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Membrane curvature

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https://www.readbyqxmd.com/read/29776122/glassy-phase-in-quenched-disordered-crystalline-membranes
#1
O Coquand, K Essafi, J-P Kownacki, D Mouhanna
We investigate the flat phase of D-dimensional crystalline membranes embedded in a d-dimensional space and submitted to both metric and curvature quenched disorders using a nonperturbative renormalization group approach. We identify a second-order phase transition controlled by a finite-temperature, finite-disorder fixed point unreachable within the leading order of ε=4-D and 1/d expansions. This critical point divides the flow diagram into two basins of attraction: that associated with the finite-temperature fixed point controlling the long-distance behavior of disorder-free membranes and that associated with the zero-temperature, finite-disorder fixed point...
March 2018: Physical Review. E
https://www.readbyqxmd.com/read/29775864/exogenous-hydrogen-peroxide-inhibits-primary-root-gravitropism-by-regulating-auxin-distribution-during-arabidopsis-seed-germination
#2
Lina Zhou, Hongzhou Hou, Tao Yang, Yuke Lian, Yan Sun, Zhiyuan Bian, Chongying Wang
Hydrogen peroxide (H2 O2 ) is the key factor in many physiological and metabolic processes in plants. During seed germination, exogenous H2 O2 application influences gravitropism and induces curvature of the primary root in grass pea and pea seedlings. However, it remains unclear whether and how this happens in the model plant Arabidopsis thaliana. In the present study, the effect of exogenous H2 O2 on the gravitropic response of primary roots during Arabidopsis seed germination was studied using histology and molecular biology approaches...
May 15, 2018: Plant Physiology and Biochemistry: PPB
https://www.readbyqxmd.com/read/29775478/treadmilling-analysis-reveals-new-insights-into-dynamic-ftsz-ring-architecture
#3
Diego A Ramirez-Diaz, Daniela A García-Soriano, Ana Raso, Jonas Mücksch, Mario Feingold, Germán Rivas, Petra Schwille
FtsZ, the primary protein of the bacterial Z ring guiding cell division, has been recently shown to engage in intriguing treadmilling dynamics along the circumference of the division plane. When coreconstituted in vitro with FtsA, one of its natural membrane anchors, on flat supported membranes, these proteins assemble into dynamic chiral vortices compatible with treadmilling of curved polar filaments. Replacing FtsA by a membrane-targeting sequence (mts) to FtsZ, we have discovered conditions for the formation of dynamic rings, showing that the phenomenon is intrinsic to FtsZ...
May 18, 2018: PLoS Biology
https://www.readbyqxmd.com/read/29774507/ap180-n-terminal-homology-anth-and-epsin-n-terminal-homology-enth-domains-physiological-functions-and-involvement-in-disease
#4
Sho Takatori, Taisuke Tomita
The AP180 N-terminal homology (ANTH) and Epsin N-terminal homology (ENTH) domains are crucially involved in membrane budding processes. All the ANTH/ENTH-containing proteins share the phosphoinositide-binding activity and can interact with clathrin or its related proteins via multiple binding motifs. Their function also include promotion of clathrin assembly, induction of membrane curvature, and recruitment of various effector proteins, such as those involved in membrane fission. Furthermore, they play a role in the sorting of specific cargo proteins, thereby enabling the cargos to be accurately transported and function at their appropriate locations...
May 18, 2018: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/29771630/septins-regulate-junctional-integrity-of-endothelial-monolayers
#5
Joanna Kim, John A Cooper
Junctional integrity of endothelial monolayers is crucial to control movement of molecules and cells across the endothelium. Examining the structure and dynamics of cell junctions in endothelial monolayers, we discovered a role for septins. Contacts between adjacent endothelial cells were dynamic, with protrusions extending above or below neighboring cells. VE-cadherin was present at cell junctions, with a membrane-associated layer of F-actin. Septins localized at cell-junction membranes, in patterns distinct from VE-cadherin and F-actin...
