Double-bilayer: a new phase formed by lysophospholipids and the corresponding fatty acid

Funari, Sérgio S.; Rapp, Gert; Richter, Frank M.

doi:10.1590/s0100-40422009000400015

Cited by 9 publications

(10 citation statements)

References 15 publications

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“…A double bilayer lamellar phase (model A) was also detected in a mixture of lysophospholipids and fatty acid. 54 Its structure was confirmed by simulations of the X-ray scattering pattern. In our system, the lipid mixture consists of POPE with gel to liquid-crystalline phase transition temperature Tm ~ 24.7 °C, and POPG with Tm ~ -5.3 °C.…”

Section: Small-angle X-ray Diffractionmentioning

confidence: 73%

Unravelling a Mechanism of Action for a Cecropin A-Melittin Hybrid Antimicrobial Peptide: The Induced Formation of Multilamellar Lipid Stacks

et al. 2018

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An understanding of the mechanism of action of antimicrobial peptides is fundamental to the development of new and more active antibiotics. In the present work, we use a wide range of techniques (SANS, SAXD, DSC, ITC, CD, and confocal and electron microscopy) in order to fully characterize the interaction of a cecropin A-melittin hybrid antimicrobial peptide, CA(1-7)M(2-9), of known antimicrobial activity, with a bacterial model membrane of POPE/POPG in an effort to unravel its mechanism of action. We found that CA(1-7)M(2-9) disrupts the vesicles, inducing membrane condensation and forming an onionlike structure of multilamellar stacks, held together by the intercalated peptides. SANS and SAXD revealed changes induced by the peptide in the lipid bilayer thickness and the bilayer stiffening in a tightly packed liquid-crystalline lamellar phase. The analysis of the observed abrupt changes in the repeat distance upon the phase transition to the gel state suggests the formation of an L phase. To the extent of our knowledge, this is the first time that the L phase is identified as part of the mechanism of action of antimicrobial peptides. The energetics of interaction depends on temperature, and ITC results indicate that CA(1-7)M(2-9) interacts with the outer leaflet. This further supports the idea of a surface interaction that leads to membrane condensation and not to pore formation. As a result, we propose that this peptide exerts its antimicrobial action against bacteria through extensive membrane disruption that leads to cell death.

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Section: Small-angle X-ray Diffractionmentioning

confidence: 73%

Unravelling a Mechanism of Action for a Cecropin A-Melittin Hybrid Antimicrobial Peptide: The Induced Formation of Multilamellar Lipid Stacks

et al. 2018

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“…

Lipid bilayers display a wide range of morphologies (di Vitta et al, 2013;Funari et al, 2009Funari et al, , 2011Silva et al, 2013; Valerio et al, 2012) and are simple models for the cell membrane. They not only provide a matrix for anchoring a variety of substances, for example, membrane proteins, glycolipids and so on, that play an essential role in the cell metabolism, but also define the cell limits keeping apart the inner and outer environments.

