The glycolipid GM1 reshapes asymmetric biomembranes and giant vesicles by curvature generation

Dasgupta, Ranjan; Miettinen, Markus S.; Fricke, Nico; Lipowsky, Reinhard; Dimova, Rumiana

doi:10.1073/pnas.1722320115

Cited by 103 publications

(112 citation statements)

References 57 publications

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“…6. This in turn leads to the generation of highly curved protrusions (nanotubes and buds) and an increase in the spontaneous tension (69,70). As a result, the projected area of the vesicle decreases.…”

Section: Discussionmentioning

confidence: 99%

“…3 E; Video S4) have these diameters and seem to become thinner and with diameters not optically resolvable as fusion proceeds further. The exact change in the membrane spontaneous curvature can be assessed with tube-pulling experiments (70) or micropipette aspiration (75) and remains to be confirmed. Presumably, lipid flip-flop over time would allow for relaxing the spontaneous curvature acquired from fusion.…”

Section: Discussionmentioning

confidence: 99%

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Highly Efficient Protein-free Membrane Fusion: A Giant Vesicle Study

Lira

Robinson

Dimova

et al. 2019

Biophysical Journal

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118

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Membrane fusion is a ubiquitous process in biology and is a prerequisite for many intracellular delivery protocols relying on the use of liposomes as drug carriers. Here, we investigate in detail the process of membrane fusion and the role of opposite charges in a protein-free lipid system based on cationic liposomes (LUVs, large unilamellar vesicles) and anionic giant unilamellar vesicles (GUVs) composed of different palmitoyloleoylphosphatidylcholine (POPC)/palmitoyloleoylphosphatidylglycerol (POPG) molar ratios. By using a set of optical-microscopy-and microfluidics-based methods, we show that liposomes strongly dock to GUVs of pure POPC or low POPG fraction (up to 10 mol%) in a process mainly associated with hemifusion and membrane tension increase, commonly leading to GUV rupture. On the other hand, docked LUVs quickly and very efficiently fuse with negative GUVs of POPG fractions at or above 20 mol%, resulting in dramatic GUV area increase in a charge-dependent manner; the vesicle area increase is deduced from GUV electrodeformation. Importantly, both hemifusion and full fusion are leakage-free. Fusion efficiency is quantified by the lipid transfer from liposomes to GUVs using fluorescence resonance energy transfer (FRET), which leads to consistent results when compared to fluorescence-lifetime-based FRET. We develop an approach to deduce the final composition of single GUVs after fusion based on the FRET efficiency. The results suggest that fusion is driven by membrane charge and appears to proceed up to charge neutralization of the acceptor GUV.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Highly Efficient Protein-free Membrane Fusion: A Giant Vesicle Study

Lira

Robinson

Dimova

et al. 2019

Biophysical Journal

Self Cite

118

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“…The OMVs sequestered gangliosides within the host plasma membrane to produce large ganglioside clusters, which have been found to lower local bending parameters and dramatically enhance preferences for spontaneous curvature and bilayer reshaping. [39][40][57][58] Plasma membrane heterogeneity also affected bilayer bending: constituent lipids were able to reorganize themselves to reduce line tension energies e.g. PIP 2 lipids were preferentially partitioned to the inner plasma membrane leaflet when it was made round through interactions with the smooth OMV.…”

Section: Resultsmentioning

confidence: 99%

“…Given that ganglioside head groups support strong cohesive interactions with invasive toxins, and tend to facilitate membrane reshaping due to their high intrinsic positive curvature, we next explored the interaction of OMVs with more complex models of host membranes. [36][37][38][39][40][41] Both OMVs were simulated with a pre-equilibrated, [32][33][34][35][36][37][38][39][40][41][42][43][44][45] multicomponent plasma membrane model composed of POPC (25%), POPE (25%) 1palmitoyl-2-oleoyl phosphatidyl serine, or POPS (7.5%), GM3 ganglioside (5%), sphingomyelin (7.5%), cholesterol (25%) and phosphatidylinositol 4,5-biphosphate, or PIP 2 (5%). Table 3 and Table 4 summarize the findings from these simulations, which are described in detail below.…”