May 17, 2018: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/29768204/an-amphipathic-helix-directs-cellular-membrane-curvature-sensing-and-function-of-the-bar-domain-protein-pick1
#6
Rasmus Herlo, Viktor K Lund, Matthew D Lycas, Anna M Jansen, George Khelashvili, Rita C Andersen, Vikram Bhatia, Thomas S Pedersen, Pedro B C Albornoz, Niklaus Johner, Ina Ammendrup-Johnsen, Nikolaj R Christensen, Simon Erlendsson, Mikkel Stoklund, Jannik B Larsen, Harel Weinstein, Ole Kjærulff, Dimitrios Stamou, Ulrik Gether, Kenneth L Madsen
BAR domains are dimeric protein modules that sense, induce, and stabilize lipid membrane curvature. Here, we show that membrane curvature sensing (MCS) directs cellular localization and function of the BAR domain protein PICK1. In PICK1, and the homologous proteins ICA69 and arfaptin2, we identify an amphipathic helix N-terminal to the BAR domain that mediates MCS. Mutational disruption of the helix in PICK1 impaired MCS without affecting membrane binding per se. In insulin-producing INS-1E cells, super-resolution microscopy revealed that disruption of the helix selectively compromised PICK1 density on insulin granules of high curvature during their maturation...
May 15, 2018: Cell Reports
https://www.readbyqxmd.com/read/29760097/the-glycolipid-gm1-reshapes-asymmetric-biomembranes-and-giant-vesicles-by-curvature-generation
#7
Raktim Dasgupta, Markus S Miettinen, Nico Fricke, Reinhard Lipowsky, Rumiana Dimova
The ganglioside GM1 is present in neuronal membranes at elevated concentrations with an asymmetric spatial distribution. It is known to generate curvature and can be expected to strongly influence the neuron morphology. To elucidate these effects, we prepared giant vesicles with GM1 predominantly present in one leaflet of the membrane, mimicking the asymmetric GM1 distribution in neuronal membranes. Based on pulling inward and outward tubes, we developed a technique that allowed the direct measurement of the membrane spontaneous curvature...
May 14, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29754800/pcyt1a-regulates-phosphatidylcholine-homeostasis-from-the-inner-nuclear-membrane-in-response-to-membrane-stored-curvature-elastic-stress
#8
Afreen Haider, Yu-Chen Wei, Koini Lim, Antonio D Barbosa, Che-Hsiung Liu, Ursula Weber, Marek Mlodzik, Kadri Oras, Simon Collier, M Mahmood Hussain, Liang Dong, Satish Patel, Anna Alvarez-Guaita, Vladimir Saudek, Benjamin J Jenkins, Albert Koulman, Marcus K Dymond, Roger C Hardie, Symeon Siniossoglou, David B Savage
Cell and organelle membranes consist of a complex mixture of phospholipids (PLs) that determine their size, shape, and function. Phosphatidylcholine (PC) is the most abundant phospholipid in eukaryotic membranes, yet how cells sense and regulate its levels in vivo remains unclear. Here we show that PCYT1A, the rate-limiting enzyme of PC synthesis, is intranuclear and re-locates to the nuclear membrane in response to the need for membrane PL synthesis in yeast, fly, and mammalian cells. By aligning imaging with lipidomic analysis and data-driven modeling, we demonstrate that yeast PCYT1A membrane association correlates with membrane stored curvature elastic stress estimates...
May 7, 2018: Developmental Cell
https://www.readbyqxmd.com/read/29751591/phosphatidylcholine-membrane-fusion-is-ph-dependent
#9
Sergey A Akimov, Michael A Polynkin, Irene Jiménez-Munguía, Konstantin V Pavlov, Oleg V Batishchev
Membrane fusion mediates multiple vital processes in cell life. Specialized proteins mediate the fusion process, and a substantial part of their energy is used for topological rearrangement of the membrane lipid matrix. Therefore, the elastic parameters of lipid bilayers are of crucial importance for fusion processes and for determination of the energy barriers that have to be crossed for the process to take place. In the case of fusion of enveloped viruses (e.g., influenza) with endosomal membrane, the interacting membranes are in an acidic environment, which can affect the membrane's mechanical properties...
May 3, 2018: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29742408/membrane-bending-moduli-of-coexisting-liquid-phases-containing-transmembrane-peptide
#10
Rebecca D Usery, Thais A Enoki, Sanjula P Wickramasinghe, V P Nguyen, David G Ackerman, Denise V Greathouse, Roger E Koeppe, Francisco N Barrera, Gerald W Feigenson
A number of highly curved membranes in vivo, such as epithelial cell microvilli, have the relatively high sphingolipid content associated with "raft-like" composition. Given the much lower bending energy measured for bilayers with "nonraft" low sphingomyelin and low cholesterol content, observing high curvature for presumably more rigid compositions seems counterintuitive. To understand this behavior, we measured membrane rigidity by fluctuation analysis of giant unilamellar vesicles. We found that including a transmembrane helical GWALP peptide increases the membrane bending modulus of the liquid-disordered (Ld) phase...
