Stalk structures in lipid bilayer fusion studied by x-ray diffraction

Aeffner, Sebastian

doi:10.17875/gup2012-81

Cited by 9 publications

(26 citation statements)

References 128 publications

(286 reference statements)

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“…The repulsion pressure P(d w ) h Àg 0 (d w ) can then be obtained from show that this osmotic pressure equals the disjoining pressure. 41 Here we do not exploit the relationship between disjoining and osmotic pressure but invoke the equivalence of different ensembles in the thermodynamic limit to apply the relationship, eqn (13), between the experimentally observed changes in the bilayer area and thickness in order to evaluate the interbilayer repulsion inducing these structural changes.…”

mentioning

confidence: 99%

Interbilayer repulsion forces between tension-free lipid bilayers from simulation

et al. 2013

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Here we report studies on biologically important intermembrane repulsion forces using molecular dynamics (MD) simulations and experimental (osmotic stress) investigations of repulsion forces between 1-palmitoyl-2-oleyl-sn-glycero-3-phosphocholine bilayers. We show that the repulsion between tensionfree membranes can be determined from MD simulations by either (i) simulating membrane stacks under different hydration conditions (unrestrained setup) and monitoring the change in the area per lipid upon dehydration or (ii) simulating two single punctured membranes immersed in a water reservoir and controlling the center-of-mass distance between the bilayers using an external potential (umbrella sampling setup). Despite the coarse-grained nature of the (MARTINI) model employed, the disjoining pressure profiles obtained from the simulations are in good agreement with our experiments.Remarkably, the two setups behave very differently in terms of membrane structure, as explained by considerations using elasticity theory, and the balance of interactions. In the unrestrained setup, dehydration decreases the area per lipid and lipid entropy. Dehydration in the umbrella sampling setup, in contrast, leads to an increase in area per lipid and lipid entropy. Hence, in the latter case, entropic effects from protrusion and zippering forces appear to be overcompensated by the entropy gain due to the disorder emerging from the expansion of the bilayers. The balance of interactions involves near cancellation of large opposing terms, for which also intramembrane and water-water interactions are important, and which appears to be largely a consequence, rather than the cause, of the intermembrane repulsion. Hence, care must be taken when drawing conclusions on the origin of intermembrane repulsion from thermodynamic analyses.

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mentioning

confidence: 99%

Interbilayer repulsion forces between tension-free lipid bilayers from simulation

et al. 2013

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“…This could explain the larger d-spacing values observed in the current analysis. The reconstruction of the bilayer profile indicates that the water layer is $45 Å thick, a value larger than that commonly expected for stacks of zwitterionic membranes (Aeffner, 2012) but perfectly explicable by assuming strong electrostatic repulsion. This picture is also compatible with the small decrease in the d a spacing upon dehydration.…”

Section: Discussionmentioning

confidence: 76%

“…Equilibrium between these forces leads to well defined bilayer-to-bilayer distances. The corresponding water-layer thickness between adjacent zwitterionic lipid bilayers is typically between 10 and 30 Å depending on the exact lipid composition and phase (Aeffner, 2012). The presence of water molecules between two bilayers causes the so-called hydration repulsion effect (Israelachvili & Wennerstroem, 1992).…”

Section: Discussionmentioning

confidence: 99%

Multi-lamellar organization of fully deuterated lipid extracts of yeast membranes

Gerelli

Ghellinck

Jouhet

et al. 2014

Acta Cryst D Biol Crystallogr

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Neutron scattering studies on mimetic biomembranes are currently limited by the low availability of deuterated unsaturated lipid species. In the present work, results from the first neutron diffraction experiments on fully deuterated lipid extracts from the yeast Pichia pastoris are presented. The structural features of these fully deuterated lipid stacks are compared with those of their hydrogenous analogues and with other similar synthetic systems. The influence of temperature and humidity on the samples has been investigated by means of small momentum-transfer neutron diffraction. All of the lipid extracts investigated self-assemble into multi-lamellar stacks having different structural periodicities; the stacking distances are affected by temperature and humidity without altering the basic underlying arrangement. At high relative humidity the deuterated and hydrogenous samples are similar in their multi-lamellar arrangement, being characterized by two main periodicities of ∼75 and ∼110 Å reflecting the presence of a large number of polar phospholipid molecules. Larger differences are found at lower relative humidity, where hydrogenous lipids are characterized by a larger single lamellar structure than that observed in the deuterated samples. In both cases the heterogeneity in composition is reflected in a wide structural complexity. The different behaviour upon dehydration can be related to compositional differences in the molecular composition of the two samples, which is attributed to metabolic effects related to the use of perdeuterated growth media.

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“…the swelling method [96], reference data for a broad range of lipid model systems is readily available [30,31]. Details on the Fourier synthesis approach as well as the application of the swelling method to lamellar and non-lamellar lipid phases are extensively reviewed in [53,52,97].…”

Section: Specular Scattering From Lipid Multilayersmentioning

confidence: 99%

“…In line with the argumentation in 2.3 and [52,53,98] it is additionally assumed that the integral over the continuous form factor squared F (q z , t)…”

Section: Excitation Of Lipid Multilayers On Silicon Substrates By Nanmentioning

confidence: 99%

Non-equilibrium dynamics of lipid bilayers

Reusch¹

2013

Göttingen Series in X-Ray Physics

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Stalk structures in lipid bilayer fusion studied by x-ray diffraction

Cited by 9 publications

References 128 publications

Interbilayer repulsion forces between tension-free lipid bilayers from simulation

Interbilayer repulsion forces between tension-free lipid bilayers from simulation

Multi-lamellar organization of fully deuterated lipid extracts of yeast membranes

Non-equilibrium dynamics of lipid bilayers

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