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Membrane curvature

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https://www.readbyqxmd.com/read/28540958/membrane-structure-formation-induced-by-two-types-of-banana-shaped-proteins
#1
Hiroshi Noguchi, Jean-Baptiste Fournier
The assembly of banana-shaped rodlike proteins on membranes and the associated membrane shape transformations are investigated by analytical theory and coarse-grained simulations. The membrane-mediated interactions between two banana-shaped inclusions are derived theoretically using a point-like formalism based on fixed anisotropic curvatures, both for zero surface tension and for finite surface tension. On a larger scale, the interactions between the assemblies of such rodlike inclusions are determined analytically...
May 25, 2017: Soft Matter
https://www.readbyqxmd.com/read/28535145/substrate-curvature-regulates-cell-migration
#2
Xiuxiu He, Yi Jiang
Cell migration is essential in many aspects of biology. Many basic migration processes, including adhesion, membrane protrusion and tension, cytoskeletal polymerization, and contraction, have to act in concert to regulate cell migration. At the same time, substrate topography modulates these processes. In this work, we study how substrate curvature at micrometer scale regulates cell motility. We have developed a 3D mechanical model of single cell migration and simulated migration on curved substrates with different curvatures...
May 23, 2017: Physical Biology
https://www.readbyqxmd.com/read/28532212/soft-matter-in-lipid-protein-interactions
#3
Michael F Brown
Membrane lipids and cellular water (soft matter) are becoming increasingly recognized as key determinants of protein structure and function. Their influences can be ascribed to modulation of the bilayer properties or to specific binding and allosteric regulation of protein activity. In this review, we first consider hydrophobic matching of the intramembranous proteolipid boundary to explain the conformational changes and oligomeric states of proteins within the bilayer. Alternatively, membranes can be viewed as complex fluids, whose properties are linked to key biological functions...
May 22, 2017: Annual Review of Biophysics
https://www.readbyqxmd.com/read/28522140/membrane-fusion-stalks-and-lipid-rafts-a-love-hate-relationship
#4
Herre Jelger Risselada
Coarse-grained molecular dynamics simulations are applied to explore the experimentally observed ability of the liquid-ordered (lo)/liquid-disordered (ld) phase boundary to facilitate viral membrane fusion. Surprisingly, a formed fusion stalk can be both attracted (i.e., stalkophilic) and repelled (i.e., stalkophobic) by the lo/ld phase boundary. The phase boundary becomes stalkophilic if the lo phase constituents have the larger negative spontaneous curvature. In such a case, location of the highly curved stalk near the less-ordered and thus (relatively) softer boundary region becomes energetically favorable...
May 15, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28505874/general-neck-condition-for-the-limit-shape-of-budding-vesicles
#5
Pan Yang, Qiang Du, Z C Tu
The shape equation and linking conditions for a vesicle with two phase domains are derived. We refine the conjecture on the general neck condition for the limit shape of a budding vesicle proposed by Jülicher and Lipowsky [Phys. Rev. Lett. 70, 2964 (1993)PRLTAO0031-900710.1103/PhysRevLett.70.2964; Phys. Rev. E 53, 2670 (1996)1063-651X10.1103/PhysRevE.53.2670], and then we use the shape equation and linking conditions to prove that this conjecture holds not only for axisymmetric budding vesicles, but also for asymmetric ones...
April 2017: Physical Review. E
https://www.readbyqxmd.com/read/28505495/generalized-boussinesq-scriven-surface-fluid-model-with-curvature-dissipation-for-liquid-surfaces-and-membranes
#6
Oscar F Aguilar Gutierrez, Edtson E Herrera Valencia, Alejandro D Rey
Curvature dissipation is relevant in synthetic and biological processes, from fluctuations in semi-flexible polymer solutions, to buckling of liquid columns, tomembrane cell wall functioning. We present a micromechanical model of curvature dissipation relevant to fluid membranes and liquid surfaces based on a parallel surface parameterization and a stress constitutive equation appropriate for anisotropic fluids and fluid membranes.The derived model, aimed at high curvature and high rate of change of curvature in liquid surfaces and membranes, introduces additional viscous modes not included in the widely used 2D Boussinesq-Scriven rheological constitutive equation for surface fluids...
May 8, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28504295/increased-permeability-of-oxygen-atoms-through-graphene-with-ripples
#7
Guangyu He, Tao Liang, Qi Wang, Mingsheng Xu, Yingchun Liu
Graphene is an ideal membrane for selective separation because of its unique properties and single-layer structure. Considerable efforts have been made to alter the permeability of graphene. In this study, we investigate the pathways for an oxygen atom to pass through graphene sheets. We also identify the effect of the ripple's curvature in graphene sheets on the energy barrier of permeation through density functional theory calculations. Results show that oxygen atoms can easily pass through the concave side of graphene ripples with a large curvature...