May 8, 2018: Biophysical Journal
https://www.readbyqxmd.com/read/29742406/membrane-curvature-sensing-by-amphipathic-helices-insights-from-implicit-membrane-modeling
#11
Binod Nepal, John Leveritt, Themis Lazaridis
Sensing and generation of lipid membrane curvature, mediated by the binding of specific proteins onto the membrane surface, play crucial roles in cell biology. A number of mechanisms have been proposed, but the molecular understanding of these processes is incomplete. All-atom molecular dynamics simulations have offered valuable insights but are extremely demanding computationally. Implicit membrane simulations could provide a viable alternative, but current models apply only to planar membranes. In this work, the implicit membrane model 1 is extended to spherical and tubular membranes...
May 8, 2018: Biophysical Journal
https://www.readbyqxmd.com/read/29742405/molecular-dynamics-analysis-of-cardiolipin-and-monolysocardiolipin-on-bilayer-properties
#12
Kevin J Boyd, Nathan N Alder, Eric R May
The mitochondrial lipid cardiolipin (CL) contributes to the spatial protein organization and morphological character of the inner mitochondrial membrane. Monolysocardiolipin (MLCL), an intermediate species in the CL remodeling pathway, is enriched in the multisystem disease Barth syndrome. Despite the medical relevance of MLCL, a detailed molecular description that elucidates the structural and dynamic differences between CL and MLCL has not been conducted. To this end, we performed comparative atomistic molecular dynamics studies on bilayers consisting of pure CL or MLCL to elucidate similarities and differences in their molecular and bulk bilayer properties...
May 8, 2018: Biophysical Journal
https://www.readbyqxmd.com/read/29742404/bilayer-thickness-and-curvature-influence-binding-and-insertion-of-a-phlip-peptide
#13
Alexander G Karabadzhak, Dhammika Weerakkody, John Deacon, Oleg A Andreev, Yana K Reshetnyak, Donald M Engelman
The physical properties of lipid bilayers, such as curvature and fluidity, can affect the interactions of polypeptides with membranes, influencing biological events. Additionally, given the growing interest in peptide-based therapeutics, understanding the influence of membrane properties on membrane-associated peptides has potential utility. pH low insertion peptides (pHLIPs) are a family of water-soluble peptides that can insert across cell membranes in a pH-dependent manner, enabling the use of pH to follow peptide-lipid interactions...
May 8, 2018: Biophysical Journal
https://www.readbyqxmd.com/read/29741170/effects-of-cnt-size-on-the-desalination-performance-of-an-outer-wall-cnt-slit-membrane
#14
Elisa Y M Ang, Teng Yong Ng, Jingjie Yeo, Rongming Lin, Zishun Liu, K R Geethalakshmi
We investigate the effect of varying carbon nanotube (CNT) size on the desalination performance through slit confinements formed by horizontally aligned CNTs stacked on top of one another. By increasing the CNT size, the results obtained from this study indicate a corresponding increase in the water flow rate, accompanied by a slight reduction in salt rejection performance. However, due to the increase in the membrane area with CNT size, the permeability performance is observed to reduce as the CNT size increases...
May 9, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29733859/assembly-of-the-mitochondrial-cristae-organizer-mic10-is-regulated-by-mic26-mic27-antagonism-and-cardiolipin
#15
Heike Rampelt, Florian Wollweber, Carolin Gerke, Rinse de Boer, Ida J van der Klei, Maria Bohnert, Nikolaus Pfanner, Martin van der Laan
The multi-subunit mitochondrial contact site and cristae organizing system (MICOS) is a conserved protein complex of the inner mitochondrial membrane that is essential for maintenance of cristae architecture. The core subunit Mic10 forms large oligomers that build a scaffold and induce membrane curvature. The regulation of Mic10 oligomerization is poorly understood. We report that Mic26 exerts a destabilizing effect on Mic10 oligomers and thus functions in an antagonistic manner to the stabilizing subunit Mic27...
