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Membrane curvature

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https://www.readbyqxmd.com/read/28926699/effects-of-high-pressure-on-phospholipid-bilayers
#1
Wei Ding, Michail Palaiokostas, Ganesh Shahane, Wen Wang, Mario Orsi
The response of lipid membranes to changes in external pressure is important for many biological processes, and it can also be exploited for technological applications. In this work, we employ all-atom molecular dynamics simulations to characterize the changes in the physical properties of phospholipid bilayers brought about by high pressure (1000 bar). In particular, we study how the response differs, in relation to different chain unsaturation levels, by comparing mono-unsaturated 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) and bi-unsaturated dioleoyl-phosphatidylcholine (DOPC) bilayers...
September 19, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28923975/control-of-actin-polymerization-via-the-coincidence-of-phosphoinositides-and-high-membrane-curvature
#2
Frederic Daste, Astrid Walrant, Mikkel R Holst, Jonathan R Gadsby, Julia Mason, Ji-Eun Lee, Daniel Brook, Marcel Mettlen, Elin Larsson, Steven F Lee, Richard Lundmark, Jennifer L Gallop
The conditional use of actin during clathrin-mediated endocytosis in mammalian cells suggests that the cell controls whether and how actin is used. Using a combination of biochemical reconstitution and mammalian cell culture, we elucidate a mechanism by which the coincidence of PI(4,5)P2 and PI(3)P in a curved vesicle triggers actin polymerization. At clathrin-coated pits, PI(3)P is produced by the INPP4A hydrolysis of PI(3,4)P2, and this is necessary for actin-driven endocytosis. Both Cdc42⋅guanosine triphosphate and SNX9 activate N-WASP-WIP- and Arp2/3-mediated actin nucleation...
September 18, 2017: Journal of Cell Biology
https://www.readbyqxmd.com/read/28910109/membrane-tubulation-in-lipid-vesicles-triggered-by-the-local-application-of-calcium-ions
#3
Baharan Ali Doosti, Weria Pezeshkian, Dennis Skjøth Bruhn, John Hjort Ipsen, Himanshu Khandelia, Gavin D M Jeffries, Tatsiana Lobovkina
Experimental and theoretical studies on ion-lipid interactions, predict that binding of calcium ions to cell membranes leads to macroscopic mechanical effects and membrane remodeling. Herein, we provide experimental evidence that a point-source of Ca2+ acting upon a negatively charged membrane, generates spontaneous curvature and triggers the formation of tubular protrusions that point away from the ion source. This behavior is rationalized by strong binding of the divalent cations to the surface of the charged bilayer which effectively neutralizes the surface charge density of outer leaflet of the bilayer...
September 14, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28900187/electrostatics-of-non-neutral-biological-microdomains
#4
J Cartailler, Z Schuss, D Holcman
Voltage and charge distributions in cellular microdomains regulate communications, excitability, and signal transduction. We report here new electrical laws in a biological cell, which follow from a nonlinear electro-diffusion model. These newly discovered laws derive from the geometrical cell-membrane properties, such as membrane curvature, volume, and surface area. The electro-diffusion laws can now be used to predict and interpret voltage distribution in cellular microdomains such as synapses, dendritic spine, cilia and more...
September 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28893863/bin1-directly-remodels-actin-dynamics-through-its-bar-domain
#5
Nina M Dräger, Eliana Nachman, Moritz Winterhoff, Stefan Brühmann, Pranav Shah, Taxiarchis Katsinelos, Steeve Boulant, Aurelio A Teleman, Jan Faix, Thomas R Jahn
Endocytic processes are facilitated by both curvature-generating BAR-domain proteins and the coordinated polymerization of actin filaments. Under physiological conditions, the N-BAR protein Bin1 has been shown to sense and curve membranes in a variety of cellular processes. Recent studies have identified Bin1 as a risk factor for Alzheimer's disease, although its possible pathological function in neurodegeneration is currently unknown. Here, we report that Bin1 not only shapes membranes, but is also directly involved in actin binding through its BAR domain...
