scholarly journals Imaging non-classical mechanical responses of lipid membranes using molecular rotors

2021 ◽  
Author(s):  
Miguel Paez-Perez ◽  
ismael lópez-duarte ◽  
Aurimas Vysniauskas ◽  
Nicholas Jan Brooks ◽  
Marina Konstantinovna Kuimova
Keyword(s):  
Direct Effect ◽  
Lipid Membranes ◽  
Molecular Rotors ◽  
Membrane Tension ◽  
Cellular Membranes ◽  
Cellular Adaptation ◽  
Lipid Packing ◽  
Mechanical Responses

Lipid packing in cellular membranes has a direct effect on membrane tension and microviscosity, and plays a central role in cellular adaptation, homeostasis and disease. According to conventional mechanical descriptions,...

scholarly journals Twisting and tilting of a mechanosensitive molecular probe detects order in membranes

2020 ◽  
Vol 11 (22) ◽  
pp. 5637-5649 ◽  
Author(s):  
Giuseppe Licari ◽  
Karolina Strakova ◽  
Stefan Matile ◽  
Emad Tajkhorshid
Keyword(s):  
Fluorescent Probe ◽  
Molecular Probe ◽  
Membrane Tension ◽  
Lipid Packing

Flipper-TR fluorescent probe detects lipid packing and membrane tension by twisting its mechanosensitive flippers and by changing its orientation in the membrane.

scholarly journals Evaluation of Analgesic Activities of Tremetone Derivatives Isolated from the Chilean Altiplano Medicine Parastrephia lepidophylla

2012 ◽  
Vol 7 (5) ◽  
pp. 1934578X1200700 ◽  
Author(s):  
Julio Benites ◽  
Eunices Gutierrez ◽  
José López ◽  
Mauricio Rojas ◽  
Leonel Rojo ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Traditional Medicine ◽  
Signaling Pathway ◽  
Direct Effect ◽  
Lipid Membranes ◽  
Analgesic Effect ◽  
Opiate Receptors ◽  
Log P ◽  
Chilean Altiplano ◽  
Analgesic Activities

Parastrephia lepidophylla, family Asteraceae, has ancient use in traditional medicine in the region of Tarapacá, Chile. Bioguided fractionation of extracts of this plant was undertaken in the search for compounds with analgesic and antioxidant activity. Two benzofuran derivatives were isolated as the major components of this plant, identified as tremetone 1 and methoxytremetone 6. Remarkably, neither of these showed antioxidant activity, but tremetone 1 exhibited a morphine-like analgesic property. Reduction of this analgesic effect by naloxone suggests a direct effect on opiate receptors as a possible signaling pathway. However, both the low diffusion across lipid membranes (PAMPA assay) and the lipophilicity (Log P) shown by tremetone 1 make elusive the mechanism explaining its induced analgesia.

scholarly journals A new approach for investigating the response of lipid membranes to electrocompression by coupling droplet mechanics and membrane biophysics

2019 ◽  
Vol 16 (161) ◽  
pp. 20190652 ◽  
Author(s):  
Joyce El-Beyrouthy ◽  
Michelle M. Makhoul-Mansour ◽  
Graham Taylor ◽  
Stephen A. Sarles ◽  
Eric C. Freeman
Keyword(s):  
Contact Angle ◽  
Lipid Membranes ◽  
Bilayer Membrane ◽  
Residual Energy ◽  
Membrane Biophysics ◽  
Membrane Properties ◽  
Lipid Monolayer ◽  
Membrane Tension ◽  
Membrane Area ◽  
Transmembrane Voltage

A new method for quantifying lipid–lipid interactions within biomimetic membranes undergoing electrocompression is demonstrated by coupling droplet mechanics and membrane biophysics. The membrane properties are varied by altering the lipid packing through the introduction of cholesterol. Pendant drop tensiometry is used to measure the lipid monolayer tension at an oil–water interface. Next, two lipid-coated aqueous droplets are manipulated into contact to form a bilayer membrane at their adhered interface. The droplet geometries are captured from two angles to provide accurate measurements of both the membrane area and the contact angle between the adhered droplets. Combining the monolayer tension and contact angle measurements enables estimations of the membrane tension with respect to lipid composition. Then, the membrane is electromechanically compressed using a transmembrane voltage. Electrostatic pressure, membrane tension and the work necessary for bilayer thinning are tracked, and a model is proposed to capture the mechanics of membrane compression. The results highlight that a previously unaccounted for energetic term is produced during compression, potentially reflecting changes in the lateral membrane structure. This residual energy is eliminated in cases with cholesterol mole fractions of 0.2 and higher, suggesting that cholesterol diminishes these adjustments.

scholarly journals Characterization of Fusion Determinants Points to the Involvement of Three Discrete Regions of Both E1 and E2 Glycoproteins in the Membrane Fusion Process of Hepatitis C Virus

2007 ◽  
Vol 81 (16) ◽  
pp. 8752-8765 ◽  
Author(s):  
Dimitri Lavillette ◽  
Eve-Isabelle Pécheur ◽  
Peggy Donot ◽  
Judith Fresquet ◽  
Jennifer Molle ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Membrane Fusion ◽  
Conformational Changes ◽  
Lipid Membranes ◽  
Fusion Process ◽  
Fusion Peptides ◽  
Cellular Membranes ◽  
Enveloped Virus ◽  
Molecular Events

