Block Liposomes from Curvature-Stabilizing Lipids: Connected Nanotubes, -rods, or -spheres

Zidovska, Alexandra; Ewert, Kai K.; Quispe, Joel; Carragher, Bridget; Potter, Clinton S.; Safinya, Cyrus R.

doi:10.1021/la8022375

Cited by 29 publications

(85 citation statements)

References 32 publications

(64 reference statements)

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“…49 Furthermore, small vesicles with a preferred radius have been seen in experiments on mixtures of sphere-and lamella-forming amphiphiles. 7,54 Their existence has also been predicted in recent lattice SCFT calculations by Li et al 55 Our current work considers a different region of parameter space to these lattice-based calculations, which focus on weakly mismatched amphiphiles and (usually) higher lamella-former concentrations. In consequence, the mechanism by which the preferred vesicle radius is selected appears to be rather different in the two studies.…”

Section: Effect Of Lamella-former Concentrationmentioning

confidence: 63%

“…Furthermore, several of the structures shown here show the segregation of amphiphiles according to curvature. 7,20 Specifically, in many cases, the sphereforming amphiphiles move to the positively-curved surface of the aggregate. Effectively onedimensional aggregates such as those considered here are among the simplest possible systems in which this phenomenon could take place.…”

Section: Discussionmentioning

confidence: 99%

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Simple and Complex Micelles in Amphiphilic Mixtures: A Coarse-Grained Mean-Field Study

Greenall¹,

Gompper

2011

Macromolecules

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Binary mixtures of amphiphiles in solution can self-assemble into a wide range of structures when the two species individually form aggregates of different curvatures. In this paper, we focus on small, spherically-symmetric aggregates in a solution of sphere-forming amphiphile mixed with a smaller amount of lamella-forming amphiphile. Using a coarsegrained mean-field model (self-consistent field theory, or SCFT), we scan the parameter space of this system and find a range of morphologies as the interaction strength, architecture and mixing ratio of the amphiphiles are varied. When the two species are quite similar in architecture, or when only a small amount of lamella-former is added, we find simple spherical micelles with cores formed from a mixture of the hydrophobic blocks of the two amphiphiles.For more strongly mismatched amphiphiles and higher lamella-former concentrations, we instead find small vesicles and more complex micelles. In these latter structures, the lamella- Simple and complex micelles in . . . be large, and the implications of this for the solubilization of hydrophobic chemicals are considered. The mechanisms behind the formation of the above structures are discussed, with a particular emphasis on the sorting of amphiphiles according to their preferred curvature.

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Section: Effect Of Lamella-former Concentrationmentioning

confidence: 63%

Section: Discussionmentioning

confidence: 99%

Simple and Complex Micelles in Amphiphilic Mixtures: A Coarse-Grained Mean-Field Study

Greenall¹,

Gompper

2011

Macromolecules

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“…Interestingly, several studies suggest that truncated BH3 interactingdomain death agonist (tBid) and/or Bcl-2-associated X protein (BAX) may cause outer mitochondrial membrane lipidic pores related to curvature (18)(19)(20)(21). Other species that cause membrane structural changes in analogous ways include modified lipids and cationic nanoparticles (44,45).…”

Section: Discussionmentioning

confidence: 99%

Cytochrome c causes pore formation in cardiolipin-containing membranes

Bergstrom

Beales

Yang

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

123

135

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The release of cytochrome c from mitochondria is a key signaling mechanism in apoptosis. Although extramitochondrial proteins are thought to initiate this release, the exact mechanisms remain unclear. Cytochrome c (cyt c) binds to and penetrates lipid structures containing the inner mitochondrial membrane lipid cardiolipin (CL), leading to protein conformational changes and increased peroxidase activity. We describe here a direct visualization of a fluorescent cyt c crossing synthetic, CL-containing membranes in the absence of other proteins. We observed strong binding of cyt c to CL in phospholipid vesicles and bursts of cyt c leakage across the membrane. Passive fluorescent markers such as carboxyfluorescein and a 10-kDa dextran polymer crossed the membrane simultaneously with cyt c, although larger dextrans did not. The data show that these bursts result from the opening of lipid pores formed by the cyt c-CL conjugate. Pore formation and cyt c leakage were significantly reduced in the presence of ATP. We suggest a model, consistent with these findings, in which the formation of toroidal lipid pores is driven by initial cyt c-induced negative spontaneous membrane curvature and subsequent protein unfolding interactions. Our results suggest that the CL-cyt c interaction may be sufficient to allow cyt c permeation of mitochondrial membranes and that cyt c may contribute to its own escape from mitochondria during apoptosis.