May 15, 2017: Soft Matter
https://www.readbyqxmd.com/read/28500756/sphingomyelin-metabolism-controls-the-shape-and-function-of-the-golgi-cisternae
#8
Felix Campelo, Josse van Galen, Gabriele Turacchio, Seetharaman Parashuraman, Michael M Kozlov, María García-Parajo, Vivek Malhotra
The flat Golgi cisterna is a highly conserved feature of eukaryotic cells, but how is this morphology achieved and is it related to its function in cargo sorting and export? A physical model of cisterna morphology led us to propose that sphingomyelin (SM) metabolism at the trans-Golgi membranes in mammalian cells essentially controls the structural features of a Golgi cisterna by regulating its association to curvature-generating proteins. An experimental test of this hypothesis revealed that affecting SM homeostasis converted flat cisternae into highly curled membranes with a concomitant dissociation of membrane curvature-generating proteins...
May 13, 2017: ELife
https://www.readbyqxmd.com/read/28500528/bacterial-actins
#9
Izoré, Fusinita van den Ent
A diverse set of protein polymers, structurally related to actin filaments contributes to the organization of bacterial cells as cytomotive or cytoskeletal filaments. This chapter describes actin homologs encoded by bacterial chromosomes. MamK filaments, unique to magnetotactic bacteria, help establishing magnetic biological compasses by interacting with magnetosomes. Magnetosomes are intracellular membrane invaginations containing biomineralized crystals of iron oxide that are positioned by MamK along the long-axis of the cell...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28489094/theoretical-insights-into-the-mechanism-of-ferroptosis-suppression-via-inactivation-of-a-lipid-peroxide-radical-by-liproxstatin-1
#10
Xiehuang Sheng, Chao Shan, Jianbiao Liu, Jintong Yang, Bin Sun, Dezhan Chen
Ferroptosis is a recently discovered iron-dependent form of non-apoptotic cell death caused by the accumulation of membrane lipid peroxidation products, which is involved in various pathological conditions of the brain, kidney, liver and heart. A potent spiroquinoxalinamine derivative named liproxstatin-1 is discovered by high-throughput screening, which is able to suppress ferroptosis via lipid peroxide scavenging in vivo. Thus, molecular simulations, density functional theory (DFT) and variational transition-state theory with a small-curvature tunneling (SCT) coefficient are utilized to elucidate the detailed mechanisms of inactivation of a lipid peroxide radical by liproxstatin-1...
May 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28481347/membrane-curvature-regulates-ligand-specific-membrane-sorting-of-gpcrs-in-living-cells
#11
Kadla R Rosholm, Natascha Leijnse, Anna Mantsiou, Vadym Tkach, Søren L Pedersen, Volker F Wirth, Lene B Oddershede, Knud J Jensen, Karen L Martinez, Nikos S Hatzakis, Poul Martin Bendix, Andrew Callan-Jones, Dimitrios Stamou
The targeted spatial organization (sorting) of Gprotein-coupled receptors (GPCRs) is essential for their biological function and often takes place in highly curved membrane compartments such as filopodia, endocytic pits, trafficking vesicles or endosome tubules. However, the influence of geometrical membrane curvature on GPCR sorting remains unknown. Here we used fluorescence imaging to establish a quantitative correlation between membrane curvature and sorting of three prototypic class A GPCRs (the neuropeptide Y receptor Y2, the β1 adrenergic receptor and the β2 adrenergic receptor) in living cells...
May 8, 2017: Nature Chemical Biology
https://www.readbyqxmd.com/read/28475297/systems-biology-of-cellular-membranes-a-convergence-with-biophysics
#12
REVIEW
Morgan Chabanon, Jeanne C Stachowiak, Padmini Rangamani
Systems biology and systems medicine have played an important role in the last two decades in shaping our understanding of biological processes. While systems biology is synonymous with network maps and '-omics' approaches, it is not often associated with mechanical processes. Here, we make the case for considering the mechanical and geometrical aspects of biological membranes as a key step in pushing the frontiers of systems biology of cellular membranes forward. We begin by introducing the basic components of cellular membranes, and highlight their dynamical aspects...
May 5, 2017: Wiley Interdisciplinary Reviews. Systems Biology and Medicine
https://www.readbyqxmd.com/read/28473867/curvature-induced-spatial-ordering-of-composition-in-lipid-membranes
#13
Shimrit Katz, Sefi Givli
Phase segregation of membranal components, such as proteins, lipids, and cholesterols, leads to the formation of aggregates or domains that are rich in specific constituents. This process is important in the interaction of the cell with its surroundings and in determining the cell's behavior and fate. Motivated by published experiments on curvature-modulated phase separation in lipid membranes, we formulate a mathematical model aiming at studying the spatial ordering of composition in a two-component biomembrane that is subjected to a prescribed (imposed) geometry...
2017: Computational and Mathematical Methods in Medicine
https://www.readbyqxmd.com/read/28461510/golgi-apparatus-self-organizes-into-the-characteristic-shape-via-postmitotic-reassembly-dynamics
#14
Masashi Tachikawa, Atsushi Mochizuki
The Golgi apparatus is a membrane-bounded organelle with the characteristic shape of a series of stacked flat cisternae. During mitosis in mammalian cells, the Golgi apparatus is once fragmented into small vesicles and then reassembled to form the characteristic shape again in each daughter cell. The mechanism and details of the reassembly process remain elusive. Here, by the physical simulation of a coarse-grained membrane model, we reconstructed the three-dimensional morphological dynamics of the Golgi reassembly process...
