scholarly journals Induction of Highly Curved Structures in Relation to Membrane Permeabilization and Budding by the Triterpenoid Saponins, α- and δ-Hederin

2013 ◽  
Vol 288 (20) ◽  
pp. 14000-14017 ◽  
Author(s):  
Joseph Lorent ◽  
Cécile S. Le Duff ◽  
Joelle Quetin-Leclercq ◽  
Marie-Paule Mingeot-Leclercq
Keyword(s):  
Lipid Membranes ◽  
Pore Formation ◽  
Lateral Diffusion ◽  
Molecular Shape ◽  
Membrane Curvature ◽  
Membrane Permeabilization ◽  
Spontaneous Curvature ◽  
Unilamellar Vesicles ◽  
Generalized Polarization ◽  
Triterpenoid Saponins

The interactions of triterpenoid monodesmosidic saponins, α-hederin and δ-hederin, with lipid membranes are involved in their permeabilizing effect. Unfortunately, the interactions of these saponins with lipid membranes are largely unknown, as are the roles of cholesterol or the branched sugar moieties (two for α-hederin and one for δ-hederin) on the aglycone backbone, hederagenin. The differences in sugar moieties are responsible for differences in the molecular shape of the saponins and the effects on membrane curvature that should be the most positive for α-hederin in a transbilayer direction. In large unilamellar vesicles and monocyte cells, we showed that membrane permeabilization was dependent on the presence of membrane cholesterol and saponin sugar chains, being largest for α-hederin and smallest for hederagenin. In the presence of cholesterol, α-hederin induced the formation of nonbilayer phases with a higher rate of Brownian tumbling or lateral diffusion. A reduction of Laurdan's generalized polarization in relation to change in order of the polar heads of phospholipids was observed. Using giant unilamellar vesicles, we visualized the formation of wrinkled borders, the decrease in liposome size, budding, and the formation of macroscopic pores. All these processes are highly dependent on the sugars linked to the aglycone, with α-hederin showing a greater ability to induce pore formation and δ-hederin being more efficient in inducing budding. Hederagenin induced intravesicular budding but no pore formation. Based on these results, a curvature-driven permeabilization mechanism dependent on the interaction between saponin and sterols and on the molecular shape of the saponin and its ability to induce local spontaneous curvature is proposed.

Single Vesicle Analysis Reveals Nanoscale Membrane Curvature Selective Pore Formation in Lipid Membranes by an Antiviral α-Helical Peptide

Nano Letters ◽  
2012 ◽  
Vol 12 (11) ◽  
pp. 5719-5725 ◽  
Author(s):  
Seyed R. Tabaei ◽  
Michael Rabe ◽  
Vladimir P. Zhdanov ◽  
Nam-Joon Cho ◽  
Fredrik Höök
Keyword(s):  
Lipid Membranes ◽  
Pore Formation ◽  
Membrane Curvature ◽  
Helical Peptide ◽  
Single Vesicle

scholarly journals Correlating biological activity to thermo-structural analysis of the interaction of CTX with synthetic models of macrophage membranes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Luciana de Araújo Pimenta ◽  
Evandro L. Duarte ◽  
Gabriel S. Vignoli Muniz ◽  
Kerly Fernanda Mesquita Pasqualoto ◽  
Marcos Roberto de Mattos Fontes ◽  
...  
Keyword(s):  
Lipid Membranes ◽  
Pore Formation ◽  
Biological Activities ◽  
Membrane Surface ◽  
Membrane Curvature ◽  
Structural Alterations ◽  
Opening And Closing ◽  
Crotalus Durissus ◽  
Synthetic Models ◽  
Access Pathway

