An investigation into the critical tension of electroporation in anionic lipid vesicles

Anionic lipid membrane electrostatic potential and solution pH can influence cationic peptide adsorption to these bilayers, especially those containing simultaneously acid and basic residues. Here, we investigate the effects of the pH solution on MP1 (IDWKKLLDAAKQIL-NH2) adsorption to anionic (7POPC:3POPG) lipid vesicles in comparison to its analog H-MP1, with histidines substituting lysines. We used the association of adsorption isotherms and constant pH molecular dynamic simulations (CpHMD) to explore the effects of membrane potential and pH on peptides’ adsorption on this lipid membrane. We analyzed the fluorescence and zeta potential adsorption isotherms using the Gouy–Chapman theory. In CpHMD simulations for the peptides in solution and adsorbed on the lipid bilayer, we used the conformations obtained by conventional MD simulations at a μs timescale. Non-equilibrium Monte Carlo simulations provided the protonation states of acidic and basic residues. CpHMD showed average pKa shifts of two to three units, resulting in a higher net charge for the analog than for MP1, strongly modulating the peptide adsorption. The fractions of the protonation of acidic and basic residues and the peptides’ net charges obtained from the analysis of the adsorption isotherms were in reasonable agreement with those from CpHMD. MP1 adsorption was almost insensitive to solution pH. H-MP1 was much more sensitive to partitioning, at acidic pH, with an affinity ten times higher than in neutral ones.

Download Full-text

Influence of Lipid Composition on Pediocin PA-1 Binding to Phospholipid Vesicles

Applied and Environmental Microbiology ◽

10.1128/aem.64.9.3530-3532.1998 ◽

1998 ◽

Vol 64 (9) ◽

pp. 3530-3532 ◽

Cited By ~ 29

Author(s):

Yuhuan Chen ◽

Richard D. Ludescher ◽

Thomas J. Montville

Keyword(s):

Fatty Acid ◽

Electrostatic Interaction ◽

Lipid Content ◽

Interaction Model ◽

Lipid Vesicles ◽

Phospholipid Vesicles ◽

Binding Parameters ◽

Lipid Concentration ◽

Anionic Lipid ◽

Lipid Interactions

ABSTRACT Pediocin PA-1 bound to anionic lipid vesicles with saturated or unsaturated fatty acid chains in a lipid concentration-dependent fashion. Little change in binding parameters was observed for zwitterionic lipid vesicles. Decreasing the anionic lipid content of the vesicles gave a higher relative dissociation constant for the peptide-lipid interactions and further supports the electrostatic interaction model of binding.

Download Full-text

Binding of Daptomycin to Anionic Lipid Vesicles Is Reduced in the Presence of Lysyl-Phosphatidylglycerol

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00744-16 ◽

2016 ◽

Vol 60 (8) ◽

pp. 5051-5053 ◽

Cited By ~ 15

Author(s):

Tala O. Khatib ◽

Heather Stevenson ◽

Michael R. Yeaman ◽

Arnold S. Bayer ◽

Antje Pokorny

Keyword(s):

Staphylococcus Aureus ◽

Surface Charge ◽

Cytoplasmic Membrane ◽

Cationic Lipid ◽

Lipid Vesicles ◽

Cationic Peptides ◽

Surface Binding ◽

Anionic Lipid ◽

Content Type

ABSTRACTThe cytoplasmic membrane ofStaphylococcus aureuscontains ∼20 mol% of the net cationic lipid lysyl-phosphatidylglycerol (LPG). Elevated fractions of LPG are associated with increased resistance to cationic antibiotics, including the lipopeptide daptomycin (DAP). Although the surface charge of the bacterial cytoplasmic membrane is altered by LPG, surface binding of DAP was found to be only moderately affected in anionic vesicles containing 20 mol% LPG. These results suggest that charge repulsion cannot fully explain LPG-mediated resistance to cationic peptides.

Download Full-text

Electrochemical and Spectroscopic Study on the Interaction of Cytochrome c with Anionic Lipid Vesicles

Chinese Journal of Chemistry ◽

10.1002/cjoc.20030210514 ◽

2010 ◽

Vol 21 (5) ◽

pp. 544-549 ◽

Cited By ~ 1

Author(s):

Jing Wei-Guo ◽

Liu Chang-Wei ◽

Tang Ji-Lin ◽

Wu Zheng-Yan ◽

Dong Shao-Jun ◽

...

