Channels formed with a mutant prion protein PrP(82-146) homologous to a 7-kDa fragment in diseased brain of GSS patients

2003 ◽  
Vol 285 (4) ◽  
pp. C862-C872 ◽  
Author(s):  
Randa Bahadi ◽  
Peter V. Farrelly ◽  
Bronwyn L. Kenna ◽  
Joseph I. Kourie ◽  
Fabrizio Tagliavini ◽  
...  
Keyword(s):  
Ion Channels ◽  
Prion Protein ◽  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Amyloid Fibrils ◽  
Time Dependent ◽  
Cation Channels ◽  
Wild Type ◽  
Fast Kinetics ◽  
Neuronal Membranes

A major prion protein (PrP) mutant that forms amyloid fibrils in the diseased brain of patients with Gerstmann-Sträussler-Scheinker syndrome (GSS) is a fragment of 7 kDa spanning from residues 81-82 to 144-153 of PrP. Analysis of ionic membrane currents, recorded with a libid bilayer technique, revealed that the wild-type fragment PrP(82-146) WT and the partially scrambled PrP(82-146) (127-146) SC are capable of forming heterogenous ion channels that are similar to those channels formed with PrP(106-126). In contrast, PrP(82-146) peptides in which the region from residue 106 to 126 had been scrambled (SC) showed a reduction in interaction with lipid membranes and did not form channels. The PrP(82-146) WT- and PrP(82-146) (127-146) SC-formed cation channels with fast kinetics are Cu2+ sensitive and rifampicin (RIF) insensitive, whereas the time-dependent inactivating channels formed by these same peptides are both Cu2+ and RIF insensitive. The presence of RIF in the solution before the addition of PrP(82-146) WT or PrP(82-146) (127-146) SC affected their incorporation into the lipid bilayers. PrP(82-146) WT and PrP(82-146) (127-146) SC fast cation channels formed in the presence of RIF appeared in an electrically semisilent state or an inactivated state. Increasing [Cd2+] cis enhanced the incorporation of PrP(82-146) WT and PrP(82-146) (127-146) SC channels formed in the presence of RIF. We conclude that the major PrP mutant fragment in the diseased brain of GSS patients is prone to form channels in neuronal membranes, causing their dysfunction. We propose that Cd2+ may accentuate the neurotoxicity of this channel-forming PrP fragment by enhancing its incorporation into the membrane.

scholarly journals The Amino-Terminal Region of Vpr from Human Immunodeficiency Virus Type 1 Forms Ion Channels and Kills Neurons

1999 ◽  
Vol 73 (5) ◽  
pp. 4230-4238 ◽  
Author(s):  
S. C. Piller ◽  
G. D. Ewart ◽  
D. A. Jans ◽  
P. W. Gage ◽  
G. B. Cox
Keyword(s):  
Amino Acids ◽  
Human Immunodeficiency Virus ◽  
Cell Death ◽  
Ion Channels ◽  
Ion Channel ◽  
Lipid Bilayers ◽  
Planar Lipid Bilayers ◽  
Wild Type ◽  
Immunodeficiency Virus

ABSTRACT We have previously reported that the accessory protein Vpr from human immunodeficiency virus type 1 forms cation-selective ion channels in planar lipid bilayers and is able to depolarize intact cultured neurons by causing an inward sodium current, resulting in cell death. In this study, we used site-directed mutagenesis and synthetic peptides to identify the structural regions responsible for the above functions. Mutations in the N-terminal region of Vpr were found to affect channel activity, whereas this activity was not affected by mutations in the hydrophobic region of Vpr (amino acids 53 to 71). Analysis of mutants containing changes in the basic C terminus confirmed previous results that this region, although not necessary for ion channel function, was responsible for the observed rectification of wild-type Vpr currents. A peptide comprising the first 40 N-terminal amino acids of Vpr (N40) was found to be sufficient to form ion channels similar to those caused by wild-type Vpr in planar lipid bilayers. Furthermore, N40 was able to cause depolarization of the plasmalemma and cell death in cultured hippocampal neurons with a time course similar to that seen with wild-type Vpr, supporting the idea that this region is responsible for Vpr ion channel function and cytotoxic effects. Since Vpr is found in the serum and cerebrospinal fluids of AIDS patients, these results may have significance for AIDS pathology.

