID: PMC4226309 DOI: 10.1021/jp506965v] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Revised: 10/06/2014] [Indexed: 11/28/2022]
Abstract
Patch clamping depends on a tight seal between the cell membrane and the glass of the pipet. Why does the seal have such high electric resistance? Why does the patch adhere so strongly to the glass? Even under the action of strong hydrostatic, adhesion, and electrical forces, it creeps at a very low velocity. To explore possible explanations, we examined two physical models for the structure of the seal zone and the adhesion forces and two respective mechanisms of patch creep and electric conductivity. There is saline between the membrane and glass in the seal, and the flow of this solution under hydrostatic pressure or electroosmosis should drag a patch. There is a second possibility: the lipid core of the membrane is liquid and should be able to flow, with the inner monolayer slipping over the outer one. Both mechanisms predict the creep velocity as a function of the properties of the seal and the membrane, the pipet geometry, and the driving force. These model predictions are compared with experimental data for azolectin liposomes with added cholesterol or proteins. It turns out that to obtain experimentally observed creep velocities, a simple viscous flow in the seal zone requires ~10 Pa·s viscosity; it is unclear what structure might provide that because that viscosity alone severely constrains the electric resistance of the gigaseal. Possibly, it is the fluid bilayer that allows the motion. The two models provide an estimate of the adhesion energy of the membrane to the glass and membrane's electric characteristics through the comparison between the velocities of pressure-, adhesion-, and voltage-driven creep.
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Affiliation(s)
- Radomir I Slavchov
- Sofia University , Department of Physical Chemistry, 1 J. Bourchier Blvd., Sofia 1164, Bulgaria
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Bohinc K, Giner-Casares JJ, May S. Analytic Model for the Dipole Potential of a Lipid Layer. J Phys Chem B 2014; 118:7568-7576. [PMID: 24912019 DOI: 10.1021/jp5050173] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The larger permeability of anions than cations through a lipid bilayer can be rationalized by the positive sign of the bilayer's dipole potential. That is, upon crossing the lipid headgroups toward the hydrocarbon chain region, the electrostatic potential increases by several hundred millivolts. We derive an analytic expression for the dipole potential of a single lipid layer using an electrostatic model that is based on an extended version of the linearized Poisson-Boltzmann theory. The model highlights the ability of the lipid headgroups to render the dipole potential positive by inducing an orientational ordering of the solvent molecules. The positive contribution of the solvent overcompensates the negative dipole potential due to the bare lipids. Our theoretical prediction compares accurately with measurements of the dipole potential that we have conducted for mixed anionic-zwitterionic lipid monolayers at the air-water interface.
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Affiliation(s)
- Klemen Bohinc
- Faculty of Health Sciences, University of Ljubljana , Zdravstvena 5, SI-1000 Ljubljana, Slovenia
| | - Juan J Giner-Casares
- BioNanoPlasmonics Lab, CIC biomaGUNE , 20009 Donostia - San Sebastian, Spain.,Department of Physical Chemistry and Applied Thermodynamics, University of Cordoba , Campus de Rabanales, Edificio Marie Curie, Cordoba E-14014, Spain
| | - Sylvio May
- Department of Physics, North Dakota State University , Fargo, North Dakota 58108-6050, United States
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31
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Zhou S. Effects of discreteness of surface charges on the effective electrostatic interactions. J Chem Phys 2014; 140:234704. [PMID: 24952557 DOI: 10.1063/1.4881601] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- Shiqi Zhou
- School of Physics and Electronics, Central South University, Changsha, Hunan 410083, China
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32
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Schade M, Berti D, Huster D, Herrmann A, Arbuzova A. Lipophilic nucleic acids--a flexible construction kit for organization and functionalization of surfaces. Adv Colloid Interface Sci 2014; 208:235-51. [PMID: 24650567 DOI: 10.1016/j.cis.2014.02.019] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 02/26/2014] [Accepted: 02/26/2014] [Indexed: 11/19/2022]
Abstract
Lipophilic nucleic acids have become a versatile tool for structuring and functionalization of lipid bilayers and biological membranes as well as cargo vehicles to transport and deliver bioactive compounds, like interference RNA, into cells by taking advantage of reversible hybridization with complementary strands. This contribution reviews the different types of conjugates of lipophilic nucleic acids, and their physicochemical and self-assembly properties. Strategies for choosing a nucleic acid, lipophilic modification, and linker are discussed. Interaction with lipid membranes and its stability, dynamic structure and assembly of lipophilic nucleic acids upon embedding into biological membranes are specific points of the review. A large diversity of conjugates including lipophilic peptide nucleic acid and siRNA provides tailored solutions for specific applications in bio- and nanotechnology as well as in cell biology and medicine, as illustrated through some selected examples.
