scholarly journals The Effect of the Osmotically Active Compound Concentration Difference on the Passive Water and Proton Fluxes across a Lipid Bilayer

2021 ◽  
Vol 22 (20) ◽  
pp. 11099
Author(s):  
Magdalena Przybyło ◽  
Dominik Drabik ◽  
Joanna Doskocz ◽  
Aleš Iglič ◽  
Marek Langner
Keyword(s):  
Lipid Bilayer ◽  
Water Flow ◽  
Active Compound ◽  
Pore Formation ◽  
Biological Significance ◽  
Bending Rigidity ◽  
Hydrophobic Membrane ◽  
Concentration Difference ◽  
Lipid Pore ◽  
Pore Opening

The molecular details of the passive water flux across the hydrophobic membrane interior are still a matter of debate. One of the postulated mechanisms is the spontaneous, water-filled pore opening, which facilitates the hydrophilic connection between aqueous phases separated by the membrane. In the paper, we provide experimental evidence showing that the spontaneous lipid pore formation correlates with the membrane mechanics; hence, it depends on the composition of the lipid bilayer and the concentration of the osmotically active compound. Using liposomes as an experimental membrane model, osmotically induced water efflux was measured with the stopped-flow technique. Shapes of kinetic curves obtained at low osmotic pressure differences are interpreted in terms of two events: the lipid pore opening and water flow across the aqueous channel. The biological significance of the dependence of the lipid pore formation on the concentration difference of an osmotically active compound was illustrated by the demonstration that osmotically driven water flow can be accompanied by the dissipation of the pH gradient. The application of the Helfrich model to describe the probability of lipid pore opening was validated by demonstrating that the probability of pore opening correlates with the membrane bending rigidity. The correlation was determined by experimentally derived bending rigidity coefficients and probabilities of lipid pores opening.

Mechanistic Insights into Pore Formation by an α-Pore Forming Toxin: Protein and Lipid Bilayer Interactions of Cytolysin A

2020 ◽  
Vol 54 (1) ◽  
pp. 120-131
Author(s):  
Pradeep Sathyanarayana ◽  
Sandhya S. Visweswariah ◽  
K. Ganapathy Ayappa
Keyword(s):  
Lipid Bilayer ◽  
Pore Formation ◽  
Toxin Protein

Application of the Smoluchowski equation with a source term to the model of lipid pore formation during a phase transition

BIOPHYSICS ◽  
2016 ◽  
Vol 61 (6) ◽  
pp. 936-941 ◽  
Author(s):  
A. A. Anosov ◽  
A. A. Sharakshane ◽  
E. Yu. Smirnova ◽  
O. Yu. Nemchenko
Keyword(s):  
Phase Transition ◽  
Pore Formation ◽  
Source Term ◽  
Smoluchowski Equation ◽  
Lipid Pore

scholarly journals Membrane Structures of the Hemifusion-Inducing Fusion Peptide Mutant G1S and theFusion-Blocking Mutant G1V of Influenza Virus HemagglutininSuggest a Mechanism for Pore Opening in MembraneFusion

2005 ◽  
Vol 79 (18) ◽  
pp. 12065-12076 ◽  
Author(s):  
Yinling Li ◽  
Xing Han ◽  
Alex L. Lai ◽  
John H. Bushweller ◽  
David S. Cafiso ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Membrane Fusion ◽  
Lipid Bilayer ◽  
Membrane Surface ◽  
Helical Structure ◽  
Fusion Peptide ◽  
Membrane Structures ◽  
Influenza Virus Hemagglutinin ◽  
Target Membrane ◽  
Pore Opening

ABSTRACT Influenza virus hemagglutinin (HA)-mediated membrane fusion is initiated by a conformational change that releases a V-shaped hydrophobic fusion domain, the fusion peptide, into the lipid bilayer of the target membrane. The most N-terminal residue of this domain, a glycine, is highly conserved and is particularly critical for HA function; G1S and G1V mutant HAs cause hemifusion and abolish fusion, respectively. We have determined the atomic resolution structures of the G1S and G1V mutant fusion domains in membrane environments. G1S forms a V with a disrupted “glycine edge” on its N-terminal arm and G1V adopts a slightly tilted linear helical structure in membranes. Abolishment of the kink in G1V results in reduced hydrophobic penetration of the lipid bilayer and an increased propensity to formβ -structures at the membrane surface. These results underline the functional importance of the kink in the fusion peptide and suggest a structural role for the N-terminal glycine ridge in viral membrane fusion.