ABSTRACT Infection of eukaryotic cells by enveloped viruses requires the merging of viral and cellular membranes. Highly specific viral surface glycoproteins, named fusion proteins, catalyze this reaction by overcoming inherent energy barriers. Hepatitis C virus (HCV) is an enveloped virus that belongs to the genus Hepacivirus of the family Flaviviridae. Little is known about the molecular events that mediate cell entry and membrane fusion for HCV, although significant progress has been made due to recent developments in infection assays. Here, using infectious HCV pseudoparticles (HCVpp), we investigated the molecular basis of HCV membrane fusion. By searching for classical features of fusion peptides through the alignment of sequences from various HCV genotypes, we identified six regions of HCV E1 and E2 glycoproteins that present such characteristics. We introduced conserved and nonconserved amino acid substitutions in these regions and analyzed the phenotype of HCVpp generated with mutant E1E2 glycoproteins. This was achieved by (i) quantifying the infectivity of the pseudoparticles, (ii) studying the incorporation of E1E2 and their capacity to mediate receptor binding, and (iii) determining their fusion capacity in cell-cell and liposome/HCVpp fusion assays. We propose that at least three of these regions (i.e., at positions 270 to 284, 416 to 430, and 600 to 620) play a role in the membrane fusion process. These regions may contribute to the merging of viral and cellular membranes either by interacting directly with lipid membranes or by assisting the fusion process through their involvement in the conformational changes of the E1E2 complex at low pH.

Measurement of membrane tension of free standing lipid bilayers via laser-induced surface deformation spectroscopy

Soft Matter ◽  
2015 ◽  
Vol 11 (44) ◽  
pp. 8641-8647 ◽  
Author(s):  
Tomohiko Takei ◽  
Tatsuya Yaguchi ◽  
Takuya Fujii ◽  
Tomonori Nomoto ◽  
Taro Toyota ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Surface Deformation ◽  
Membrane Tension ◽  
Free Standing ◽  
Black Lipid Membranes ◽  
Non Invasive ◽  
Invasive Measurement

Non-invasive measurement of the membrane tension of free-standing black lipid membranes (BLMs), with sensitivity on the order of μN m−1, was achieved using laser-induced surface deformation (LISD) spectroscopy.

scholarly journals Microplastics destabilize lipid membranes by mechanical stretching

2021 ◽  
Vol 118 (31) ◽  
pp. e2104610118
Author(s):  
Jean-Baptiste Fleury ◽  
Vladimir A. Baulin
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Cumulative Effect ◽  
Health Impact ◽  
Membrane Tension ◽  
Membrane Area ◽  
Theoretical Approaches ◽  
Living Organisms ◽  
The Impact ◽  
Mechanical Stretching

Estimated millions of tons of plastic are dumped annually into oceans. Plastic has been produced only for 70 y, but the exponential rise of mass production leads to its widespread proliferation in all environments. As a consequence of their large abundance globally, microplastics are also found in many living organisms including humans. While the health impact of digested microplastics on living organisms is debatable, we reveal a physical mechanism of mechanical stretching of model cell lipid membranes induced by adsorbed micrometer-sized microplastic particles most commonly found in oceans. Combining experimental and theoretical approaches, we demonstrate that microplastic particles adsorbed on lipid membranes considerably increase membrane tension even at low particle concentrations. Each particle adsorbed at the membrane consumes surface area that is proportional to the contact area between particle and the membrane. Although lipid membranes are liquid and able to accommodate mechanical stress, the relaxation time is much slower than the rate of adsorption; thus, the cumulative effect from arriving microplastic particles to the membrane leads to the global reduction of the membrane area and increase of membrane tension. This, in turn, leads to a strong reduction of membrane lifetime. The effect of mechanical stretching of microplastics on living cells membranes was demonstrated by using the aspiration micropipette technique on red blood cells. The described mechanical stretching mechanism on lipid bilayers may provide better understanding of the impact of microplastic particles in living systems.

scholarly journals Effects of Cholesterol Concentration and Osmolarity on the Fluidity and Membrane Tension of Free-standing Black Lipid Membranes

2018 ◽  
Vol 34 (11) ◽  
pp. 1237-1242 ◽  
Author(s):  
Tomonori NOMOTO ◽  
Masahiro TAKAHASHI ◽  
Takuya FUJII ◽  
Luca CHIARI ◽  
Taro TOYOTA ◽  
...  
Keyword(s):  
Lipid Membranes ◽  
Cholesterol Concentration ◽  
Membrane Tension ◽  
Free Standing ◽  
Black Lipid Membranes

scholarly journals Imaging phase separation in model lipid membranes through the use of BODIPY based molecular rotors

2015 ◽  
Vol 17 (28) ◽  
pp. 18393-18402 ◽  
Author(s):  
Michael R. Dent ◽  
Ismael López-Duarte ◽  
Callum J. Dickson ◽  
Niall D. Geoghegan ◽  
Jonathan M. Cooper ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Phase Separation ◽  
Fluorescence Spectroscopy ◽  
Molecular Dynamics Simulations ◽  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Molecular Rotors ◽  
Model Lipid Membranes ◽  
Dynamics Simulations

Viscosity in the phase-separated lipid bilayers is investigated through the use of fluorescence spectroscopy and molecular dynamics simulations.

Sign in / Sign up

Export Citation Format

Share Document