Keyword(s):

Cytochrome C ◽

Spectroscopic Study ◽

Lipid Vesicles ◽

Anionic Lipid

Download Full-text

The structure of membranes and membrane proteins embedded in amorphous ice

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100122563 ◽

1992 ◽

Vol 50 (1) ◽

pp. 432-433

Author(s):

Uwe Lücken ◽

Joachim Jäger

Keyword(s):

Phase Transition ◽

Transition Temperature ◽

Membrane Proteins ◽

Phase Transition Temperature ◽

Lipid Vesicles ◽

Freezing Stress ◽

Amorphous Ice ◽

Different Temperatures ◽

Band Pass ◽

Lipid Polymorphism

TEM imaging of frozen-hydrated lipid vesicles has been done by several groups Thermotrophic and lyotrophic polymorphism has been reported. By using image processing, computer simulation and tilt experiments, we tried to learn about the influence of freezing-stress and defocus artifacts on the lipid polymorphism and fine structure of the bilayer profile. We show integrated membrane proteins do modulate the bilayer structure and the morphology of the vesicles.Phase transitions of DMPC vesicles were visualized after freezing under equilibrium conditions at different temperatures in a controlled-environment vitrification system. Below the main phase transition temperature of 24°C (Fig. 1), vesicles show a facetted appearance due to the quasicrystalline areas. A gradual increase in temperature leads to melting processes with different morphology in the bilayer profile. Far above the phase transition temperature the bilayer profile is still present. In the band-pass-filtered images (Fig. 2) no significant change in the width of the bilayer profile is visible.

Download Full-text

Anticoagulant Activity of β2-Glycoprotein I Is Potentiated by a Distinct Subgroup of Anticardiolipin Antibodies

Thrombosis and Haemostasis ◽

10.1055/s-0038-1656368 ◽

1992 ◽

Vol 68 (03) ◽

pp. 297-300 ◽

Cited By ~ 130

Author(s):

Monica Galli ◽

Paul Comfurius ◽

Tiziano Barbui ◽

Robert F A Zwaal ◽

Edouard M Bevers

Keyword(s):

Human Plasma ◽

Anticoagulant Activity ◽

Factor Xa ◽

Type A ◽

Lipid Vesicles ◽

Dependent Manner ◽

Type B ◽

Distinct Subgroup ◽

Glycoprotein I ◽

Thrombin Formation

SummaryPlasmas of 16 patients positive for both IgG anticardiolipin (aCL) antibodies and lupus anticoagulant (LA) antibodies were subjected to adsorption with liposomes containing cardiolipin. In 5 of these plasmas both the anticardiolipin and the anticoagulant activities were co-sedimented with the liposomes in a dose-dependent manner, whereas in the remaining cases only the anticardiolipin activity could be removed by the liposomes, leaving the anticoagulant activity (LA) in the supernatant plasma. aCL antibodies purified from the first 5 plasmas were defined as aCL-type A, while the term aCL-type B was used for antibodies in the other 11 plasmas, from which 2 were selected for this study.Prolongation of the dRVVT was produced by affinity-purified aCL-type A antibodies in plasma of human as well as animal (bovine, rat and goat) origin. aCL-type B antibodies were found to be devoid of anticoagulant activity, while the corresponding supernatants containing LA IgG produced prolongation of the dRVVT only in human plasma.These anticoagulant activities of aCL-type A and of LA IgG's were subsequently evaluated in human plasma depleted of β2-glycoprotein I (β2-GPI), a protein which was previously shown to be essential in the binding of aCL antibodies to anionic phospholipids. Prolongation of the dRVVT by aCL-type A antibodies was abolished using β2-GPI deficient plasma, but could be restored upon addition of β2-GPI. In contrast, LA IgG caused prolongation of the dRVVT irrespective of the presence or absence of β2-GPI.Since β2-GPI binds to negatively-charged phospholipids and impedes the conversion of prothrombin by the factor Xa/Va enzyme complex (Nimpf et al., Biochim Biophys Acta 1986; 884: 142–9), comparison was made of the effect of aCL-type A and aCL-type B antibodies on the rate of thrombin formation in the presence and absence of β2-GPI. This was measured in a system containing highly purified coagulation factors Xa, Va and prothrombin and lipid vesicles composed of 20 mole% phosphatidylserine and 80 mole% phosphatidylcholine. No inhibition on the rate of thrombin formation was observed with both types of aCL antibodies when either β2-GPI or the lipid vesicles were omitted. Addition of β2-GPI to the prothrombinase assay in the presence of lipid vesicles causes a time-dependent inhibition which was not affected by the presence of aCL-type B or non-specific IgG. In contrast, the presence of aCL-type A antibodies dramatically increased the anticoagulant effect of β2-GPI. These data indicate that the anticoagulant activity of aCL-type A antibodies in plasma is mediated by β2-GPI.

Download Full-text