scholarly journals Synaptobrevin-2 C-terminal Flexible Region Regulates the Discharge of Catecholamine through the Fusion Pore

2018 ◽  
Author(s):  
Annita N. Weiss
Keyword(s):  
Membrane Potential ◽  
Lipid Bilayer ◽  
Chromaffin Cells ◽  
Pore Formation ◽  
Transmembrane Domain ◽  
Flash Photolysis ◽  
Fusion Pore ◽  
Snare Protein ◽  
Head Groups ◽  
Flexible Region

AbstractThe discharge of neurotransmitters from vesicles is a regulated process. Synaptobrevin-2 a SNARE protein, participates in this process through its interaction with other SNARE and associate proteins. Synaptobrevin-2 transmembrane domain is embedded into the vesicle lipid bilayer except for its last three residues. These residues are hydrophilic and constitute synaptobrevin-2 C-terminal flexible region. This region interacts with the intravesicular lipid bilayer phosphate head groups to initiate the fusion pore formation. Here it is shown that, this region also modulates the intravesicular membrane potential thereby the discharged of catecholamine. Synapotobrevin-2 Y113 residue was mutated to lysine or glutamate. The effects of these mutations on the exocytotic process in chromaffin cells were assessed using capacitance measurements, combined with amperometry and stimulation by flash photolysis of caged Ca2+. Both Y113E and Y113K mutations reduced the amplitudes of vesicle fusions and reduced the rates of release of catecholamine molecules in quanta release events. Further investigation revealed that the proximity of these charged residues near the vesicle lipid bilayer most likely changed the intravesicular potential, thereby slowing the flux of ions through the fusion pore, hence reducing the rate of catecholamine secretion. These results suggest that catecholamine efflux is couple with the intravesicular membrane potential.

Formation and stabilization of pores in bilayer membranes by peptide-like amphiphilic polymers

Soft Matter ◽  
2018 ◽  
Vol 14 (13) ◽  
pp. 2526-2534 ◽  
Author(s):  
Ankush Checkervarty ◽  
Marco Werner ◽  
Jens-Uwe Sommer
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Lipid Bilayer ◽  
Pore Formation ◽  
Amphiphilic Polymers ◽  
Amphiphilic Copolymers ◽  
Lipid Bilayer Membranes ◽  
Bilayer Membranes ◽  
Fluid Membrane ◽  
Brush Model

We study pore formation in models of lipid bilayer membranes interacting with amphiphilic copolymers mimicking anti-microbial peptides using Monte Carlo simulations and we rationalize our results by a simple brush-model for the fluid membrane.

Rapid and Resilient Detection of Toxin Pore Formation Using a Lipid Bilayer Array

Small ◽  
2020 ◽  
Vol 16 (49) ◽  
pp. 2005550 ◽  
Author(s):  
Yoshihisa Ito ◽  
Toshihisa Osaki ◽  
Koki Kamiya ◽  
Tetsuya Yamada ◽  
Norihisa Miki ◽  
...  
Keyword(s):  
Lipid Bilayer ◽  
Pore Formation

scholarly journals DNA i-motif provides steel-like tough ends to chromosomes

2014 ◽  
Vol 1621 ◽  
pp. 135-141
Author(s):  
Raghvendra P. Singh ◽  
Ralf Blossey ◽  
Fabrizio Cleri
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Tensile Strength ◽  
Mild Steel ◽  
Sampling Methods ◽  
Persistence Length ◽  
Biological Significance ◽  
Umbrella Sampling ◽  
Structural Proteins ◽  
Bending Rigidity

ABSTRACTWe studied the structure and mechanical properties of DNA i-motif nanowires by means of molecular dynamics computer simulations. We built up to 230 nm-long nanowires, based on a repeated TC5 sequence from NMR crystallographic data, fully relaxed and equilibrated in water. The unusual C●C+ stacked structure, formed by four ssDNA strands arranged in an intercalated tetramer, is here fully characterized both statically and dynamically. By applying stretching, compression and bending deformations with the steered molecular dynamics and umbrella sampling methods, we extract the apparent Young’s and bending moduli of the nanowire, as well as estimates for the tensile strength and persistence length. According to our results, i-motif nanowires share similarities with structural proteins, as far as their tensile stiffness, but are closer to nucleic acids and flexible proteins, as far as their bending rigidity is concerned. Curiously enough, their tensile strength makes such DNA fragments tough as mild steel or a nickel alloy. Besides their yet to be clarified biological significance, i-motif nanowires may qualify as interesting candidates for nanotechnology templates, due to such outstanding mechanical properties.

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