Investigating the Function of Ion Channels in Tethered Lipid Membranes by Impedance Spectroscopy

MRS Bulletin ◽  
2005 ◽  
Vol 30 (3) ◽  
pp. 207-210 ◽  
Author(s):  
Samuel Terrettaz ◽  
Horst Vogel
Keyword(s):  
Ion Channels ◽  
Impedance Spectroscopy ◽  
Ligand Binding ◽  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Gold Electrodes ◽  
Channel Activity ◽  
Electrophysiological Measurements ◽  
Supported Lipid Membranes ◽  
Specific Ligand

AbstractThe function of biologically important ion channels can be measured in supported lipid membranes by impedance spectroscopy. This approach offers substantial advantages over traditional electrophysiological measurements. In this article, we present an overview of the field, with a special emphasis on the reconstitution of ion channels in lipid bilayers tethered to gold electrodes and the modulation of their channel activity by specific ligand binding.

scholarly journals Effect of lipid saturation on amyloid-beta peptide partitioning and aggregation in neuronal membranes: molecular dynamics simulations

2019 ◽  
Vol 48 (8) ◽  
pp. 813-824 ◽  
Author(s):  
Nikolaos Ntarakas ◽  
Inna Ermilova ◽  
Alexander P. Lyubartsev
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Neuronal Membranes ◽  
Chemical Background ◽  
Dynamics Simulations ◽  
Polyunsaturated Lipids

Abstract Aggregation of amyloid-$$\beta $$β (Aβ) peptides, cleaved from the amyloid precursor protein, is known as a precursor of the Alzheimer’s disease (AD). It is also known that Alzheimer’s disease is characterized by a substantial decrease of the amount of polyunsaturated lipids in the neuronal membranes of the frontal gray matter. To get insight into possible interconnection of these phenomena, we have carried out molecular dynamics simulations of two fragments of A$$\beta $$β peptide, A$$\beta $$β$$_{1-28}$$1-28 and A$$\beta $$β$$_{26-40}$$26-40, in four different lipid bilayers: two monocomponent ones (14:0-14:0 PC, 18:0-22:6 PC), and two bilayers containing mixtures of 18:0-18:0 PE, 22:6-22:6 PE, 16:0-16:0 PC and 18:1-18:1 PC lipids of composition mimicking neuronal membranes in a “healthy” and “AD” brain. The simulations showed that the presence of lipids with highly unsaturated 22:6cis fatty acids chains strongly affects the interaction of amyloid-$$\beta $$β peptides with lipid membranes. The polyunsaturated lipids cause stronger adsorption of A$$\beta $$β-peptides by the membrane and lead to weaker binding between peptides when the latter form aggregates. This difference in the behaviour observed in monocomponent bilayers is propagated in a similar fashion to the mixed membranes mimicking composition of neuronal membranes in “healthy” and “AD” brains, with “healthy” membrane having higher fraction of polyunsaturated lipids. Our simulations give strong indication that it can be physical–chemical background of the interconnection between amyloid fibrillization causing Alzheimer’s disease, and content of polyunsaturated lipids in the neuronal membranes.

scholarly journals Fluorescence Approaches for Characterizing Ion Channels in Synthetic Bilayers

Membranes ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 857
Author(s):  
Md. Sirajul Islam ◽  
James P. Gaston ◽  
Matthew A. B. Baker
Keyword(s):  
Ion Channels ◽  
Membrane Proteins ◽  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Protein Composition ◽  
Cellular Processes ◽  
Model Lipid Membranes ◽  
Wide Range ◽  
Lipid Environment

Ion channels are membrane proteins that play important roles in a wide range of fundamental cellular processes. Studying membrane proteins at a molecular level becomes challenging in complex cellular environments. Instead, many studies focus on the isolation and reconstitution of the membrane proteins into model lipid membranes. Such simpler, in vitro, systems offer the advantage of control over the membrane and protein composition and the lipid environment. Rhodopsin and rhodopsin-like ion channels are widely studied due to their light-interacting properties and are a natural candidate for investigation with fluorescence methods. Here we review techniques for synthesizing liposomes and for reconstituting membrane proteins into lipid bilayers. We then summarize fluorescence assays which can be used to verify the functionality of reconstituted membrane proteins in synthetic liposomes.

