Topography of diphtheria toxin A chain inserted into lipid vesicles.
AuthorsHayashibara M, London E
JournalBiochemistry
PubMed ID15697244
'The membrane-inserting T domain of diphtheria toxin aids the low-pH-triggered translocation of the catalytic A chain of the toxin across endosomal membranes. To evaluate the role of the isolated A chain in translocation, the topography of isolated A chain inserted into model membrane vesicles was investigated using a mixture either ... More
pH- and ionic strength-dependent fusion of phospholipid vesicles induced by pardaxin analogues or by mixtures of charge-reversed peptides.
AuthorsRapaport D, Hague GR, Pouny Y, Shai Y
JournalBiochemistry
PubMed ID8461295
'The fusogenic properties of the neurotoxin paradaxin and eight of its analogues with small unilamellar vesicles (SUV), composed of egg phosphatidylcholine and phosphatidylserine (PC/PS), were investigated. Fusion was demonstrated by a lipid-mixing assay and by an increase in vesicle size as revealed by electron microscopy. The lipid-mixing assay was performed ... More
Measurement of thermodynamic parameters for hydrophobic mismatch 2: intermembrane transfer of a transmembrane helix.
AuthorsYano Y, Ogura M, Matsuzaki K
JournalBiochemistry
PubMed ID16519532
'Hydrophobic matching between proteins and lipids is essential for the thermodynamic stability of integral membrane proteins. However, there is no direct thermodynamic information available about the intermembrane transfer of proteins between membranes with different hydrophobic thicknesses, which is crucial for understanding hydrophobic mismatch. This article reports the complete set of ... More
Does cholesterol discriminate between sphingomyelin and phosphatidylcholine in mixed monolayers containing both phospholipids?
AuthorsMattjus P, Slotte JP
JournalChem Phys Lipids
PubMed ID9450320
'The objective of this work was to examine the interaction of cholesterol with both phosphatidylcholines, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) or 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), and sphingomyelins, N-oleoyl-D-sphingomyelin (O-SPM) or N-palmitoyl-D-sphingomyelin (P-SPM), in monolayers at an air/water interface. We used cholesterol oxidase to probe for the relative strength of sterol-phospholipid interaction, and fluorescence microscopy to ... More
Effect of nonpolar substitutions of the conserved Phe11 in the fusion peptide of HIV-1 gp41 on its function, structure, and organization in membranes.
AuthorsPritsker M, Rucker J, Hoffman TL, Doms RW, Shai Y
JournalBiochemistry
PubMed ID10471286
'The fusion domain of the HIV-1 envelope glycoprotein (gp120-gp41) is a conserved hydrophobic region located at the N-terminus of the transmembrane subunit (gp41). A prominent feature of this domain is a conserved five-residue "FLGFL" sequence at positions 8-12. Mutation of the highly conserved Phe(11) to Val (F11V), presumed not to ... More
Novel Fusogenic Liposomes for Fluorescent Cell Labeling and Membrane Modification.
AuthorsCsisza´r A, Hersch N, Dieluweit S, Biehl R, Merkel R, Hoffmann B,
JournalBioconjug Chem
PubMed ID20184308
'Efficient delivery of biomolecules into membranes of living cells as well as cell surface modifications are major biotechnological challenges. Here, novel liposome systems based on neutral and cationic lipids in combination with lipids modified by aromatic groups are introduced for such applications. The fusion efficiency of these liposome systems was ... More
Cellular retention of liposome-delivered anionic compounds modulated by a probenecid-sensitive anion transporter.
AuthorsOh YK, Straubinger RM
JournalPharm Res
PubMed ID9327449
'PURPOSE: Drug carriers such as liposomes may enhance the intracellular delivery of therapeutic agents for infectious or neoplastic diseases. However, the mechanisms affecting cellular retention of liposome contents are understood poorly. We tested the hypothesis that retention of anionic compounds may be modulated by a nonspecific probenecid-sensitive anion transport mechanism, ... More
An apolipoprotein E-derived peptide mediates uptake of sterically stabilized liposomes into brain capillary endothelial cells.