AbstractThe important pharmacological actions of Crotoxin (CTX) on macrophages, the main toxin in the venom of Crotalus durissus terrificus, and its important participation in the control of different pathophysiological processes, have been demonstrated. The biological activities performed by macrophages are related to signaling mediated by receptors expressed on the membrane surface of these cells or opening and closing of ion channels, generation of membrane curvature and pore formation. In the present work, the interaction of the CTX complex with the cell membrane of macrophages is studied, both using biological cells and synthetic lipid membranes to monitor structural alterations induced by the protein. Here we show that CTX can penetrate THP-1 cells and induce pores only in anionic lipid model membranes, suggesting that a possible access pathway for CTX to the cell is via lipids with anionic polar heads. Considering that the selectivity of the lipid composition varies in different tissues and organs of the human body, the thermostructural studies presented here are extremely important to open new investigations on the biological activities of CTX in different biological systems.

scholarly journals Effect of Ursolic and Oleanolic Acids on Lipid Membranes: Studies on MRSA and Models of Membranes

Antibiotics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1381
Author(s):  
Sandrine Verstraeten ◽  
Lucy Catteau ◽  
Laila Boukricha ◽  
Joelle Quetin-Leclercq ◽  
Marie-Paule Mingeot-Leclercq
Keyword(s):  
Membrane Fluidity ◽  
Lipid Membranes ◽  
Chemical Space ◽  
Opportunistic Pathogen ◽  
Membrane Permeabilization ◽  
Generalized Polarization ◽  
Pentacyclic Triterpenes ◽  
Group Position ◽  
Dose Dependent

Staphylococcus aureus is an opportunistic pathogen and the major causative agent of life-threatening hospital- and community-acquired infections. A combination of antibiotics could be an opportunity to address the widespread emergence of antibiotic-resistant strains, including Methicillin-Resistant S. aureus (MRSA). We here investigated the potential synergy between ampicillin and plant-derived antibiotics (pentacyclic triterpenes, ursolic acid (UA) and oleanolic acid (OA)) towards MRSA (ATCC33591 and COL) and the mechanisms involved. We calculated the Fractional Inhibitory Concentration Index (FICI) and demonstrated synergy. We monitored fluorescence of Bodipy-TR-Cadaverin, propidium iodide and membrane potential-sensitive probe for determining the ability of UA and OA to bind to lipoteichoic acids (LTA), and to induce membrane permeabilization and depolarization, respectively. Both pentacyclic triterpenes were able to bind to LTA and to induce membrane permeabilization and depolarization in a dose-dependent fashion. These effects were not accompanied by significant changes in cellular concentration of pentacyclic triterpenes and/or ampicillin, suggesting an effect mediated through lipid membranes. We therefore focused on membranous effects induced by UA and OA, and we investigated on models of membranes, the role of specific lipids including phosphatidylglycerol and cardiolipin. The effect induced on membrane fluidity, permeability and ability to fuse were studied by determining changes in fluorescence anisotropy of DPH/generalized polarization of Laurdan, calcein release from liposomes, fluorescence dequenching of octadecyl-rhodamine B and liposome-size, respectively. Both UA and OA showed a dose-dependent effect with membrane rigidification, increase of membrane permeabilization and fusion. Except for the effect on membrane fluidity, the effect of UA was consistently higher compared with that obtained with OA, suggesting the role of methyl group position. All together the data demonstrated the potential role of compounds acting on lipid membranes for enhancing the activity of other antibiotics, like ampicillin and inducing synergy. Such combinations offer an opportunity to explore a larger antibiotic chemical space.

scholarly journals Cardiolipin-Containing Lipid Membranes Attract the Bacterial Cell Division Protein DivIVA

2021 ◽  
Vol 22 (15) ◽  
pp. 8350
Author(s):  
Naďa Labajová ◽  
Natalia Baranova ◽  
Miroslav Jurásek ◽  
Robert Vácha ◽  
Martin Loose ◽  
...  
Keyword(s):  
Cell Division ◽  
Lipid Bilayers ◽  
Bacterial Cell ◽  
Lipid Membranes ◽  
Model Organism ◽  
Active Role ◽  
Membrane Curvature ◽  
Bacterial Cell Division ◽  
Division Site ◽  
Clostridioides Difficile