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Affiliation(s)
- Matthias Schade
- Humboldt-Universität zu Berlin, Institut für Biologie, Invalidenstr. 42, 10115 Berlin, Germany
| | - Debora Berti
- Dipartimento di Chimica, Universita' di Firenze & CSGI, Via della Lastruccia 3, 50019 Sesto Fiorentino, Firenze, Italy
| | - Daniel Huster
- Universität Leipzig, Institut für Medizinische Physik und Biophysik, Härtelstr. 16-18, 04107 Leipzig, Germany
| | - Andreas Herrmann
- Humboldt-Universität zu Berlin, Institut für Biologie, Invalidenstr. 42, 10115 Berlin, Germany
| | - Anna Arbuzova
- Humboldt-Universität zu Berlin, Institut für Biologie, Invalidenstr. 42, 10115 Berlin, Germany.
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33
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Henriksen JR, Etzerodt T, Gjetting T, Andresen TL. Side chain hydrophobicity modulates therapeutic activity and membrane selectivity of antimicrobial peptide mastoparan-X. PLoS One 2014; 9:e91007. [PMID: 24621994 PMCID: PMC3951324 DOI: 10.1371/journal.pone.0091007] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 02/07/2014] [Indexed: 11/29/2022] Open
Abstract
The discovery of new anti-infective compounds is stagnating and multi-resistant bacteria continue to emerge, threatening to end the “antibiotic era”. Antimicrobial peptides (AMPs) and lipo-peptides such as daptomycin offer themselves as a new potential class of antibiotics; however, further optimization is needed if AMPs are to find broad use as antibiotics. In the present work, eight analogues of mastoparan-X (MPX) were investigated, having side chain modifications in position 1, 8 and 14 to modulate peptide hydrophobicity. The self-association properties of the peptides were characterized, and the peptide-membrane interactions in model membranes were compared with the bactericidal and haemolytic properties. Alanine substitution at position 1 and 14 resulted in higher target selectivity (red blood cells versus bacteria), but also decreased bactericidal potency. For these analogues, the gain in target selectivity correlated to biophysical parameters showing an increased effective charge and reduction in the partitioning coefficient for membrane insertion. Introduction of an unnatural amino acid, with an octyl side chain by amino acid substitution, at positions 1, 8 and 14 resulted in increased bactericidal potency at the expense of radically reduced membrane target selectivity. Overall, optimized membrane selectivity or bactericidal potency was achieved by changes in side chain hydrophobicity of MPX. However, enhanced potency was achieved at the expense of selectivity and vice versa in all cases.
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Affiliation(s)
- Jonas R. Henriksen
- DTU Chemistry, Department of Chemistry, Technical University of Denmark, Center for Nanomedicine and Theranostics, Kongens Lyngby, Denmark
- * E-mail:
| | - Thomas Etzerodt
- DTU Nanotech, Department of Micro- and Nanotechnology, Technical University of Denmark, Center for Nanomedicine and Theranostics, Kongens Lyngby, Denmark
| | - Torben Gjetting
- DTU Nanotech, Department of Micro- and Nanotechnology, Technical University of Denmark, Center for Nanomedicine and Theranostics, Kongens Lyngby, Denmark
| | - Thomas L. Andresen
- DTU Nanotech, Department of Micro- and Nanotechnology, Technical University of Denmark, Center for Nanomedicine and Theranostics, Kongens Lyngby, Denmark
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34
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Binding of cationic pentapeptides with modified side chain lengths to negatively charged lipid membranes: Complex interplay of electrostatic and hydrophobic interactions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1818:1663-72. [PMID: 22433675 DOI: 10.1016/j.bbamem.2012.03.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Revised: 02/19/2012] [Accepted: 03/05/2012] [Indexed: 10/28/2022]
Abstract
Basic amino acids play a key role in the binding of membrane associated proteins to negatively charged membranes. However, side chains of basic amino acids like lysine do not only provide a positive charge, but also a flexible hydrocarbon spacer that enables hydrophobic interactions. We studied the influence of hydrophobic contributions to the binding by varying the side chain length of pentapeptides with ammonium groups starting with lysine to lysine analogs with shorter side chains, namely omithine (Orn), alpha, gamma-diaminobutyric acid (Dab) and alpha, beta-diaminopropionic acid (Dap). The binding to negatively charged phosphatidylglycerol (PG) membranes was investigated by calorimetry, FT-infrared spectroscopy (FT-IR) and monolayer techniques. The binding was influenced by counteracting and sometimes compensating contributions. The influence of the bound peptides on the lipid phase behavior depends on the length of the peptide side chains. Isothermal titration calorimetry (ITC) experiments showed exothermic and endothermic effects compensating to a different extent as a function of side chain length. The increase in lipid phase transition temperature was more significant for peptides with shorter side chains. FTIR-spectroscopy revealed changes in hydration of the lipid bilayer interface after peptide binding. Using monolayer techniques, the contributions of electrostatic and hydrophobic effects could clearly be observed. Peptides with short side chains induced a pronounced decrease in surface pressure of PG monolayers whereas peptides with additional hydrophobic interactions decreased the surface pressure much less or even lead to an increase, indicating insertion of the hydrophobic part of the side chain into the lipid monolayer.