AuthorsSauer I, Dunay IR, Weisgraber K, Bienert M, Dathe M
JournalBiochemistry
PubMed ID15697227
'A promising strategy to solve the problems of insufficient membrane penetration of drugs and low target specificity is the localization of targeting and uptake-facilitating ligands on the surface of drug-carrier systems. This study investigated the role of a peptide derived from the LDL receptor (LDLr)-binding domain of apolipoprotein E (apoE) ... More
Organized arrays of individual DNA molecules tethered to supported lipid bilayers.
AuthorsGranéli A, Yeykal CC, Prasad TK, Greene EC
JournalLangmuir
PubMed ID16378434
'An unappreciated aspect of many single-molecule techniques is the need for an inert surface to which individual molecules can be anchored without compromising their biological integrity. Here, we present new methods for tethering large DNA molecules to the surface of a microfluidic sample chamber that has been rendered inert by ... More
Simultaneous measurement of spectroscopic and physiological signals from a planar bilayer system: detecting voltage-dependent movement of a membrane-incorporated peptide.
AuthorsHanyu Y, Yamada T, Matsumoto G
JournalBiochemistry
PubMed ID9799498
'We developed an experimental system that can measure spectroscopic and physiological signals simultaneously from ion channels in a planar lipid bilayer, to study the relationship between the structure and function of the ion channels. While the membrane potential was clamped, fluorescent emission and ionic currents were measured simultaneously. The fluorescent ... More
Identification of protein kinase C isozymes responsible for the phosphorylation of photoreceptor-specific RGS9-1 at Ser475.
AuthorsSokal I, Hu G, Liang Y, Mao M, Wensel TG, Palczewski K,
JournalJ Biol Chem
PubMed ID12499365
'Inactivation of the visual G-protein transducin by GTP hydrolysis is regulated by the GTPase-accelerating protein (GAP) RGS9-1. Regulation of RGS9-1 itself is poorly understood, but we found previously that it is subject to a light- and Ca(2+)-sensitive phosphorylation on Ser(475). Because there are much higher RGS9-1 levels in cones than ... More
Lipid domains and lipid/protein interactions in biological membranes.
AuthorsTocanne JF, Cézanne L, Lopez A, Piknova B, Schram V, Tournier JF, Welby M
JournalChem Phys Lipids
PubMed ID8001179
'In the fluid mosaic model of membranes, lipids are organized in the form of a bilayer supporting peripheral and integral proteins. This model considers the lipid bilayer as a two-dimensional fluid in which lipids and proteins are free to diffuse. As a direct consequence, both types of molecules would be ... More
Fluorescently labelled Na+ channels are localized and immobilized to synapses of innervated muscle fibres.
AuthorsAngelides KJ
JournalNature
PubMed ID2422557
'Segregation of voltage-dependent sodium channels to the hillock of motoneurones and nodes of Ranvier in myelinated axons is crucial for conduction of the nerve impulse. Much less is known, however, about the distribution of voltage-dependent Na+ channels on muscle fibres. Recently, Beam et al. have shown that Na+ channels are ... More
Distribution and lateral mobility of voltage-dependent sodium channels in neurons.
AuthorsAngelides KJ, Elmer LW, Loftus D, Elson E
JournalJ Cell Biol
PubMed ID2454930
'Voltage-dependent sodium channels are distributed nonuniformly over the surface of nerve cells and are localized to morphologically distinct regions. Fluorescent neurotoxin probes specific for the voltage-dependent sodium channel stain the axon hillock 5-10 times more intensely than the cell body and show punctate fluorescence confined to the axon hillock which ... More
Suppressing Brownian motion of individual biomolecules in solution.
AuthorsCohen AE, Moerner WE
JournalProc Natl Acad Sci U S A
PubMed ID16537418
'Single biomolecules in free solution have long been of interest for detailed study by optical methods, but Brownian motion prevents the observation of one single molecule for extended periods. We have used an anti-Brownian electrokinetic (ABEL) trap to trap individual protein molecules in free solution, under ambient conditions, without requiring ... More
Membrane asymmetry in epithelia: is the tight junction a barrier to diffusion in the plasma membrane?