Observation of Concanavalin-A receptors on hydrated planar erythrocyte membrane film by in situ electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 608-609
Author(s):  
Neng-Bo He ◽  
S.W. Hui
Keyword(s):  
Lipid Bilayers ◽  
Erythrocyte Membrane ◽  
Lipid Membranes ◽  
Surface Film ◽  
Biological Membranes ◽  
Electron Microscopic Observation ◽  
Electron Microscopic ◽  
Black Lipid Membranes ◽  
Fine Mesh ◽  
Planar Films

Monolayers and planar "black" lipid membranes have been widely used as models for studying the structure and properties of biological membranes. Because of the lack of a suitable method to prepare these membranes for electron microscopic observation, their ultrastructure is so far not well understood. A method of forming molecular bilayers over the holes of fine mesh grids was developed by Hui et al. to study hydrated and unsupported lipid bilayers by electron diffraction, and to image phase separated domains by diffraction contrast. We now adapted the method of Pattus et al. of spreading biological membranes vesicles on the air-water interfaces to reconstitute biological membranes into unsupported planar films for electron microscopic study. hemoglobin-free human erythrocyte membrane stroma was prepared by hemolysis. The membranes were spreaded at 20°C on balanced salt solution in a Langmuir trough until a surface pressure of 20 dyne/cm was reached. The surface film was repeatedly washed by passing to adjacent troughs over shallow partitions (fig. 1).

scholarly journals Cardiolipin-Containing Lipid Membranes Attract the Bacterial Cell Division Protein DivIVA

2021 ◽  
Vol 22 (15) ◽  
pp. 8350
Author(s):  
Naďa Labajová ◽  
Natalia Baranova ◽  
Miroslav Jurásek ◽  
Robert Vácha ◽  
Martin Loose ◽  
...  
Keyword(s):  
Cell Division ◽  
Lipid Bilayers ◽  
Bacterial Cell ◽  
Lipid Membranes ◽  
Model Organism ◽  
Active Role ◽  
Membrane Curvature ◽  
Bacterial Cell Division ◽  
Division Site ◽  
Clostridioides Difficile

DivIVA is a protein initially identified as a spatial regulator of cell division in the model organism Bacillus subtilis, but its homologues are present in many other Gram-positive bacteria, including Clostridia species. Besides its role as topological regulator of the Min system during bacterial cell division, DivIVA is involved in chromosome segregation during sporulation, genetic competence, and cell wall synthesis. DivIVA localizes to regions of high membrane curvature, such as the cell poles and cell division site, where it recruits distinct binding partners. Previously, it was suggested that negative curvature sensing is the main mechanism by which DivIVA binds to these specific regions. Here, we show that Clostridioides difficile DivIVA binds preferably to membranes containing negatively charged phospholipids, especially cardiolipin. Strikingly, we observed that upon binding, DivIVA modifies the lipid distribution and induces changes to lipid bilayers containing cardiolipin. Our observations indicate that DivIVA might play a more complex and so far unknown active role during the formation of the cell division septal membrane.

scholarly journals Temperature-Dependent Structural Variability of Prion Protein Amyloid Fibrils

2021 ◽  
Vol 22 (10) ◽  
pp. 5075
Author(s):  
Mantas Ziaunys ◽  
Andrius Sakalauskas ◽  
Kamile Mikalauskaite ◽  
Ruta Snieckute ◽  
Vytautas Smirnovas
Keyword(s):  
Protein Aggregation ◽  
Prion Protein ◽  
Amyloid Fibrils ◽  
Prion Diseases ◽  
Morphological Properties ◽  
Large Sample Size ◽  
Structural Variations ◽  
Temperature Dependent ◽  
Protein Fibrils ◽  
Propagation Properties

Prion protein aggregation into amyloid fibrils is associated with the onset and progression of prion diseases—a group of neurodegenerative amyloidoses. The process of such aggregate formation is still not fully understood, especially regarding their polymorphism, an event where the same type of protein forms multiple, conformationally and morphologically distinct structures. Considering that such structural variations can greatly complicate the search for potential antiamyloid compounds, either by having specific propagation properties or stability, it is important to better understand this aggregation event. We have recently reported the ability of prion protein fibrils to obtain at least two distinct conformations under identical conditions, which raised the question if this occurrence is tied to only certain environmental conditions. In this work, we examined a large sample size of prion protein aggregation reactions under a range of temperatures and analyzed the resulting fibril dye-binding, secondary structure and morphological properties. We show that all temperature conditions lead to the formation of more than one fibril type and that this variability may depend on the state of the initial prion protein molecules.

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