DivIVA is a protein initially identified as a spatial regulator of cell division in the model organism Bacillus subtilis, but its homologues are present in many other Gram-positive bacteria, including Clostridia species. Besides its role as topological regulator of the Min system during bacterial cell division, DivIVA is involved in chromosome segregation during sporulation, genetic competence, and cell wall synthesis. DivIVA localizes to regions of high membrane curvature, such as the cell poles and cell division site, where it recruits distinct binding partners. Previously, it was suggested that negative curvature sensing is the main mechanism by which DivIVA binds to these specific regions. Here, we show that Clostridioides difficile DivIVA binds preferably to membranes containing negatively charged phospholipids, especially cardiolipin. Strikingly, we observed that upon binding, DivIVA modifies the lipid distribution and induces changes to lipid bilayers containing cardiolipin. Our observations indicate that DivIVA might play a more complex and so far unknown active role during the formation of the cell division septal membrane.

Membrane curvature and the control of GTP hydrolysis in Arf1 during COPI vesicle formation

2005 ◽  
Vol 33 (4) ◽  
pp. 619-622 ◽  
Author(s):  
B. Antonny ◽  
J. Bigay ◽  
J.-F. Casella ◽  
G. Drin ◽  
B. Mesmin ◽  
...  
Keyword(s):  
Lipid Membranes ◽  
Membrane Curvature ◽  
Gtp Hydrolysis ◽  
Membrane Fission ◽  
Transport Vesicles ◽  
Highly Sensitive ◽  
Copi Vesicle ◽  
Membrane Budding ◽  
Gtpase Cycle ◽  
Adp Ribosylation Factor

The GTP switch of the small G-protein Arf1 (ADP-ribosylation factor 1) on lipid membranes promotes the polymerization of the COPI (coat protein complex I) coat, which acts as a membrane deforming shell to form transport vesicles. Real-time measurements for coat assembly on liposomes gives insights into how the GTPase cycle of Arf1 is coupled in time with the polymerization of the COPI coat and the resulting membrane deformation. One key parameter seems to be the membrane curvature. Arf-GAP1 (where GAP stands for GTPase-activating protein), which promotes GTP hydrolysis in the Arf1–COPI complex is highly sensitive to lipid packing. Its activity on Arf1-GTP increases by two orders of magnitude as the diameter of the liposomes approaches that of authentic transport vesicles (60 nm). This suggests that during membrane budding, Arf1-GTP molecules are progressively eliminated from the coated area where the membrane curvature is positive, but are protected from Arf-GAP1 at the bud neck due to the negative curvature of this region. As a result, the coat should be stable as long as the bud remains attached and should disassemble as soon as membrane fission occurs.

Membrane re-modelling by BAR domain superfamily proteins via molecular and non-molecular factors

2018 ◽  
Vol 46 (2) ◽  
pp. 379-389 ◽  
Author(s):  
Tamako Nishimura ◽  
Nobuhiro Morone ◽  
Shiro Suetsugu
Keyword(s):  
Lipid Membranes ◽  
Intracellular Transport ◽  
Lipid Membrane ◽  
Membrane Curvature ◽  
Membrane Dynamics ◽  
Cytoskeletal Proteins ◽  
Cellular Functions ◽  
High Concentration ◽  
Bar Domain ◽  
Intracellular Organelles

Lipid membranes are structural components of cell surfaces and intracellular organelles. Alterations in lipid membrane shape are accompanied by numerous cellular functions, including endocytosis, intracellular transport, and cell migration. Proteins containing Bin–Amphiphysin–Rvs (BAR) domains (BAR proteins) are unique, because their structures correspond to the membrane curvature, that is, the shape of the lipid membrane. BAR proteins present at high concentration determine the shape of the membrane, because BAR domain oligomers function as scaffolds that mould the membrane. BAR proteins co-operate with various molecular and non-molecular factors. The molecular factors include cytoskeletal proteins such as the regulators of actin filaments and the membrane scission protein dynamin. Lipid composition, including saturated or unsaturated fatty acid tails of phospholipids, also affects the ability of BAR proteins to mould the membrane. Non-molecular factors include the external physical forces applied to the membrane, such as tension and friction. In this mini-review, we will discuss how the BAR proteins orchestrate membrane dynamics together with various molecular and non-molecular factors.

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