AuthorsDragsten PR, Blumenthal R, Handler JS
JournalNature
PubMed ID7322203
Free brownian motion of individual lipid molecules in biomembranes
AuthorsSonnleitner A, Schutz GJ, Schmidt T
JournalBiophys J
PubMed ID10545363
The mobility of phospolipids in free-standing and supported membranes was investigated on the level of individual molecules. For the analysis of trajectories a new statistical treatment was developed that permitted us to clearly distinguish different types of diffusional motion. A freely diffusing subfraction of lipids within supported membranes was identified. ... More
Islet amyloid polypeptide-induced membrane leakage involves uptake of lipids by forming amyloid fibers.
AuthorsSparr E, Engel MF, Sakharov DV, Sprong M, Jacobs J, de Kruijff B, Höppener JW, Killian JA
JournalFEBS Lett
PubMed ID15527771
Fibril formation of islet amyloid polypeptide (IAPP) is associated with cell death of the insulin-producing pancreatic beta-cells in patients with Type 2 Diabetes Mellitus. A likely cause for the cytotoxicity of human IAPP is that it destroys the barrier properties of the cell membrane. Here, we show by fluorescence confocal ... More
Coordination between the actin cytoskeleton and membrane deformation by a novel membrane tubulation domain of PCH proteins is involved in endocytosis.
AuthorsTsujita K, Suetsugu S, Sasaki N, Furutani M, Oikawa T, Takenawa T,
JournalJ Cell Biol
PubMed ID16418535
The conserved FER-CIP4 homology (FCH) domain is found in the pombe Cdc15 homology (PCH) protein family members, including formin-binding protein 17 (FBP17). However, the amino acid sequence homology extends beyond the FCH domain. We have termed this region the extended FC (EFC) domain. We found that FBP17 coordinated membrane deformation ... More
Evaluation of a high-content screening fluorescence-based assay analyzing the pharmacological modulation of lipid homeostasis in human macrophages.
AuthorsWerner T, Liebisch G, Grandl M, Schmitz G
JournalCytometry A
PubMed ID16496419
BACKGROUND: For understanding cholesterol and phospholipid efflux pathways there is a need for cellular fluorescence-based high-content screens (HCS) to investigated the cholesterol and phospholipid content in human macrophages. METHODS: Making use of fluorescence imaging based on HCS we have developed a tool to evaluate new agents that can act as ... More
The domains of a cholesterol-dependent cytolysin undergo a major FRET-detected rearrangement during pore formation.
AuthorsRamachandran R, Tweten RK, Johnson AE
JournalProc Natl Acad Sci U S A
PubMed ID15878993
FRET measurements were used to determine the domain-specific topography of perfringolysin O, a pore-forming toxin, on a membrane surface at different stages of pore formation. The data reveal that the elongated toxin monomer binds stably to the membrane in an "end-on" orientation, with its long axis approximately perpendicular to the ... More
N-NBD-L-alpha-dilauroylphosphatidylethanolamine. A new fluorescent probe to study spontaneous lipid transfer.
AuthorsArvinte T, Hildenbrand K
JournalBiochim Biophys Acta
PubMed ID6547853
Migration of the fluorescent phospholipid N-(7-nitro-2,1,3-benzoxadiazol-4-yl)-L-alpha-dilauroylphosphati dylethanolamine between small sonicated egg phosphatidylcholine vesicles was studied by use of the fluorescence resonance energy transfer method. Contrary to the results of lipid transfer experiments reported for acyl chain NBD-labeled phospholipids (Nichols, J.W. and Pagano, R.E. (1982) Biochemistry 21, 1720-1728), the migration kinetics ... More
Single-molecule anisotropy imaging
AuthorsHarms GS, Sonnleitner M, Schutz GJ, Gruber HJ, Schmidt T
JournalBiophys J
PubMed ID10545384
A novel method, single-molecule anisotropy imaging, has been employed to simultaneously study lateral and rotational diffusion of fluorescence-labeled lipids on supported phospholipid membranes. In a fluid membrane composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, in which the rotational diffusion time is on the order of the excited-state lifetime of the fluorophore rhodamine, a rotational ... More
Agonist-induced PIP(2) hydrolysis inhibits cortical actin dynamics: regulation at a global but not at a micrometer scale.
Authorsvan Rheenen J, Jalink K
JournalMol Biol Cell
PubMed ID12221130
Phosphatidylinositol 4, 5-bisphosphate (PIP(2)) at the inner leaflet of the plasma membrane has been proposed to locally regulate the actin cytoskeleton. Indeed, recent studies that use GFP-tagged pleckstrin homology domains (GFP-PH) as fluorescent PIP(2) sensors suggest that this lipid is enriched in membrane microdomains. Here we report that this concept ... More
Synthesis, characterization, and application of fluorescence sensing lipobeads for intracellular pH measurements.