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“…Nonetheless, cell-free experiments conducted under suitable buffer and ionic strength conditions can result in functionally significant assemblies at or near equilibrium or in kinetically trapped states, with structures similar to those occurring in vivo as determined by EM. Well-documented examples include lipids assembled into bilayer membranes exhibiting a range of shapes (40)(41)(42)(43)(44)(45), bundles of filamentous actin (7,11,(46)(47)(48)(49)(50)(51)(52)(53)(54)(55)(56) and MTs (57)(58)(59)(60)(61), and networks of NFs, all of which may show similar cell-free and in vivo structures. For example, for NF hydrogels described in this review (33)(34)(35)(36)62), variations in ionic strength, which tune the electrostatic forces in cell-free systems, qualitatively mimic the changes in intermolecular interactions in vivo, and are mediated by out-of-equilibrium enzyme-directed phosphorylation/ dephosphorylation of the NF sidearms at constant ionic strength.…”

Section: Introductionmentioning

confidence: 99%

Assembly of Biological Nanostructures: Isotropic and Liquid Crystalline Phases of Neurofilament Hydrogels

Safinya

Deek

Beck

et al. 2015

Annu. Rev. Condens. Matter Phys.

Self Cite

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Neurofilaments are the building blocks of the major cytoskeletal network found in the axons of vertebrate neurons. The filaments consist of three distinct molecularweight subunits-neurofilament-low, neurofilament-medium, and neurofilamenthigh-which coassemble into 10-nm flexible rods with protruding intrinsically disordered C-terminal sidearms that mediate interfilament interactions and hydrogel formation. Molecular neuroscience research includes areas focused on elucidating the functions of each subunit in network formation, during which disruptions are a hallmark of motor-neuron diseases. Here, modern concepts and methods from soft condensed matter physics are combined to address the role of subunits as it relates to interfilament forces and phase behavior in neurofilament networks. Significantly, the phase behavior studies reveal that although neurofilamentmedium subunits promote nematic liquid crystal hydrogel phase stability with parallel filament orientation, neurofilament-high subunits stabilize the hydrogel in the nematic phase close to the isotropic gel phase with random, crossed-filament orientation. This indicates a regulatory role for neurofilament-high subunits in filament orientational plasticity required for organelle (e.g., membrane-bound vesicle or mitochondrion) transport along microtubules embedded in neurofilament hydrogels. Future studies-for example, on neurofilament subunits mixed with tubulin and microtubule-associated proteins-should lead to a deeper understanding of forces and heterogeneous structures in neuronal cytoskeletons. 6.1Review in Advance first posted online on January 2, 2015. (Changes may still occur before final publication online and in print.)Changes may still occur before final publication online and in print Annu. Rev. Condens. Matter Phys. 2015.6. Downloaded from www.annualreviews.org Access provided by Selcuk University on 01/05/15. For personal use only.

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Block Liposomes from Curvature-Stabilizing Lipids: Connected Nanotubes, -rods, or -spheres

Cited by 29 publications

References 32 publications

Simple and Complex Micelles in Amphiphilic Mixtures: A Coarse-Grained Mean-Field Study

Simple and Complex Micelles in Amphiphilic Mixtures: A Coarse-Grained Mean-Field Study

Cytochrome c causes pore formation in cardiolipin-containing membranes

Assembly of Biological Nanostructures: Isotropic and Liquid Crystalline Phases of Neurofilament Hydrogels

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