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35
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Honigmann A, van den Bogaart G, Iraheta E, Risselada HJ, Milovanovic D, Mueller V, Müllar S, Diederichsen U, Fasshauer D, Grubmüller H, Hell SW, Eggeling C, Kühnel K, Jahn R. Phosphatidylinositol 4,5-bisphosphate clusters act as molecular beacons for vesicle recruitment. Nat Struct Mol Biol 2013; 20:679-86. [PMID: 23665582 PMCID: PMC3676452 DOI: 10.1038/nsmb.2570] [Citation(s) in RCA: 211] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 03/25/2013] [Indexed: 11/09/2022]
Abstract
Synaptic-vesicle exocytosis is mediated by the vesicular Ca(2+) sensor synaptotagmin-1. Synaptotagmin-1 interacts with the SNARE protein syntaxin-1A and acidic phospholipids such as phosphatidylinositol 4,5-bisphosphate (PIP2). However, it is unclear how these interactions contribute to triggering membrane fusion. Using PC12 cells from Rattus norvegicus and artificial supported bilayers, we show that synaptotagmin-1 interacts with the polybasic linker region of syntaxin-1A independent of Ca(2+) through PIP2. This interaction allows both Ca(2+)-binding sites of synaptotagmin-1 to bind to phosphatidylserine in the vesicle membrane upon Ca(2+) triggering. We determined the crystal structure of the C2B domain of synaptotagmin-1 bound to phosphoserine, allowing development of a high-resolution model of synaptotagmin bridging two different membranes. Our results suggest that PIP2 clusters organized by syntaxin-1 act as molecular beacons for vesicle docking, with the subsequent Ca(2+) influx bringing the vesicle membrane close enough for membrane fusion.
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Affiliation(s)
- Alf Honigmann
- Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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36
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Increased pH-sensitivity of protein binding to lipid membranes through the electrostatic-hydrogen bond switch. Chem Phys Lipids 2013; 169:9-18. [PMID: 23376429 DOI: 10.1016/j.chemphyslip.2013.01.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 12/24/2012] [Accepted: 01/21/2013] [Indexed: 01/23/2023]
Abstract
The signaling lipid phosphatidic acid (PA) is believed to interact specifically with membrane-bound globular proteins through a combination of electrostatic interactions and hydrogen bond formation known as the electrostatic-hydrogen bond switch. PA, which adjusts its protonation state according to the ambient pH, is able to regulate protein binding under physiological conditions in a pH-dependent manner. We investigate the question to what extent the electrostatic-hydrogen bond switch contributes to the pH-sensitivity of protein binding. To this end, we propose a theoretical model for the adsorption of a basic protein on a zwitterionic membrane that contains phosphatidic acid as a minor component. Our model is based on an extended continuum Poisson-Boltzmann approach that accounts for zwitterionic lipids, the protonation/deprotonation equilibrium of PA, and the lateral mobility of the lipids in the membrane. The electrostatic-hydrogen bond switch enters as an additional non-electrostatic attractive interaction of deprotonated PA with basic protein residues. For a generic model protein we calculate the adsorption free energy and its pH-dependence. Our results suggest that the electrostatic-hydrogen bond switch not only increases the affinity between PA and the protein but also its sensitivity with respect to changes in pH. That is, the electrostatic-hydrogen bond switch helps enabling the membrane to use physiological pH changes in order to trigger protein adsorption/desorption.