September 11, 2017: EMBO Reports
https://www.readbyqxmd.com/read/28888369/structure-analysis-of-the-membrane-bound-dermcidin-derived-peptide-ssl-25-from-human-sweat
#6
Philipp Mühlhäuser, Parvesh Wadhwani, Erik Strandberg, Jochen Bürck, Anne S Ulrich
SSL-25 (SSLLEKGLDGAKKAVGGLGKLGKDA) is one of the shortest peptides present in human sweat and is produced after the proteolytic processing of the parent peptide dermcidin. Both peptides are reported to have antimicrobial function. To determine the structure of SSL-25 in lipid bilayers, a series of (19)F-labeled SSL-25 analogs were synthesized. Circular dichroism (CD) analysis showed that SSL-25 and all of its analogs formed α-helices in the presence of lipid vesicles, thus allowing a detailed analysis via oriented CD and solid-state NMR...
September 6, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28885628/fluctuation-tension-and-shape-transition-of-vesicles-renormalisation-calculations-and-monte-carlo-simulations
#7
Guillaume Gueguen, Nicolas Destainville, Manoel Manghi
It has been known for long that the fluctuation surface tension of membranes r, computed from the height fluctuation spectrum, is not equal to the bare surface tension σ, which is introduced in the theory either as a Lagrange multiplier to conserve the total membrane area or as an external constraint. In this work we relate these two surface tensions both analytically and numerically. They are also compared to the Laplace tension γ, and the mechanical frame tension τ. Using the Helfrich model and one-loop renormalisation calculations, we obtain, in addition to the effective bending modulus κeff, a new expression for the effective surface tension σeff = σ - εkBT/(2ap) where kBT is the thermal energy, ap the projected cut-off area, and ε = 3 or 1 according to the allowed configurations that keep either the projected area or the total area constant...
September 20, 2017: Soft Matter
https://www.readbyqxmd.com/read/28878347/targeting-bacterial-cardiolipin-enriched-microdomains-an-antimicrobial-strategy-used-by-amphiphilic-aminoglycoside-antibiotics
#8
Micheline El Khoury, Jitendriya Swain, Guillaume Sautrey, Louis Zimmermann, Patrick Van Der Smissen, Jean-Luc Décout, Marie-Paule Mingeot-Leclercq
Some bacterial proteins involved in cell division and oxidative phosphorylation are tightly bound to cardiolipin. Cardiolipin is a non-bilayer anionic phospholipid found in bacterial inner membrane. It forms lipid microdomains located at the cell poles and division plane. Mechanisms by which microdomains are affected by membrane-acting antibiotics and the impact of these alterations on membrane properties and protein functions remain unclear. In this study, we demonstrated cardiolipin relocation and clustering as a result of exposure to a cardiolipin-acting amphiphilic aminoglycoside antibiotic, the 3',6-dinonyl neamine...
September 6, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28863515/novel-tilt-curvature-coupling-in-lipid-membranes
#9
M Mert Terzi, Markus Deserno
On mesoscopic scales, lipid membranes are well described by continuum theories whose main ingredients are the curvature of a membrane's reference surface and the tilt of its lipid constituents. In particular, Hamm and Kozlov [Eur. Phys. J. E 3, 323 (2000)] have shown how to systematically derive such a tilt-curvature Hamiltonian based on the elementary assumption of a thin fluid elastic sheet experiencing internal lateral pre-stress. Performing a dimensional reduction, they not only derive the basic form of the effective surface Hamiltonian but also express its emergent elastic couplings as trans-membrane moments of lower-level material parameters...
August 28, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28854360/spatiotemporal-control-of-lipid-conversion-actin-based-mechanical-forces-and-curvature-sensors-during-clathrin-ap-1-coated-vesicle-biogenesis
#10
Mihaela Anitei, Christoph Stange, Cornelia Czupalla, Christian Niehage, Kai Schuhmann, Pia Sala, Aleksander Czogalla, Theresia Pursche, Ünal Coskun, Andrej Shevchenko, Bernard Hoflack
Clathrin/adaptor protein-1-coated carriers connect the secretory and the endocytic pathways. Carrier biogenesis relies on distinct protein networks changing membrane shape at the trans-Golgi network, each regulating coat assembly, F-actin-based mechanical forces, or the biophysical properties of lipid bilayers. How these different hubs are spatiotemporally coordinated remains largely unknown. Using in vitro reconstitution systems, quantitative proteomics, and lipidomics, as well as in vivo cell-based assays, we characterize the protein networks controlling membrane lipid composition, membrane shape, and carrier scission...
