scholarly journals Lipid membrane-mediated attraction between curvature inducing objects

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Casper van der Wel ◽  
Afshin Vahid ◽  
Anđela Šarić ◽  
Timon Idema ◽  
Doris Heinrich ◽  
...  
Keyword(s):  
Colloidal Particles ◽  
Lipid Membrane ◽  
Numerical Study ◽  
Particle Diameter ◽  
Interaction Force ◽  
Membrane Curvature ◽  
Coarse Grained ◽  
Cellular Transport ◽  
Curvature Energy ◽  
Membrane Deformations

Abstract The interplay of membrane proteins is vital for many biological processes, such as cellular transport, cell division, and signal transduction between nerve cells. Theoretical considerations have led to the idea that the membrane itself mediates protein self-organization in these processes through minimization of membrane curvature energy. Here, we present a combined experimental and numerical study in which we quantify these interactions directly for the first time. In our experimental model system we control the deformation of a lipid membrane by adhering colloidal particles. Using confocal microscopy, we establish that these membrane deformations cause an attractive interaction force leading to reversible binding. The attraction extends over 2.5 times the particle diameter and has a strength of three times the thermal energy (−3.3 kBT). Coarse-grained Monte-Carlo simulations of the system are in excellent agreement with the experimental results and prove that the measured interaction is independent of length scale. Our combined experimental and numerical results reveal membrane curvature as a common physical origin for interactions between any membrane-deforming objects, from nanometre-sized proteins to micrometre-sized particles.

Numerical Study on Electrokinetic Interaction Between a Pair of Cylindrical Colloidal Particles

2009 ◽  
Author(s):  
Dolfred Vijay Fernandes ◽  
Sangmo Kang ◽  
Yong Kweon Suh
Keyword(s):  
Flow Field ◽  
Electric Field ◽  
Colloidal Particles ◽  
Stokes Equations ◽  
Separation Efficiency ◽  
Numerical Study ◽  
Interaction Force ◽  
Surface Element ◽  
Immersed Boundary ◽  
Interaction Forces

Electrophoresis is the motion of dispersed particles relative to a fluid under the influence of an electric field. Presently this phenomenon of electrokinetics is widely used in biotechnology for the separation of proteins, sequencing of polypeptide chains etc. The separation efficiency of these biomolecules is affected by their aggregation. Thus it is important to study the interaction forces between the molecules. In this study we calculate the electrophoretic motion of a pair of colloidal particles under axial electric field. The hydrodynamic and electric double layer (EDL) interaction forces are calculated numerically. The EDL interaction force is calculated from electric field distribution around the particle using Maxwell stress tensor and the hydrodynamic force is calculated from the flow field obtained from the solution of Stokes equations. The continuous forcing approach of immersed boundary method is used to obtain flow field around the moving particles. The EDL distribution around the particles is obtained by solving Poisson-Nernst-Planck (PNP) equations on a hybrid grid system. The EDL interaction force calculated from numerical solution is compared with the one obtained from surface element integration (SEI) method.

scholarly journals Curvature induction and sensing of the F-BAR protein Pacsin1 on lipid membranes via molecular dynamics simulations

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Md. Iqbal Mahmood ◽  
Hiroshi Noguchi ◽  
Kei-ichi Okazaki
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Lipid Membranes ◽  
Lipid Membrane ◽  
Complex Structure ◽  
Membrane Curvature ◽  
Coarse Grained ◽  
Lateral Interaction ◽  
Bar Domain ◽  
Dynamics Simulations

Abstract F-Bin/Amphiphysin/Rvs (F-BAR) domain proteins play essential roles in biological processes that involve membrane remodelling, such as endocytosis and exocytosis. It has been shown that such proteins transform the lipid membrane into tubes. Notably, Pacsin1 from the Pacsin/Syndapin subfamily has the ability to transform the membrane into various morphologies: striated tubes, featureless wide and thin tubes, and pearling vesicles. The molecular mechanism of this interesting ability remains elusive. In this study, we performed all-atom (AA) and coarse-grained (CG) molecular dynamics simulations to investigate the curvature induction and sensing mechanisms of Pacsin1 on a membrane. From AA simulations, we show that Pacsin1 has internal structural flexibility. In CG simulations with parameters tuned from the AA simulations, spontaneous assembly of two Pacsin1 dimers through lateral interaction is observed. Based on the complex structure, we show that the regularly assembled Pacsin1 dimers bend a tensionless membrane. We also show that a single Pacsin1 dimer senses the membrane curvature, binding to a buckled membrane with a preferred curvature. These results provide molecular insights into polymorphic membrane remodelling.

scholarly journals Entropic forces drive clustering and spatial localization of influenza A M2 during viral budding

2018 ◽  
Vol 115 (37) ◽  
pp. E8595-E8603 ◽  
Author(s):  
Jesper J. Madsen ◽  
John M. A. Grime ◽  
Jeremy S. Rossman ◽  
Gregory A. Voth
Keyword(s):  
Host Cell ◽  
Influenza A ◽  
Lipid Membrane ◽  
Transmembrane Protein ◽  
Membrane Curvature ◽  
Coarse Grained ◽  
Membrane Remodeling ◽  
Viral Budding ◽  
Virion Release ◽  
Liquid Ordered

