Dynamics and Size of Cross-Linking-Induced Lipid Nanodomains in Model Membranes

Štefl, Martin; Šachl, Radek; Humpolíčková, Jana; Cebecauer, Marek; Macháň, Radek; Kolářová, Marie; Johansson, Lennart B.‐Å.; Hof, Martin

doi:10.1016/j.bpj.2012.03.054

Cited by 57 publications

(59 citation statements)

References 38 publications

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“…[6][7][8][9][10][11][12][13] This toxin belongs to the AB 5 superfamily of toxins, which contains an active (A) unit and five identical binding (B) subunits. 7 The binding unit of the cholera toxin (CTB) binds specifically to monosialotetrahexosylganglioside (GM1) lipid via multivalent electrostatic attraction.…”

Section: Introductionmentioning

confidence: 99%

Nanodomain Formation of Ganglioside GM1 in Lipid Membrane: Effects of Cholera Toxin-Mediated Cross-Linking

et al. 2015

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Cross-linking of specific lipid components by proteins mediates transmembrane signaling and material transport. In this work, we conducted coarse-grained simulation to investigate the interactions of binding units of chorela toxin (CTB) with mixed ganglioside GM1 and dipalmitoylphosphatidylcholine (DPPC) lipid bilayer membrane. We determine that the binding of CTB pentamers cross-links GM1 molecules into protein-sized nanodomains that have distinct lipid order compared with the bulk. The toxin in the nanodomain partially penetrates into the membrane. The local disordering can also transmit across the membrane via lipid coupling. Comparison simulations on CTB binding to a membrane that is composed of various lipid components demonstrate that several factors are responsible for the nanodomain formation: (a) the negatively charged headgroup of a GM1 receptor is responsible for the multivalent binding; (b) the head groups being full of hydrogen-bonding donors and receptors stabilize the GM1 cluster itself and ensure the toxin binding with high affinity; and

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Section: Introductionmentioning

confidence: 99%

Nanodomain Formation of Ganglioside GM1 in Lipid Membrane: Effects of Cholera Toxin-Mediated Cross-Linking

et al. 2015

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“…in the case of SV40 and the AB5 toxins [11], [12], [13], [14] such as Cholera toxin B (CtxB) [15], [16], [17], [18]. The Alzheimer's disease-causing Aβ peptide, like these toxins, may cluster at the membrane, seeded by gangliosides, into oligomers or aggregates of anywhere from a few molecules to larger protofibrils, or large pore-forming annuli [19], [20], [21], [22], [23], [24], [25], [26], [27].…”

Section: Introductionmentioning

confidence: 99%

Weak Glycolipid Binding of a Microdomain-Tracer Peptide Correlates with Aggregation and Slow Diffusion on Cell Membranes

et al. 2012

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Organized assembly or aggregation of sphingolipid-binding ligands, such as certain toxins and pathogens, has been suggested to increase binding affinity of the ligand to the cell membrane and cause membrane reorganization or distortion. Here we show that the diffusion behavior of the fluorescently tagged sphingolipid-interacting peptide probe SBD (Sphingolipid Binding Domain) is altered by modifications in the construction of the peptide sequence that both result in a reduction in binding to ganglioside-containing supported lipid membranes, and at the same time increase aggregation on the cell plasma membrane, but that do not change relative amounts of secondary structural features. We tested the effects of modifying the overall charge and construction of the SBD probe on its binding and diffusion behavior, by Surface Plasmon Resonance (SPR; Biacore) analysis on lipid surfaces, and by Fluorescence Correlation Spectroscopy (FCS) on live cells, respectively. SBD binds preferentially to membranes containing the highly sialylated gangliosides GT1b and GD1a. However, simple charge interactions of the peptide with the negative ganglioside do not appear to be a critical determinant of binding. Rather, an aggregation-suppressing amino acid composition and linker between the fluorophore and the peptide are required for optimum binding of the SBD to ganglioside-containing supported lipid bilayer surfaces, as well as for interaction with the membrane. Interestingly, the strength of interactions with ganglioside-containing artificial membranes is mirrored in the diffusion behavior by FCS on cell membranes, with stronger binders displaying similar characteristic diffusion profiles. Our findings indicate that for aggregation-prone peptides, aggregation occurs upon contact with the cell membrane, and rather than giving a stronger interaction with the membrane, aggregation is accompanied by weaker binding and complex diffusion profiles indicative of heterogeneous diffusion behavior in the probe population.

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“…Our understanding of the properties of CTxB–GM 1 complexes should also continue to be greatly increased by in vitro approaches. These include elegant biophysical approaches being used to study CTxB’s curvature sensing and generating abilities [26,27,32,33], follow the early stages of the formation of CTxB-enriched domains [37] and uncover the impact of CTxB binding on underlying membrane structure [38]. The development of new tools such as fluorescent glycolipid analogues and mutants toxins [20,25,27] are also now making it possible to directly probe the contributions of both cholera toxin and its receptor to the assembly, dynamics and function of these domains.…”

Section: Discussionmentioning

confidence: 99%

Functions of cholera toxin B-subunit as a raft cross-linker

Day

Kenworthy

2015

Essays in Biochemistry

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Lipid rafts are putative complexes of lipids and proteins in cellular membranes that are proposed to function in trafficking and signalling events. CTxB (cholera toxin B-subunit) has emerged as one of the most studied examples of a raft-associated protein. Consisting of the membrane-binding domain of cholera toxin, CTxB binds up to five copies of its lipid receptor on the plasma membrane of the host cell. This multivalency of binding gives the toxin the ability to reorganize underlying membrane structure by cross-linking otherwise small and transient lipid rafts. CTxB thus serves as a useful model for understanding the properties and functions of protein-stabilized domains. In the present chapter, we summarize current evidence that CTxB associates with and cross-links lipid rafts, discuss how CTxB binding modulates the architecture and dynamics of membrane domains, and describe the functional consequences of this cross-linking behaviour on toxin uptake into cells via endocytosis.

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Dynamics and Size of Cross-Linking-Induced Lipid Nanodomains in Model Membranes

Cited by 57 publications

References 38 publications

Nanodomain Formation of Ganglioside GM1 in Lipid Membrane: Effects of Cholera Toxin-Mediated Cross-Linking

Nanodomain Formation of Ganglioside GM1 in Lipid Membrane: Effects of Cholera Toxin-Mediated Cross-Linking

Weak Glycolipid Binding of a Microdomain-Tracer Peptide Correlates with Aggregation and Slow Diffusion on Cell Membranes

Functions of cholera toxin B-subunit as a raft cross-linker

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