August 29, 2017: Cell Reports
https://www.readbyqxmd.com/read/28845423/cristae-architecture-is-determined-by-an-interplay-of-the-micos-complex-and-the-f1fo-atp-synthase-via-mic27-and-mic10
#11
Katharina Eydt, Karen M Davies, Christina Behrendt, Ilka Wittig, Andreas S Reichert
The inner boundary and the cristae membrane are connected by pore-like structures termed crista junctions (CJs). The MICOS complex is required for CJ formation and enriched at CJs. Here, we address the roles of the MICOS subunits Mic27 and Mic10. We observe a positive genetic interaction between Mic27 and Mic60 and deletion of Mic27 results in impaired formation of CJs and altered cristae membrane curvature. Mic27 acts in an antagonistic manner to Mic60 as it promotes oligomerization of the F1FO-ATP synthase and partially restores CJ formation in cells lacking Mic60...
July 20, 2017: Microbial Cell
https://www.readbyqxmd.com/read/28835547/ifitm3-requires-an-amphipathic-helix-for-antiviral-activity
#12
Nicholas M Chesarino, Alex A Compton, Temet M McMichael, Adam D Kenney, Lizhi Zhang, Victoria Soewarna, Matthew Davis, Olivier Schwartz, Jacob S Yount
Interferon-induced transmembrane protein 3 (IFITM3) is a cellular factor that blocks virus fusion with cell membranes. IFITM3 has been suggested to alter membrane curvature and fluidity, though its exact mechanism of action is unclear. Using a bioinformatic approach, we predict IFITM3 secondary structures and identify a highly conserved, short amphipathic helix within a hydrophobic region of IFITM3 previously thought to be a transmembrane domain. Consistent with the known ability of amphipathic helices to alter membrane properties, we show that this helix and its amphipathicity are required for the IFITM3-dependent inhibition of influenza virus, Zika virus, vesicular stomatitis virus, Ebola virus, and human immunodeficiency virus infections...
August 23, 2017: EMBO Reports
https://www.readbyqxmd.com/read/28829131/lipid-phase-control-and-secondary-structure-of-viral-fusion-peptides-anchored-in-monoolein-membranes
#13
Artem Levin, Christoph Jeworrek, Roland Winter, Katrin Weise, Claus Czeslik
The fusion of lipid membranes involves major changes of the membrane curvatures and is mediated by fusion proteins that bind to the lipid membranes. For a better understanding of the way fusion proteins steer this process, we have studied the interaction of two different viral fusion peptides, HA2-FP and TBEV-FP, with monoolein mesophases as a function of temperature and pressure at limited hydration. The fusion peptides are derived from the influenza virus hemagglutinin fusion protein (HA2-FP) and from the tick-borne encephalitis virus envelope glycoprotein E (TBEV-FP)...
August 31, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28808346/evidence-that-listeria-innocua-modulates-its-membrane-s-stored-curvature-elastic-stress-but-not-fluidity-through-the-cell-cycle
#14
Samuel Furse, Martin Jakubec, Frode Rise, Huw E Williams, Catherine E D Rees, Øyvind Halskau
This paper reports that the abundances of endogenous cardiolipin and phosphatidylethanolamine halve during elongation of the Gram-positive bacterium Listeria innocua. The lyotropic phase behaviour of model lipid systems that describe these modulations in lipid composition indicate that the average stored curvature elastic stress of the membrane is reduced on elongation of the cell, while the fluidity appears to be maintained. These findings suggest that phospholipid metabolism is linked to the cell cycle and that changes in membrane composition can facilitate passage to the succeding stage of the cell cycle...
August 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28805387/polymyxin-binding-to-the-bacterial-outer-membrane-reveals-cation-displacement-and-increasing-membrane-curvature-in-susceptible-but-not-in-resistant-lipopolysaccharide-chemotypes
#15
Denys E S Santos, Laércio Pol-Fachin, Roberto D Lins, Thereza A Soares
Lipid-A is the causative agent of Gram-negative sepsis and is responsible for an increasingly high mortality rate among hospitalized patients. Compounds that bind Lipid-A can limit this inflammatory process. The cationic antimicrobial peptide polymyxin B (Pmx-B) is one of the simplest molecules capable of selectively binding to Lipid-A and may serve as a model for further development of Lipid-A binding agents. Gram-negative bacteria resistance to Pmx-B relies on the upregulation of a number of regulatory systems, which promote chemical modifications of the lipopolysaccharide (LPS) structure and leads to major changes in the physical-chemical properties of the outer membrane...