The influenza A matrix 2 (M2) transmembrane protein facilitates virion release from the infected host cell. In particular, M2 plays a role in the induction of membrane curvature and/or in the scission process whereby the envelope is cut upon virion release. Here we show using coarse-grained computer simulations that various M2 assembly geometries emerge due to an entropic driving force, resulting in compact clusters or linearly extended aggregates as a direct consequence of the lateral membrane stresses. Conditions under which these protein assemblies will cause the lipid membrane to curve are explored, and we predict that a critical cluster size is required for this to happen. We go on to demonstrate that under the stress conditions taking place in the cellular membrane as it undergoes large-scale membrane remodeling, the M2 protein will, in principle, be able to both contribute to curvature induction and sense curvature to line up in manifolds where local membrane line tension is high. M2 is found to exhibit linactant behavior in liquid-disordered–liquid-ordered phase-separated lipid mixtures and to be excluded from the liquid-ordered phase, in near-quantitative agreement with experimental observations. Our findings support a role for M2 in membrane remodeling during influenza viral budding both as an inducer and a sensor of membrane curvature, and they suggest a mechanism by which localization of M2 can occur as the virion assembles and releases from the host cell, independent of how the membrane curvature is produced.

scholarly journals Effect of malaria parasite shape on its alignment at erythrocyte membrane

2021 ◽  
Author(s):  
Anil K Dasanna ◽  
Sebastian Hillringhaus ◽  
Gerhard Gompper ◽  
Dmitry A Fedosov
Keyword(s):  
Spherical Shape ◽  
Coarse Grained ◽  
Local Curvature ◽  
Stochastic Nature ◽  
Rbc Membrane ◽  
Aspect Ratios ◽  
Strong Adhesion ◽  
Alignment Process ◽  
Pointed End ◽  
Membrane Deformations

During the blood stage of malaria pathogenesis, parasites invade healthy red blood cells (RBC) to multiply inside the host and evade the immune response. When attached to RBC, the parasite first has to align its apex with the membrane for a successful invasion. Since the parasite's apex sits at the pointed end of an oval (egg-like) shape with a large local curvature, apical alignment is in general an energetically un-favorable process. Previously, using coarse-grained mesoscopic simulations, we have shown that optimal alignment time is achieved due to RBC membrane deformation and the stochastic nature of bond-based interactions between the parasite and RBC membrane (Hillringhaus et al., 2020). Here, we demonstrate that the parasite's shape has a prominent effect on the alignment process. The alignment times of spherical parasites for intermediate and large bond off-rates (or weak membrane-parasite interactions) are found to be close to those of an egg-like shape. However, for small bond off-rates (or strong adhesion and large membrane deformations), the alignment time for a spherical shape increases drastically. Parasite shapes with large aspect ratios such as oblate and long prolate ellipsoids are found to exhibit very long alignment times in comparison to the egg-like shape. At a stiffened RBC, spherical parasite aligns faster than any other investigated shapes. This study shows that the original egg-like shape performs not worse for parasite alignment than other considered shapes, but is more robust with respect to different adhesion interactions and RBC membrane rigidities.

Measurement of the capillary interaction force between Janus colloidal particles trapped at a flat air/water interface

Soft Matter ◽  
2020 ◽  
Vol 16 (25) ◽  
pp. 5910-5914
Author(s):  
Virginia Carrasco-Fadanelli ◽  
Rolando Castillo
Keyword(s):  
Colloidal Particles ◽  
Power Laws ◽  
Interaction Force ◽  
Janus Particles ◽  
Water Interface ◽  
Air Water Interface

The capillary interaction force between spherical Janus particles trapped at the air–water interface is a sum of power laws.

scholarly journals Numerical Study of the Dynamic Compaction Process considering the Phenomenon of Particle Breakage

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Xi Li ◽  
Jing Li ◽  
Xinyan Ma ◽  
Jidong Teng ◽  
Sheng Zhang
Keyword(s):  
Numerical Study ◽  
High Energy ◽  
Particle Breakage ◽  
Dynamic Compaction ◽  
Coarse Grained ◽  
Impact Stress ◽  
Logarithmic Curve ◽  
Before And After ◽  
Soil Foundation ◽  
Overlapping Method

Dynamic compaction (DC) is commonly used to strengthen the coarse grained soil foundation, where particle breakage of coarse soils is unavoidable under high-energy impacts. In this paper, a novel method of modeling DC progress was developed, which can realize particle breakage by impact stress. A particle failure criterion of critical stress is first employed. The “population balance” between particles before and after crushing is guaranteed by the overlapping method. The performance of the DC model is successfully validated against literature data. A series of DC tests were then carried out. The effect of particle breakage on key parameters of DC including crater depth and impact stress was discussed. Besides, it is observed that the relationship between breakage amount and tamping times can be expressed by a logarithmic curve. The present method will contribute to a better understanding of DC and benefit further research on the macro-micro mechanism of DC.

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