May 1, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28455444/endophilin-b2-facilitates-endosome-maturation-in-response-to-growth-factor-stimulation-autophagy-induction-and-influenza-a-virus-infection
#15
Jacob M Serfass, Yoshinori Takahashi, Zhixiang Zhou, Yuka Imamura Kawasawa, Ying Liu, Nikolaos Tsotakos, Megan M Young, Zhenyuan Tang, Linlin Yang, Jennifer M Atkinson, Zissis C Chroneos, Hong-Gang Wang
Endocytosis, and the subsequent trafficking of endosomes, requires dynamic physical alterations in membrane shape that are mediated in part by endophilin proteins. The endophilin B family of proteins contains an N-terminal Bin/Amphiphysin/Rvs (N-BAR) domain that induces membrane curvature to regulate intracellular membrane dynamics. While endophilin B1 (SH3GLB1/Bif-1) is known to be involved in a number of cellular processes, including apoptosis, autophagy and endocytosis, the cellular function of endophilin B2 (SH3GLB2) is not well understood...
April 28, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28440865/generation-of-wavy-structure-on-lipid-membrane-by-peripheral-proteins-a-linear-elastic-analysis
#16
LETTER
Paritosh Mahata, Sovan Lal Das
We carry out a linear elastic analysis to study wavy structure generation on lipid membrane by peripheral membrane proteins. We model the lipid membrane as linearly elastic and anisotropic material. The hydrophobic insertion by proteins into the lipid membrane has been idealized as penetration of rigid rod-like inclusions into the membrane and the electrostatic interaction between protein and membrane has been modeled by a distributed surface traction acting on the membrane surface. With the proposed model we study curvature generation by several binding domains of peripheral membrane proteins containing BAR domains and amphipathic alpha-helices...
May 2017: FEBS Letters
https://www.readbyqxmd.com/read/28439631/polar-localization-of-mreb-actin-is-inhibited-by-anionic-phospholipids-in-the-rod-shaped-bacterium-escherichia-coli
#17
REVIEW
Daisuke Shiomi
Bacterial actin MreB is required for the maintenance of cell polarity. MreB is located underneath the cell membrane and mainly localizes at a central cylindrical part of the cell. In addition, it has recently been found that anionic phospholipids (aPLs: phosphatidylglycerol and cardiolipin) play a crucial role in excluding MreB from the cell poles. Subcellular localization of MreB is positively and negatively regulated by membrane curvature and aPLs, respectively.
April 24, 2017: Current Genetics
https://www.readbyqxmd.com/read/28424773/septins-focus-cellular-growth-for-host-infection-by-pathogenic-fungi
#18
REVIEW
Michelle Momany, Nicholas J Talbot
One of the key challenges faced by microbial pathogens is invasion of host tissue. Fungal pathogens adopt a number of distinct strategies to overcome host cell defenses, including the development of specialized infection structures, the secretion of proteins that manipulate host responses or cellular organization, and the ability to facilitate their own uptake by phagocytic mechanisms. Key to many of these adaptations is the considerable morphogenetic plasticity displayed by pathogenic species. Fungal pathogens can, for example, shift their growth habit between non-polarized spores, or yeast-like cells, and highly polarized hyphal filaments...
2017: Frontiers in Cell and Developmental Biology
https://www.readbyqxmd.com/read/28417957/attractive-force-driven-superhardening-of-graphene-membranes-as-a-pin-point-breaking-of-continuum-mechanics
#19
Makoto Ashino, Roland Wiesendanger
Bending at the nanometre scale can substantially modify the mechanical, chemical and electronic properties of graphene membranes. The subsequent response of chemical bonds leads to deviations from plate idealisation in continuum mechanics. However, those phenomena have thus far been investigated exclusively by measuring the electronic properties of graphene deformed by compressing and stretching with local-probe techniques. Here, we report that the interatomic-attractive forces applied on the convexly-curved graphene by the probe tip give rise to a pin-point breaking of the plate idealisation in the continuum mechanics, facilitating atomically-localised enhancements in its chemical reactivity and mechanical strength...
April 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28411214/achiral-symmetry-breaking-and-positive-gaussian-modulus-lead-to-scalloped-colloidal-membranes
#20
Thomas Gibaud, C Nadir Kaplan, Prerna Sharma, Mark J Zakhary, Andrew Ward, Rudolf Oldenbourg, Robert B Meyer, Randall D Kamien, Thomas R Powers, Zvonimir Dogic
In the presence of a nonadsorbing polymer, monodisperse rod-like particles assemble into colloidal membranes, which are one-rod-length-thick liquid-like monolayers of aligned rods. Unlike 3D edgeless bilayer vesicles, colloidal monolayer membranes form open structures with an exposed edge, thus presenting an opportunity to study elasticity of fluid sheets. Membranes assembled from single-component chiral rods form flat disks with uniform edge twist. In comparison, membranes composed of a mixture of rods with opposite chiralities can have the edge twist of either handedness...
April 25, 2017: Proceedings of the National Academy of Sciences of the United States of America
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