August 25, 2017: Journal of Chemical Information and Modeling
https://www.readbyqxmd.com/read/28804520/fast-simulation-of-lipid-vesicle-deformation-using-spherical-harmonic-approximation
#16
Michael Mikucki, Yongcheng Zhou
Lipid vesicles appear ubiquitously in biological systems. Understanding how the mechanical and intermolecular interactions deform vesicle membranes is a fundamental question in biophysics. In this article we develop a fast algorithm to compute the surface configurations of lipid vesicles by introducing surface harmonic functions to approximate the membrane surface. This parameterization allows an analytical computation of the membrane curvature energy and its gradient for the efficient minimization of the curvature energy using a nonlinear conjugate gradient method...
January 2017: Communications in Computational Physics
https://www.readbyqxmd.com/read/28804159/geodesic-curvature-driven-surface-microdomain-formation
#17
Melissa R Adkins, Y C Zhou
Lipid bilayer membranes are not uniform and clusters of lipids in a more ordered state exist within the generally disorder lipid milieu of the membrane. These clusters of ordered lipids microdomains are now referred to as lipid rafts. Recent reports attribute the formation of these microdomains to the geometrical and molecular mechanical mismatch of lipids of different species on the boundary. Here we introduce the geodesic curvature to characterize the geometry of the domain boundary, and develop a geodesic curvature energy model to describe the formation of these microdomains as a result of energy minimization...
September 15, 2017: Journal of Computational Physics
https://www.readbyqxmd.com/read/28794948/glucosomes-glycosylated-vesicle-in-vesicle-aggregates-in-water-from-ph-responsive-microbial-glycolipid
#18
Niki Baccile, Patrick Le Griel, Sylvain Prévost, Bernd Everaert, Inge N A Van Bogaert, Sophie Roelants, Wim Soetaert
Vesicle-in-vesicle self-assembled containers, or vesosomes, are promising alternatives to liposomes because of their possible hierarchical encapsulation and high stability. We report herein the first example of sugar-based vesicles-in-vesicles, which we baptize glucosomes. These were prepared by using a natural microbial glycolipid (branched C22 sophorolipid) extracted from the culture medium of the yeast Pseudohyphozyma bogoriensis. Glucosomes spontaneously formed in water between pH 6 and pH 4 at room temperature, without the requirement of any additive...
August 2017: ChemistryOpen
https://www.readbyqxmd.com/read/28794042/palmitoylation-contributes-to-membrane-curvature-in-influenza-a-virus-assembly-and-hemagglutinin-mediated-membrane-fusion
#19
Petr Chlanda, Elena Mekhedov, Hang Waters, Alexander Sodt, Cindi Schwartz, Vinod Nair, Paul S Blank, Joshua Zimmerberg
The highly conserved cytoplasmic tail of influenza virus glycoprotein hemagglutinin (HA) contains three cysteines, post-translationally modified by covalently bound fatty acids. While viral HA acylation is crucial in virus replication, its physico-chemical role is unknown. We used virus-like particles (VLP) to study the effect of acylation on morphology, protein incorporation, lipid composition, and membrane fusion. De-acylation interrupted HA-M1 interactions since de-acylated mutant HA fail to incorporate an M1 layer within spheroidal VLP, and filamentous particles incorporated increased numbers of neuraminidase (NA)...
August 9, 2017: Journal of Virology
https://www.readbyqxmd.com/read/28790210/membrane-distribution-of-the-pseudomonas-quinolone-signal-modulates-outer-membrane-vesicle-production-in-pseudomonas%C3%A2-aeruginosa
#20
Catalina Florez, Julie E Raab, Adam C Cooke, Jeffrey W Schertzer
The Pseudomonas quinolone signal (PQS) is an important quorum-sensing molecule in Pseudomonas aeruginosa that also mediates its own packaging and transport by stimulating outer membrane vesicle (OMV) formation. Because OMVs have been implicated in many virulence-associated behaviors, it is critical that we understand how they are formed. Our group proposed the bilayer-couple model for OMV biogenesis, where PQS intercalates into the outer membrane, causing expansion of the outer leaflet and consequently inducing curvature...
August 8, 2017: MBio
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