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37
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Dubovskii PV. Unusual titration of the membrane-bound artificial hemagglutinin fusion peptide. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2012; 41:1077-84. [DOI: 10.1007/s00249-012-0867-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Revised: 09/25/2012] [Accepted: 10/04/2012] [Indexed: 11/28/2022]
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38
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Boggs JM, Rangaraj G, Dicko A. Effect of phosphorylation of phosphatidylinositol on myelin basic protein-mediated binding of actin filaments to lipid bilayers in vitro. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:2217-27. [PMID: 22538354 DOI: 10.1016/j.bbamem.2012.04.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Accepted: 04/10/2012] [Indexed: 12/14/2022]
Abstract
Myelin basic protein (MBP) binds to negatively charged lipids on the cytosolic surface of oligodendrocytes and is believed to be responsible for adhesion of these surfaces in the multilayered myelin sheath. It can also assemble actin filaments and tether them to lipid bilayers through electrostatic interactions. Here we investigate the effect of increased negative charge of the lipid bilayer due to phosphorylation of phosphatidylinositol (PI) on MBP-mediated binding of actin to the lipid bilayer, by substituting phosphatidylinositol 4-phosphate or phosphatidylinositol 4,5-bisphosphate for PI in phosphatidylcholine/phosphatidylglycerol lipid vesicles. Phosphorylation of PI caused dissociation of the MBP/actin complex from the lipid vesicles due to repulsion of the negatively charged complex from the negatively charged membrane surface. An effect of phosphorylation could be detected even if the inositol lipid was only 2mol% of the total lipid. Calcium-calmodulin dissociated actin from the MBP-lipid vesicles and phosphorylation of PI increased the amount dissociated. These results show that changes to the lipid composition of myelin, which could occur during signaling or other physiological events, could regulate the ability of MBP to act as a scaffolding protein and bind actin filaments to the lipid bilayer.
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Affiliation(s)
- Joan M Boggs
- Hospital for Sick Children, Toronto, ON, Canada.
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39
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Martins PT, Velazquez-Campoy A, Vaz WLC, Cardoso RMS, Valério J, Moreno MJ. Kinetics and Thermodynamics of Chlorpromazine Interaction with Lipid Bilayers: Effect of Charge and Cholesterol. J Am Chem Soc 2012; 134:4184-95. [DOI: 10.1021/ja209917q] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Patrícia T. Martins
- Chemistry Department FCTUC, Largo D. Dinis, Rua Larga, 3004-535 Coimbra,
Portugal
| | - Adrian Velazquez-Campoy
- Institute of Biocomputation
and Physics of Complex Systems (BIFI), Universidad de Zaragoza, 50018 Zaragoza, Spain, Unidad Asociada BIFI-IQFR,
CSIC, Zaragoza, Spain
- Fundación ARAID, Diputación General de Aragón, Spain
| | - Winchil L. C. Vaz
- Chemistry Department FCTUC, Largo D. Dinis, Rua Larga, 3004-535 Coimbra,
Portugal
| | - Renato M. S. Cardoso
- Chemistry Department FCTUC, Largo D. Dinis, Rua Larga, 3004-535 Coimbra,
Portugal
| | - Joana Valério
- Instituto de Tecnologia Química e Biológica − UNL, Av.
da República-EAN, 2780-157 Oeiras, Portugal
| | - Maria João Moreno
- Chemistry Department FCTUC, Largo D. Dinis, Rua Larga, 3004-535 Coimbra,
Portugal
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40
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Kiselev VY, Leda M, Lobanov AI, Marenduzzo D, Goryachev AB. Lateral dynamics of charged lipids and peripheral proteins in spatially heterogeneous membranes: comparison of continuous and Monte Carlo approaches. J Chem Phys 2012; 135:155103. [PMID: 22029337 DOI: 10.1063/1.3652958] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Biological membranes are complex environments whose physico-chemical properties are of utmost importance for the understanding of many crucial biological processes. Much attention has been given in the literature to the description of membranes along the z-axis perpendicular to the membrane. Here, we instead consider the lateral dynamics of lipids and peripheral proteins due to their electrostatic interaction. Previously, we constructed a Monte Carlo automaton capable of simulating mutual diffusive dynamics of charged lipids and associated positively charged peptides. Here, we derive and numerically analyze a system of Poisson-Boltzmann-Nernst-Planck (PBNP) equations that provide a mean-field approximation compatible with our Monte Carlo model. The thorough comparison between the mean-field PBNP equations and Monte Carlo simulations demonstrates that both the approaches are in a good qualitative agreement in all tested scenarios. We find that the two methods quantitatively deviate when the local charge density is high, presumably because the Poisson-Boltzmann formalism is applicable in the so-called weak coupling limit, whose validity is restricted to low charge densities. Nevertheless, we conclude that the mean-field PBNP approach provides a good approximation for the considerably more detailed Monte Carlo model at only a fraction of the associated computational cost and allows simulation of the membrane lateral dynamics on the space and time scales relevant for the realistic biological problems.