May 4, 2018: Journal of Molecular Biology
https://www.readbyqxmd.com/read/29733597/inward-budding-and-endocytosis-of-membranes-regulated-by-de-novo-designed-peptides
#16
Qiuhong Yu, Jianbo Sun, Siqi Huang, Haojing Chang, Qingwen Bai, Yong-Xiang Chen, Dehai Liang
Protein-mediated endocytosis of membrane is a key event in biological system. The mechanism, however, is still not clear. Using a de novo designed bola-typed peptide KKKLLLLLLLLKKK (K3L8K3) as a protein mimic, we studied how it induced giant unilamellar vesicle (GUV) to form inward buds or endocytosis at varying conditions. Results show that the inward budding is initiated as the charged lipids are neutralized by K3L8K3, which results in a negative spontaneous curvature. If the charged lipids has unsaturated tails, the buddings are slim fibrils, which can further wrap into a spherical structure...
May 7, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29722136/phospho-regulation-of-intrinsically-disordered-proteins-for-actin-assembly-and-endocytosis
#17
Yansong Miao, Teepiyanut Tipakornsaowapak, Liangzhen Zheng, Yuguang Mu, Eric Lewellyn
Actin filament assembly contributes to the endocytic pathway pleiotropically, with active roles in clathrin-dependent and clathrin-independent endocytosis as well as subsequent endosomal trafficking. Endocytosis comprises a series of dynamic events, including the initiation of membrane curvature, bud invagination, vesicle abscission, and subsequent vesicular transport. The ultimate success of endocytosis requires the coordinated activities of proteins that trigger actin polymerization, recruit actin-binding proteins (ABPs), and organize endocytic proteins (EPs) that promote membrane curvature through molecular crowding or scaffolding mechanisms...
May 2, 2018: FEBS Journal
https://www.readbyqxmd.com/read/29716956/cell-free-formation-and-interactome-analysis-of-caveolae
#18
WooRam Jung, Emma Sierecki, Michele Bastiani, Ailis O'Carroll, Kirill Alexandrov, James Rae, Wayne Johnston, Dominic J B Hunter, Charles Ferguson, Yann Gambin, Nicholas Ariotti, Robert G Parton
Caveolae have been linked to the regulation of signaling pathways in eukaryotic cells through direct interactions with caveolins. Here, we describe a cell-free system based on Leishmania tarentolae ( Lt ) extracts for the biogenesis of caveolae and show its use for single-molecule interaction studies. Insertion of expressed caveolin-1 (CAV1) into Lt membranes was analogous to that of caveolin in native membranes. Electron tomography showed that caveolins generate domains of precise size and curvature. Cell-free caveolae were used in quantitative assays to test the interaction of membrane-inserted caveolin with signaling proteins and to determine the stoichiometry of interactions...
May 1, 2018: Journal of Cell Biology
https://www.readbyqxmd.com/read/29716201/entropic-elasticity-based-coarse-grained-model-of-lipid-membranes
#19
Shuo Feng, Yucai Hu, Haiyi Liang
Various models for lipid bilayer membranes have been presented to investigate their morphologies. Among them, the aggressive coarse-grained models, where the membrane is represented by a single layer of particles, are computationally efficient and of practical importance for simulating membrane dynamics at the microscopic scale. In these models, soft potentials between particle pairs are used to maintain the fluidity of membranes, but the underlying mechanism of the softening requires further clarification...
April 28, 2018: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29709613/impact-of-membrane-curvature-on-amyloid-aggregation
#20
REVIEW
Mayu S Terakawa, Yuxi Lin, Misaki Kinoshita, Shingo Kanemura, Dai Itoh, Toshihiko Sugiki, Masaki Okumura, Ayyalusamy Ramamoorthy, Young-Ho Lee
The misfolding, amyloid aggregation, and fibril formation of intrinsically disordered proteins/peptides (or amyloid proteins) have been shown to cause a number of disorders. The underlying mechanisms of amyloid fibrillation and structural properties of amyloidogenic precursors, intermediates, and amyloid fibrils have been elucidated in detail; however, in-depth examinations on physiologically relevant contributing factors that induce amyloidogenesis and lead to cell death remain challenging. A large number of studies have attempted to characterize the roles of biomembranes on protein aggregation and membrane-mediated cell death by designing various membrane components, such as gangliosides, cholesterol, and other lipid compositions, and by using various membrane mimetics, including liposomes, bicelles, and different types of lipid-nanodiscs...
April 27, 2018: Biochimica et Biophysica Acta
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