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confidence: 99%

Effect of urea and tmao on lipid bilayers

Valério

Bernstorff

Funari

2017

European Pharmaceutical Journal

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Lipid bilayers display a wide range of morphologies (di Vitta et al., 2013;Funari et al., 2009Funari et al., , 2011Silva et al., 2013; Valerio et al., 2012) and are simple models for the cell membrane. They not only provide a matrix for anchoring a variety of substances, for example, membrane proteins, glycolipids and so on, that play an essential role in the cell metabolism, but also define the cell limits keeping apart the inner and outer environments. Recently, we studied the structural effects of synthetic quinones on lipid model membranes in order to investigate their contribution to morphologies, possibly involved in transfer processes. Summarizing, we can say that the insertion of these additives lowers the temperature of the structural phase transitions, and in many cases, induce the formation of cubic phases at low temperatures, [1,2] which corresponds to an increase in the lipid matrix surface curvature. It is accepted that urea and (TMAO) have antagonistic effects on the fluidity of lipid membranes (Barton et al., 1998; Meersman & Walsh, 2011;Seibel et al., 2002). In red blood cells, urea slightly increases the gel-phase domains, but this effect is counteracted by TMAO. We intend to determine how these solutes affect the lipid membrane and determine their contribution to fluidity, or curvature, induced on them. OBJECTIVESWe intended to study the influence of natural osmolytes urea and TMAO on the fluidity and stability of lipid model membranes by determining the structure of the phases formed in the lipid dispersions. In this way, we expect to determine whether a dominant interaction of these solutes takes place on the lipids, or more indirectly, by affecting the properties of the aqueous region near the headgroup surface. Small and wide angle X-ray scattering (SAXS/WAXS) thermal scans enable us to determine the number of phases in each system, their transitions and respective reversibility. SAXS/WAXS identifies these structures and provide the dimensions of their lattices. Differential scanning calorimetry (DSC) provides the phase transition temperatures and the respective energy involved in such processes. MATERIALS AND METHODSThe samples were prepared by mixing desired volumes of stock solutions with well-defined concentrations of its components. The aqueous media at a temperature above the lipid main phase transition was directly added to the lipid. The samples were agitated slowly for two hours before they were filled into glass capillaries of 1.5 mm diameter and sealed. All chemicals were commercially available in high purity (POPE: Avanti lipids, TMAO and UREA : Sigma) and used without further purification. At the SAXS beamline of ELETTRA, an in-line microcalorimeter built by the group of Michel Ollivon (CNRS, Paris, France) (M. Ollivon et al., 2006) We study the effect of the osmolytes, Urea and trimethylamine-N-oxide (TMAO) on POPE (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine) lipid membranes using SAXS/WAXS and DSC. Their antagonist effect is observed with TMAO stabilizing and ...

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“…The cause can be either that there is a unit cell that does not contain one lipid bilayer but a double bilayer or, what is more plausible, that the large interspace is filled with water and results from strong repulsive forces between the positively charged lipid bilayers. The hypothesis of a unit cell with two lipid bilayers is described in the literature for different systems of mixed lipids. , However, one condition is that both bilayers showed different properties: e.g., each one consisted of a different amphiphile. In the present case, structural differences in single component systems are not reasonable whereas the hypothesis of an extended water layer between the lipid bilayers is more favored.…”

Section: Results and Discussionmentioning

confidence: 99%

Interactions of Cationic Lipids with DNA: A Structural Approach

Dittrich

Brauer

Funari³

et al. 2018

Langmuir

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Colloidal nucleic acid carrier systems based on cationic lipids are a promising pharmaceutical tool in the implementation of gene therapeutic strategies. This study demonstrates the complex behavior of DNA at the lipid-solvent interface facilitating structural changes of the lyotropic liquid-crystalline phases. For this study, the structural properties of six malonic acid based cationic lipids were determined using small- and wide-angle X-ray scattering (SAXS and WAXS) as well as differential scanning calorimetry (DSC). Selected lipids (lipid 3 and lipid 6) with high nucleic acid transfer activity have been investigated in detail because of the strong influence of the zwitterionic helper lipid 1,2-di(9 Z-octadecenoyl)- sn-glycero-3-phosphoethanolamine (DOPE) on the structural properties as well as of the complex formation of lipid-DNA complexes (lipoplexes). In the case of lipid 3, DNA stabilizes a metastable cubic mesophase with Im3 m symmetry and an Im3 m Q lipoplex is formed, which is rarely described for DNA lipoplexes in literature. In the case of lipid 6, a cubic mesophase with Im3 m symmetry turns into a fluid lamellar phase while mixing with DOPE and complexing DNA.

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Double-bilayer: a new phase formed by lysophospholipids and the corresponding fatty acid

Cited by 9 publications

References 15 publications

Unravelling a Mechanism of Action for a Cecropin A-Melittin Hybrid Antimicrobial Peptide: The Induced Formation of Multilamellar Lipid Stacks

Unravelling a Mechanism of Action for a Cecropin A-Melittin Hybrid Antimicrobial Peptide: The Induced Formation of Multilamellar Lipid Stacks

Effect of urea and tmao on lipid bilayers

Interactions of Cationic Lipids with DNA: A Structural Approach

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