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Affiliation(s)
- Vladimir Yu Kiselev
- Centre for Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom
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41
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Bouaouina M, Goult BT, Huet-Calderwood C, Bate N, Brahme NN, Barsukov IL, Critchley DR, Calderwood DA. A conserved lipid-binding loop in the kindlin FERM F1 domain is required for kindlin-mediated αIIbβ3 integrin coactivation. J Biol Chem 2012; 287:6979-90. [PMID: 22235127 DOI: 10.1074/jbc.m111.330845] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The activation of heterodimeric integrin adhesion receptors from low to high affinity states occurs in response to intracellular signals that act on the short cytoplasmic tails of integrin β subunits. Binding of the talin FERM (four-point-one, ezrin, radixin, moesin) domain to the integrin β tail provides one key activation signal, but recent data indicate that the kindlin family of FERM domain proteins also play a central role. Kindlins directly bind integrin β subunit cytoplasmic domains at a site distinct from the talin-binding site, and target to focal adhesions in adherent cells. However, the mechanisms by which kindlins impact integrin activation remain largely unknown. A notable feature of kindlins is their similarity to the integrin-binding and activating talin FERM domain. Drawing on this similarity, here we report the identification of an unstructured insert in the kindlin F1 FERM domain, and provide evidence that a highly conserved polylysine motif in this loop supports binding to negatively charged phospholipid head groups. We further show that the F1 loop and its membrane-binding motif are required for kindlin-1 targeting to focal adhesions, and for the cooperation between kindlin-1 and -2 and the talin head in αIIbβ3 integrin activation, but not for kindlin binding to integrin β tails. These studies highlight the structural and functional similarities between kindlins and the talin head and indicate that as for talin, FERM domain interactions with acidic membrane phospholipids as well β-integrin tails contribute to the ability of kindlins to activate integrins.
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Affiliation(s)
- Mohamed Bouaouina
- Department of Pharmacology and Cell Biology and Interdepartmental Program in Vascular Biology and Therapeutics, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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Ibl V, Csaszar E, Schlager N, Neubert S, Spitzer C, Hauser MT. Interactome of the plant-specific ESCRT-III component AtVPS2.2 in Arabidopsis thaliana. J Proteome Res 2011; 11:397-411. [PMID: 22010978 PMCID: PMC3252797 DOI: 10.1021/pr200845n] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
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The endosomal sorting complexes required for transport (ESCRT) guides transmembrane proteins to domains that bud away from the cytoplasm. The ESCRT machinery consists of four complexes. ESCRT complexes 0–II are important for cargo recognition and concentration via ubiquitin binding. Most of the membrane bending function is mediated by the large multimeric ESCRT-III complex and associated proteins. Here we present the first in vivo proteome analysis of a member of the ESCRT-III complex which is unique to the plant kingdom. We show with LC–MS/MS, yeast-two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) that coimmunoprecipitated proteins from Arabidopsisthaliana roots expressing a functional GFP-tagged VACUOLAR PROTEIN SORTING 2.2 (AtVPS2.2) protein are members of the ESCRT-III complex and associated proteins. Therefore we propose that at least in plants the large ESCRT-III membrane scaffolding complex consists of a mixture of SNF7, VPS2 and the associated VPS46 and VPS60 proteins. Apart from transmembrane proteins, numerous membrane-associated but also nuclear and extracellular proteins have been identified, indicating that AtVPS2.2 might be involved in processes beyond the classical ESCRT role. This study is the first in vivo proteome analysis with a tagged ESCRT-III component demonstrating the feasibility of this approach and provides numerous starting points for the investigation of the biological process in which AtVPS2.2 is involved. The endosomal sorting complexes required for transport (ESCRT) guides transmembrane proteins to domains that bud away from the cytoplasm. Most of the membrane bending function is mediated by the ESCRT-III complex. Proteomic analysis was used to identify novel ESCRT-III interactors of Arabidopsis thaliana seedlings expressing a functional GFP-tagged VACUOLAR PROTEIN SORTING2.2 as bait. Some intractors were confirmed by yeast-two-hybrid and bimolecular fluorescence complementation and others will be the target for future investigations.