AuthorsMcNamara KP, Nguyen T, Dumitrascu G, Ji J, Rosenzweig N, Rosenzweig Z
JournalAnal Chem
PubMed ID11476221
This paper describes the synthesis and characterization of micrometric phospholipid-coated polystyrene particles, named lipobeads, with pH-sensing capability and their application for intracellular pH measurements in murine macrophages. The phospholipids used to coat the particles are labeled with fluorescein (a pH-sensitive dye) and tetramethylrhodamine (a pH-insensitive dye), which serves as a ... More
Direct measurement of trans-Golgi pH in living cells and regulation by second messengers.
AuthorsSeksek O, Biwersi J, Verkman AS
JournalJ Biol Chem
PubMed ID7890600
In the endocytic compartment, an acidic pH plays a key role in receptor and ligand sorting, vesicular transport, and protein degradation. In the secretory compartment, indirect estimates of trans-Golgi pH based on partitioning of weak bases and following viral infection suggest a mildly acidic pH of > 6.0. We developed ... More
Visualizing association of N-ras in lipid microdomains: influence of domain structure and interfacial adsorption.
AuthorsNicolini C, Baranski J, Schlummer S, Palomo J, Lumbierres-Burgues M, Kahms M, Kuhlmann J, Sanchez S, Gratton E, Waldmann H, Winter R
JournalJ Am Chem Soc
PubMed ID16390147
In this study, two-photon fluorescence microscopy on giant unilamellar vesicles and tapping-mode atomic force microscopy (AFM) are applied to follow the insertion of a fluorescently (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene, BODIPY) labeled and completely lipidated (hexadecylated and farnesylated) N-Ras protein into heterogeneous lipid bilayer systems. The bilayers consist of the canonical raft mixture 1-palmitoyl-2-oleoylphosphatidylcholine ... More
Cholesterol depletion induces solid-like regions in the plasma membrane.
AuthorsNishimura SY, Vrljic M, Klein LO, McConnell HM, Moerner WE
JournalBiophys J
PubMed ID16272447
Glycosylphosphatidylinositol-linked and transmembrane major histocompatibility complex (MHC) class II I-E(k) proteins, as well as N-(6-tetramethylrhodaminethiocarbamoyl)-1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (Tritc-DHPE), are used as probes to determine the effect of cholesterol concentration on the organization of the plasma membrane at temperatures in the range 22 degrees C-42 degrees C. Cholesterol depletion caused a decrease in ... More
DNA release from lipoplexes by anionic lipids: correlation with lipid mesomorphism, interfacial curvature, and membrane fusion.
AuthorsTarahovsky YS, Koynova R, MacDonald RC
JournalBiophys J
PubMed ID15298910
DNA release from lipoplexes is an essential step during lipofection and is probably a result of charge neutralization by cellular anionic lipids. As a model system to test this possibility, fluorescence resonance energy transfer between DNA and lipid covalently labeled with Cy3 and BODIPY, respectively, was used to monitor the ... More
Overexpression of the myelin proteolipid protein leads to accumulation of cholesterol and proteolipid protein in endosomes/lysosomes: implications for Pelizaeus-Merzbacher disease.
AuthorsSimons M, Kramer EM, Macchi P, Rathke-Hartlieb S, Trotter J, Nave KA, Schulz JB
JournalJ Cell Biol
PubMed ID11956232
Duplications and overexpression of the proteolipid protein (PLP) gene are known to cause the dysmyelinating disorder Pelizaeus-Merzbacher disease (PMD). To understand the cellular response to overexpressed PLP in PMD, we have overexpressed PLP in BHK cells and primary cultures of oligodendrocytes with the Semliki Forest virus expression system. Overexpressed PLP ... More
Activation of RGS9-1GTPase acceleration by its membrane anchor, R9AP.
