Calculation of membrane bending rigidity using field-theoretic umbrella sampling

2015 ◽  
Vol 143 (24) ◽  
pp. 243155 ◽  
Author(s):  
Y. G. Smirnova ◽  
M. Müller
Keyword(s):  
Umbrella Sampling ◽  
Bending Rigidity ◽  
Membrane Bending

scholarly journals Impact of Sterol Tilt on Membrane Bending Rigidity in Cholesterol and 7DHC-Containing DMPC Membrane

2012 ◽  
Vol 102 (3) ◽  
pp. 413a
Author(s):  
George Khelashvili ◽  
Michael Rappolt ◽  
See-Wing Chiu ◽  
Georg Pabst ◽  
Daniel Harries
Keyword(s):  
Bending Rigidity ◽  
Membrane Bending ◽  
Dmpc Membrane

scholarly journals Membrane stiffness is a key determinant of E coli MscS channel mechanosensitivity

2019 ◽  
Author(s):  
Feng Xue ◽  
Charles D. Cox ◽  
Navid Bavi ◽  
Paul R Rohde ◽  
Yoshitaka Nakayama ◽  
...  
Keyword(s):  
Response Curve ◽  
Membrane Lipids ◽  
Bending Rigidity ◽  
Rightward Shift ◽  
E Coli ◽  
Tension Response ◽  
Global Properties ◽  
Membrane Stiffness ◽  
Membrane Bending ◽  
Branched Chain

AbstractProkaryotic mechanosensitive (MS) channels have an intimate relationship with membrane lipids. Membrane lipids may influence channel activity by directly interacting with bacterial MS channels or by influencing the global properties of the membrane such as area stretch and bending moduli. Previous work has implicated membrane stiffness as a key determinant of the mechanosensitivity of E. coli (Ec)MscS. Here we systematically tested this hypothesis using patch fluorometry of azolectin liposomes doped with lipids of increasing area stretch moduli. Increasing DOPE content of azolectin liposomes causes a rightward shift in the tension response curve of EcMscS. These rightward shifts are further magnified by the addition of stiffer forms of PE such as the branched chain lipid DPhPE and the fully saturated lipid DSPE. Furthermore, a comparison of the branched chain lipid DPhPC to the stiffer DPhPE showed a rightward shift in the tension response curve in the presence of the stiffer DPhPE. We show that these changes are not due to changes in membrane bending rigidity as the tension threshold of EcMscS in membranes doped with PC18:1 and PC18:3 are the same, despite a two-fold difference in their bending rigidity. We also show that after prolonged pressure application sudden removal of force in softer membranes causes a rebound reactivation of EcMscS and we discuss the relevance of this phenomenon to bacterial osmoregulation. Collectively, our data demonstrate that membrane stiffness is a key determinant of the mechanosensitivity of EcMscS.

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.

EFFECT OF MEMBRANE BENDING STIFFNESS ON THE DEFORMATION OF ELASTIC CAPSULES IN EXTENSIONAL FLOW: A LATTICE BOLTZMANN STUDY

2007 ◽  
Vol 18 (08) ◽  
pp. 1277-1291 ◽  
Author(s):  
Y. SUI ◽  
Y. T. CHEW ◽  
P. ROY ◽  
H. T. LOW
Keyword(s):  
Lattice Boltzmann ◽  
Present Model ◽  
Extensional Flow ◽  
Bending Stiffness ◽  
Immersed Boundary ◽  
Two Dimensional ◽  
Bending Rigidity ◽  
Elastic Membranes ◽  
Membrane Bending ◽  
Boltzmann Method

The transient deformation of liquid capsules enclosed by elastic membranes in two-dimensional extensional flow is studied numerically, using an improved immersed boundary-lattice Boltzmann method. The purpose of the present study is to investigate the effect of interfacial bending stiffness on the deformation of such capsules, under the subcritical elasticity capillary number conditions. The present model can simulate flow-induced deformation of capsules with arbitrary resting shapes (concerning the in-plane tension) and bending-free configurations. The deformation of capsules with initially circular, elliptical, and biconcave resting shapes was investigated in the present study; the capsules' bending-free configurations were considered as either circular shapes or their initially resting shapes. The results show that for capsules with bending-free configuration as circles, membrane bending rigidity has significant rounding effect on the steady deformed profiles. For elliptical and biconcave capsules with resting shapes as the bending-free configurations, it is found that with the bending stiffness increasing, the capsules' steady shapes are more akin to their initial shapes.

Molecular Origin of Model Membrane Bending Rigidity

2007 ◽  
Vol 98 (25) ◽  
Author(s):  
Erol Kurtisovski ◽  
Nicolas Taulier ◽  
Raymond Ober ◽  
Marcel Waks ◽  
Wladimir Urbach
Keyword(s):  
Model Membrane ◽  
Bending Rigidity ◽  
Molecular Origin ◽  
Membrane Bending

scholarly journals Effect of Bilayer Thickness on Membrane Bending Rigidity

Langmuir ◽  
2004 ◽  
Vol 20 (3) ◽  
pp. 540-543 ◽  
Author(s):  
H. Bermúdez ◽  
D. A. Hammer ◽  
D. E. Discher
Keyword(s):  
Bending Rigidity ◽  
Bilayer Thickness ◽  
Membrane Bending

scholarly journals Regulation of the membrane wrapping transition of a cylindrical target by cytoskeleton adhesion

2014 ◽  
Vol 11 (100) ◽  
pp. 20140769 ◽  
Author(s):  
Seyed Mahmoud Hashemi ◽  
Pierre Sens ◽  
Farshid Mohammad-Rafiee
Keyword(s):  
Cell Membrane ◽  
Elastic Deformation ◽  
Actin Polymerization ◽  
Force Balance ◽  
Bending Rigidity ◽  
External Objects ◽  
Cylindrical Target ◽  
Membrane Bending ◽  
Target Binding ◽  
Active Force Generation

The adsorption of external objects to the cell membrane often triggers cellular responses involving large deformations. In phagocytosis, upon contact with the target, the cell creates large extensions that wrap around the target and ultimately lead to its engulfment. Although active force generation, in particular by actin polymerization, is required for completion of this process, the elastic deformation of the cell membrane upon adhesion to an external object might play an important part in its initiation. In this paper, the elastic deformation of a bilayer owing to the binding of a cylindrical object is studied, taking into account the membrane bending rigidity and the surface tension, the membrane adhesion to both the external target and inner cytoskeleton. The problem is studied within the framework of the Helfrich–Hamiltonian and using force balance relations and the proper boundary conditions that are related to the adhesion energy coefficients. It is shown that membrane wrapping around the target may be a continuous or abrupt transition upon increasing the target binding energy, depending on the value of the parameter. The degree of wrapping and the shape of the membrane in the vicinity of the object are computed numerically, and analytical expressions are given for the boundaries separating the different wrapping regimes in the parameter space.

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