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Affiliation(s)
- Verena Ibl
- Department of Applied Genetics and Cell Biology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
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43
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Wilke N, Maggio B. Electrostatic field effects on membrane domain segregation and on lateral diffusion. Biophys Rev 2011; 3:185-192. [PMID: 28510045 DOI: 10.1007/s12551-011-0057-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 08/20/2011] [Indexed: 12/17/2022] Open
Abstract
Natural membranes are organized structures of neutral and charged molecules bearing dipole moments which generate local non-homogeneous electric fields. When subjected to such fields, the molecules experience net forces that can modify the lipid and protein organization, thus modulating cell activities and influencing (or even dominating) the biological functions. The energetics of electrostatic interactions in membranes is a long-range effect which can vary over distance within r-1 to r-3. In the case of a dipole interacting with a plane of dipoles, e.g. a protein interacting with a lipid domain, the interaction is stronger than two punctual dipoles and depends on the size of the domain. In this article, we review several contributions on how electrostatic interactions in the membrane plane can modulate the phase behavior, surface topography and mechanical properties in monolayers and bilayers.
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Affiliation(s)
- Natalia Wilke
- Centro de Investigaciones de Química Bológica de Córdoba (CIQUIBIC-CONICET), Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina. .,CIQUIBIC, Dpto. de Química Biológica, Fac. de Cs. Químicas, UNC, Pabellón Argentina, Ciudad Universitaria, X5000HUA, Córdoba, Argentina.
| | - Bruno Maggio
- Centro de Investigaciones de Química Bológica de Córdoba (CIQUIBIC-CONICET), Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
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44
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Kiselev VY, Marenduzzo D, Goryachev AB. Lateral dynamics of proteins with polybasic domain on anionic membranes: a dynamic Monte-Carlo study. Biophys J 2011; 100:1261-70. [PMID: 21354399 DOI: 10.1016/j.bpj.2011.01.025] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Accepted: 01/13/2011] [Indexed: 10/18/2022] Open
Abstract
Positively charged polybasic domains are essential for recruiting multiple signaling proteins, such as Ras GTPases and Src kinase, to the negatively charged cellular membranes. Much less, however, is known about the influence of electrostatic interactions on the lateral dynamics of these proteins. We developed a dynamic Monte-Carlo automaton that faithfully simulates lateral diffusion of the adsorbed positively charged oligopeptides as well as the dynamics of mono- (phosphatidylserine) and polyvalent (PIP(2)) anionic lipids within the bilayer. In agreement with earlier results, our simulations reveal lipid demixing that leads to the formation of a lipid shell associated with the peptide. The computed association times and average numbers of bound lipids demonstrate that tetravalent PIP(2) interacts with the peptide much more strongly than monovalent lipid. On the spatially homogeneous membrane, the lipid shell affects the behavior of the peptide only by weakly reducing its lateral mobility. However, spatially heterogeneous distributions of monovalent lipids are found to produce peptide drift, the velocity of which is determined by the total charge of the peptide-lipid complex. We hypothesize that this predicted phenomenon may affect the spatial distribution of proteins with polybasic domains in the context of cell-signaling events that alter the local density of monovalent anionic lipids.
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Affiliation(s)
- Vladimir Yu Kiselev
- Centre for Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
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45
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Effects of curvature and composition on α-synuclein binding to lipid vesicles. Biophys J 2011; 99:2279-88. [PMID: 20923663 DOI: 10.1016/j.bpj.2010.07.056] [Citation(s) in RCA: 300] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 07/23/2010] [Accepted: 07/26/2010] [Indexed: 11/21/2022] Open
Abstract
Parkinson's disease is characterized by the presence of intracellular aggregates composed primarily of the neuronal protein α-synuclein (αS). Interactions between αS and various cellular membranes are thought to be important to its native function as well as relevant to its role in disease. We use fluorescence correlation spectroscopy to investigate binding of αS to lipid vesicles as a function of the lipid composition and membrane curvature. We determine how these parameters affect the molar partition coefficient of αS, providing a quantitative measure of the binding energy, and calculate the number of lipids required to bind a single protein. Specific anionic lipids have a large effect on the free energy of binding. Lipid chain saturation influences the binding interaction to a lesser extent, with larger partition coefficients measured for gel-phase vesicles than for fluid-phase vesicles, even in the absence of anionic lipid components. Although we observe variability in the binding of the mutant proteins, differences in the free energies of partitioning are less dramatic than with varied lipid compositions. Vesicle curvature has a strong effect on the binding affinity, with a >15-fold increase in affinity for small unilamellar vesicles over large unilamellar vesicles, suggesting that αS may be a curvature-sensing protein. Our findings provide insight into how physical properties of the membrane may modulate interactions of αS with cellular membranes.