Section: Omvs Interacting With Model Plasma Membranesmentioning

confidence: 99%

To infect or not to infect: molecular determinants of bacterial outer membrane vesicle internalization by host membranes

Jefferies

Khalid

2019

Preprint

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Outer membrane vesicles (OMVs) are spherical liposomes that are secreted by almost all forms of Gram-negative bacteria. The nanospheres contribute to bacterial pathogenesis by trafficking molecular cargo from bacterial membranes to target cells at the host-pathogen interface. We have simulated the interaction of OMVs with host cell membranes to understand why OMV uptake depends on the length of constituent lipopolysaccharide macromolecules. Using coarse-grained molecular dynamics simulations, we show that lipopolysaccharide lipid length affects OMV shape at the host-pathogen interface: OMVs with long (smooth-type) lipopolysaccharide lipids retain their spherical shape when they interact with host cell membranes, whereasOMVs with shorter (rough-type) lipopolysaccharide lipids distort and spread over the host membrane surface. In addition, we show that OMVs preferentially coordinate domain-favoring ganglioside lipids within host membranes to enhance curvature and affect the local lipid composition. We predict that these differences in shape preservation affect OMV internalization on long timescales: spherical nanoparticles tend to be completely enveloped by host membranes, whereas low sphericity nanoparticles tend to remain on the surface of cells.

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“…The clustering of lipids by AB5 toxins and SV40 virus is thought to induce compression of the lipids as a means of bending membranes (10,22,32) via a process linked to the geometry of receptor binding sites (9,33). However, much of this process warrants further characterization, including the role of the clustering and leaflet asymmetry in the generation of curvature (34). In this study, we investigated the factors that drive membrane bending by CTxB, a prototypical cargo for clathrin-independent endocytosis, using super-resolution polarized localization microscopy.…”

Section: Discussionmentioning

confidence: 99%

Structured clustering of the glycosphingolipid GM1 is required for membrane curvature induced by cholera toxin

Kabbani

Raghunathan

Lencer

et al. 2020

Preprint

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AB5 bacterial toxins and polyomaviruses induce membrane curvature as a mechanism to facilitate their entry into host cells. How membrane bending is accomplished is not yet fully understood but has been linked to the simultaneous binding of the pentameric B-subunit to multiple copies of their glycosphingolipid receptors. Here, we probe the toxin membrane binding and internalization mechanisms by using a combination of super-resolution and polarized localization microscopy. We show that cholera toxin subunit B (CTxB) can induce membrane curvature only when bound to multiple copies of its glycosphingolipid receptor, GM1, and the ceramide structure of GM1 is likely not a determinant of this activity as assessed in model membranes. A mutant CTxB capable of binding only a single GM1 fails to generate curvature either in model membranes or in cells and clustering the mutant CTxB-single-GM1 complexes by antibody cross-linking does not rescue the membrane curvature phenotype. We conclude that both the multiplicity and specific geometry of GM1 binding sites are necessary for the induction of membrane curvature. We expect this to be a general rule of membrane behavior for all AB5 toxins and polyomaviruses that bind glycosphingolipids to invade host cells.SIGNIFICANCE STATEMENTMembrane binding toxins demonstrate both a public health challenge and a bioengineering opportunity due to their efficient internalization into cells. These toxins multivalently bind to naturally occurring lipid receptors at the plasma membrane and initiate endocytosis. This manuscript reports the importance of structured lipid-receptor clustering for the induction of membrane bending. We also observed that the magnitude of membrane curvature was correlated to the stoichiometry of toxin-bound receptors. By identifying how these bacterial proteins initiate membrane curvature, these findings provide mechanistic insights into the early steps of pathogenic endocytosis.

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The glycolipid GM1 reshapes asymmetric biomembranes and giant vesicles by curvature generation

Cited by 103 publications

References 57 publications

Highly Efficient Protein-free Membrane Fusion: A Giant Vesicle Study

Highly Efficient Protein-free Membrane Fusion: A Giant Vesicle Study

To infect or not to infect: molecular determinants of bacterial outer membrane vesicle internalization by host membranes

Structured clustering of the glycosphingolipid GM1 is required for membrane curvature induced by cholera toxin

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