AuthorsHu G, Zhang Z, Wensel TG
JournalJ Biol Chem
PubMed ID12560335
The GTPase-accelerating protein (GAP) complex RGS9-1.G beta(5) plays an important role in the kinetics of light responses by accelerating the GTP hydrolysis of G alpha(t) in vertebrate photoreceptors. Much, but not all, of this complex is tethered to disk membranes by the transmembrane protein R9AP. To determine the effect of ... More
Distribution and lateral mobility of glycine receptors on cultured spinal cord neurons.
AuthorsSrinivasan Y, Guzikowski AP, Haugland RP, Angelides KJ
JournalJ Neurosci
PubMed ID2156968
Strychnine is one of the most potent antagonists of glycine-mediated inhibitory conductances in the mammalian spinal cord. In order to examine the distribution of glycine receptors (GlyRs) on neuronal cells, 2 novel fluorescent strychnine derivatives were synthesized and characterized chemically, spectroscopically, and biologically. Both compounds retain their biological activity after ... More
Modeling the endosomal escape of cell-penetrating peptides: transmembrane pH gradient driven translocation across phospholipid bilayers.
AuthorsMagzoub M, Pramanik A, Gräslund A
JournalBiochemistry
PubMed ID16274236
Cell-penetrating peptides (CPPs) are able to mediate the efficient cellular uptake of a wide range of cargoes. Internalization of a number of CPPs requires uptake by endocytosis, initiated by binding to anionic cell surface heparan sulfate (HS), followed by escape from endosomes. To elucidate the endosomal escape mechanism, we have ... More
Identification of some of the major groups of bacteria in efficient and nonefficient biological phosphorus removal activated sludge systems.
AuthorsBond PL, Erhart R, Wagner M, Keller J, Blackall LL
JournalAppl Environ Microbiol
PubMed ID10473419
To investigate the bacteria that are important to phosphorus (P) removal in activated sludge, microbial populations were analyzed during the operation of a laboratory-scale reactor with various P removal performances. The bacterial population structure, analyzed by fluorescence in situ hybridization (FISH) with oligonucleotides probes complementary to regions of the 16S ... More
Distance between skeletal protein 4.1 and the erythrocyte membrane bilayer measured by resonance energy transfer.
AuthorsShahrokh Z, Verkman AS, Shohet SB
JournalJ Biol Chem
PubMed ID2050702
To assess the molecular architecture of the human erythrocyte skeletal protein 4.1:bilayer interface, the distance between a donor sulfhydryl-specific fluorescent probe attached to a region near the glycophorin-binding domain of protein 4.1 and an acceptor lipophilic probe in the exposed leaflet of inside-out vesicles (IOVs) was measured by fluorescence resonance ... More
Cyclodextrin-mediated removal of sterols from monolayers: effects of sterol structure and phospholipids on desorption rate.
AuthorsOhvo H, Slotte JP
JournalBiochemistry
PubMed ID8672506
In this study, we have examined a number of parameters which affect the rate of sterol desorption from a model membrane surface (a monolayer at the air/water interface) to cyclodextrins (CD) in the aqueous subphase. The desorption experiments were carried out at a constant lateral surface pressure with a zero-order ... More
Electrostatic sequestration of PIP2 on phospholipid membranes by basic/aromatic regions of proteins.
AuthorsGambhir A, Hangyás-Mihályné G, Zaitseva I, Cafiso DS, Wang J, Murray D, Pentyala SN, Smith SO, McLaughlin S
JournalBiophys J
PubMed ID15041659
The basic effector domain of myristoylated alanine-rich C kinase substrate (MARCKS), a major protein kinase C substrate, binds electrostatically to acidic lipids on the inner leaflet of the plasma membrane; interaction with Ca2+/calmodulin or protein kinase C phosphorylation reverses this binding. Our working hypothesis is that the effector domain of ... More
Low pH fusion of mouse liver nuclei with liposomes bearing covalently bound lysozyme.
AuthorsArvinte T, Wahl P, Nicolau C
JournalBiochim Biophys Acta
PubMed ID3580361
Lysozyme covalently bound to liposomes induces the fusion of liposomes with isolated mouse liver nuclei. The fusion behavior is very similar to the case of erythrocyte ghosts (Arvinte, T., Hildenbrand, K., Wahl, P. and Nicolau, C. (1986) Proc. Natl. Acad. Sci. USA 83, 962-966). Kinetic studies showed that membrane lipid ... More