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46
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Abstract
The ability to predict properties such as peptide binding and insertion into membranes is an important and time-saving asset in the design of new cell-penetrating peptides (CPPs). Methods to predict those properties are described here, which make use of calculations performed with the Wimley-White hydrophobicity scales. In addition, electrostatic effects can be estimated in a way that provides acceptably close approximations in many cases. Finally, an estimate of the probability of insertion is also discussed. These procedures are illustrated by comparing the calculations with experiments on a few CPPs.
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Affiliation(s)
- Paulo F Almeida
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, NC, USA
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47
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Alonso S, Bär M. Phase separation and bistability in a three-dimensional model for protein domain formation at biomembranes. Phys Biol 2010; 7:046012. [PMID: 21149929 DOI: 10.1088/1478-3975/7/4/046012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Proteins in living cells interact with membranes. They may bind to or unbind from the membrane to the cytosol depending on the lipid composition of the membrane and their interaction with cytosolic enzymes. Moreover, proteins can accumulate at the membrane and assemble in spatial domains. Here, a simple model of protein cycling at biomembranes is studied, when the total number of proteins is conserved. Specifically, we consider the spatio-temporal dynamics of MARCKS proteins and their interactions with enzymes facilitating translocation from and rebinding to the membrane. The model exhibits two qualitatively different mechanisms of protein domain formation: phase separation related to a long-wave instability of a membrane state with homogeneous protein coverage and stable coexistence of two states with different homogeneous protein coverage in bistable media. We evaluate the impact of the cytosolic volume on the occurrence of protein pattern formation by simulations in a three-dimensional model. We show that the explicit treatment of the volume in the model leads to an effective rescaling of the reaction rates. For a simplified model of protein cycling, we can derive analytical expressions for the rescaling coefficients and verify them by direct simulations with the complete three-dimensional model.
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Affiliation(s)
- Sergio Alonso
- Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, 10587 Berlin, Germany.
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Callenberg KM, Choudhary OP, de Forest GL, Gohara DW, Baker NA, Grabe M. APBSmem: a graphical interface for electrostatic calculations at the membrane. PLoS One 2010; 5:e12722. [PMID: 20949122 PMCID: PMC2947494 DOI: 10.1371/journal.pone.0012722] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Accepted: 08/18/2010] [Indexed: 02/07/2023] Open
Abstract
Electrostatic forces are one of the primary determinants of molecular interactions. They help guide the folding of proteins, increase the binding of one protein to another and facilitate protein-DNA and protein-ligand binding. A popular method for computing the electrostatic properties of biological systems is to numerically solve the Poisson-Boltzmann (PB) equation, and there are several easy-to-use software packages available that solve the PB equation for soluble proteins. Here we present a freely available program, called APBSmem, for carrying out these calculations in the presence of a membrane. The Adaptive Poisson-Boltzmann Solver (APBS) is used as a back-end for solving the PB equation, and a Java-based graphical user interface (GUI) coordinates a set of routines that introduce the influence of the membrane, determine its placement relative to the protein, and set the membrane potential. The software Jmol is embedded in the GUI to visualize the protein inserted in the membrane before the calculation and the electrostatic potential after completing the computation. We expect that the ease with which the GUI allows one to carry out these calculations will make this software a useful resource for experimenters and computational researchers alike. Three examples of membrane protein electrostatic calculations are carried out to illustrate how to use APBSmem and to highlight the different quantities of interest that can be calculated.
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Affiliation(s)
- Keith M. Callenberg
- Carnegie Mellon-University of Pittsburgh Program in Computational Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Om P. Choudhary
- Carnegie Mellon-University of Pittsburgh Program in Computational Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Gabriel L. de Forest
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - David W. Gohara
- The Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University, St. Louis, Missouri, United States of America
| | - Nathan A. Baker
- Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Michael Grabe
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
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Homchaudhuri L, Polverini E, Gao W, Harauz G, Boggs JM. Influence of membrane surface charge and post-translational modifications to myelin basic protein on its ability to tether the Fyn-SH3 domain to a membrane in vitro. Biochemistry 2010; 48:2385-93. [PMID: 19178193 DOI: 10.1021/bi8022587] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Myelin basic protein (MBP) is a highly post-translationally modified, multifunctional structural component of central nervous system myelin, adhering to phospholipid membranes and assembling cytoskeletal proteins, and has previously been shown to bind SH3 domains in vitro and tether them to a membrane surface [Polverini, E., et al. (2008) Biochemistry 47, 267-282]. Since molecular modeling shows that the Fyn-SH3 domain has a negative surface charge density even after binding the MBP ligand, we have investigated the influence of negative membrane surface charge and the effects of post-translational modifications to MBP on the interaction of the Fyn-SH3 domain with membrane-associated MBP. Using a sedimentation assay with multilamellar vesicles consisting of neutral phosphatidylcholine (PC) and negatively charged phosphatidylinositol (PI), we demonstrate that increasing the negative surface charge of the membrane by increasing the proportion of PI reduces the amount of Fyn-SH3 domain that binds to membrane-associated MBP, due to electrostatic repulsion. When one of the phosphoinositides, PI(4)P or PI(4,5)P(2) was substituted for PI in equal proportion, none of the Fyn-SH3 domain bound to MBP under the conditions that were used. Post-translational modifications of MBP which reduced its net positive charge, i.e., phosphorylation or arginine deimination, increased the degree of repulsion of Fyn-SH3 from the membrane surface, an effect further modulated by the lipid charge. This study suggests that changes in membrane negative surface charge due to protein or lipid modifications, which could occur during cell signaling, can regulate the binding of the Fyn-SH3 domain to membrane-associated MBP and thus could regulate the activity of Fyn at the oligodendrocyte membrane surface.
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Affiliation(s)
- Lopamudra Homchaudhuri
- Department of Molecular Structure and Function, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
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Alves-Silva J, Ribeiro JMC, Abbeele JVD, Attardo G, Hao Z, Haines LR, Soares MB, Berriman M, Aksoy S, Lehane MJ. An insight into the sialome of Glossina morsitans morsitans. BMC Genomics 2010; 11:213. [PMID: 20353571 PMCID: PMC2853526 DOI: 10.1186/1471-2164-11-213] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Accepted: 03/30/2010] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Blood feeding evolved independently in worms, arthropods and mammals. Among the adaptations to this peculiar diet, these animals developed an armament of salivary molecules that disarm their host's anti-bleeding defenses (hemostasis), inflammatory and immune reactions. Recent sialotranscriptome analyses (from the Greek sialo = saliva) of blood feeding insects and ticks have revealed that the saliva contains hundreds of polypeptides, many unique to their genus or family. Adult tsetse flies feed exclusively on vertebrate blood and are important vectors of human and animal diseases. Thus far, only limited information exists regarding the Glossina sialome, or any other fly belonging to the Hippoboscidae. RESULTS As part of the effort to sequence the genome of Glossina morsitans morsitans, several organ specific, high quality normalized cDNA libraries have been constructed, from which over 20,000 ESTs from an adult salivary gland library were sequenced. These ESTs have been assembled using previously described ESTs from the fat body and midgut libraries of the same fly, thus totaling 62,251 ESTs, which have been assembled into 16,743 clusters (8,506 of which had one or more EST from the salivary gland library). Coding sequences were obtained for 2,509 novel proteins, 1,792 of which had at least one EST expressed in the salivary glands. Despite library normalization, 59 transcripts were overrepresented in the salivary library indicating high levels of expression. This work presents a detailed analysis of the salivary protein families identified. Protein expression was confirmed by 2D gel electrophoresis, enzymatic digestion and mass spectrometry. Concurrently, an initial attempt to determine the immunogenic properties of selected salivary proteins was undertaken. CONCLUSIONS The sialome of G. m. morsitans contains over 250 proteins that are possibly associated with blood feeding. This set includes alleles of previously described gene products, reveals new evidence that several salivary proteins are multigenic and identifies at least seven new polypeptide families unique to Glossina. Most of these proteins have no known function and thus, provide a discovery platform for the identification of novel pharmacologically active compounds, innovative vector-based vaccine targets, and immunological markers of vector exposure.
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Affiliation(s)
- Juliana Alves-Silva
- Vector Group, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
- Current address: The Healing Foundation Centre, Manchester, M13 9PT, UK
| | - José MC Ribeiro
- Section of Vector Biology, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, Rockville MD 20852, USA
| | - Jan Van Den Abbeele
- Department of Parasitology, Unit of Entomology, Institute of Tropical Medicine, B-2000 Antwerp, Belgium
| | - Geoffrey Attardo
- Department of Epidemiology of Microbial Diseases, Yale School of Public Heath, New Haven, CT 06520, USA
| | - Zhengrong Hao
- Department of Epidemiology of Microbial Diseases, Yale School of Public Heath, New Haven, CT 06520, USA
| | - Lee R Haines
- Vector Group, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Marcelo B Soares
- Children's Memorial Research Center, North-Western University, Chicago, IL 60614, USA
| | | | - Serap Aksoy
- Department of Epidemiology of Microbial Diseases, Yale School of Public Heath, New Haven, CT 06520, USA
| | - Michael J Lehane
- Vector Group, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
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