Dataset Information

The dependence of lipid asymmetry upon polar headgroup structure.

ABSTRACT: The effect of lipid headgroup structure upon the stability of lipid asymmetry was investigated. Using methyl-?-cyclodextrin -induced lipid exchange, sphingomyelin (SM) was introduced into the outer leaflets of lipid vesicles composed of phosphatidylglycerol, phosphatidylserine (PS), phosphatidylinositol, or cardiolipin, in mixtures of all of these lipids with phosphatidylethanolamine (PE), and in a phosphatidylcholine/phosphatidic acid mixture. Efficient SM exchange (>85% of that expected for complete replacement of the outer leaflet) was obtained for every lipid composition studied. Vesicles containing PE mixed with anionic lipids showed nearly complete asymmetry which did not decay after 1 day of incubation. However, vesicles containing anionic lipids without PE generally only exhibited partial asymmetry, which further decayed after 1 day of incubation. Vesicles containing the anionic lipid PS were an exception, showing nearly complete and stable asymmetry. It is likely that the combination of multiple charged groups on PE and PS inhibit transverse diffusion of these lipids across membranes relative to those lipids that only have one anionic group. Possible explanations of this behavior are discussed. The asymmetry properties of PE and PS may explain some of their functions in plasma membranes.

SUBMITTER: Son M

PROVIDER: S-EPMC3826685 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

The dependence of lipid asymmetry upon polar headgroup structure.

Son Mijin M London Erwin E

Journal of lipid research 20131007 12

The effect of lipid headgroup structure upon the stability of lipid asymmetry was investigated. Using methyl-β-cyclodextrin -induced lipid exchange, sphingomyelin (SM) was introduced into the outer leaflets of lipid vesicles composed of phosphatidylglycerol, phosphatidylserine (PS), phosphatidylinositol, or cardiolipin, in mixtures of all of these lipids with phosphatidylethanolamine (PE), and in a phosphatidylcholine/phosphatidic acid mixture. Efficient SM exchange (>85% of that expected for co ...[more]

PMID: 24101657

Similar Datasets

Project description:Ceramide is a major actor in the sphingolipid signaling pathway elicited by various kinds of cell stress. Under those conditions ceramide (Cer) is produced in the plasma membrane as a product of sphingomyelin (SM) hydrolysis, and this may lead to apoptosis. Thus, SM and Cer coexist in the membrane for some time, and they are known to separate laterally from the (more abundant) glycerolipids, giving rise to highly rigid domains or platforms. The properties of these domains/platforms are rather well understood, but the underlying SM:Cer molecular interactions have not been explored in detail. Infrared (IR) spectroscopy is a powerful analytical technique that provides information on all the chemical groupings in a molecule, and that can be applied to membranes and lipid bilayers in aqueous media. IR spectra can be conveniently retrieved as a function of temperature, thus revealing the thermotropic transitions of SM and its mixtures with Cer. Four regions of the IR spectrum of these sphingolipids have been examined, two of them dominated by the hydrophobic regions in the molecules, namely the C-H stretching vibrations (2800-3000 cm-1), and the CH2 scissoring vibrations (1455-1485 cm-1), and two others arising from chemical groups at the lipid-water interface, the sphingolipid amide I band (1600-1680 cm-1), and the phosphate vibrations in the 1000-1110 cm-1 region. The latter two regions have been rarely studied in the past. The IR data from the hydrophobic components show a gel (or ripple)-fluid transition of SM at 40 °C, that is shifted up to about 70 °C when Cer is added to the bilayers, in agreement with previous studies using a variety of techniques. IR information concerning the polar parts is more interesting. The amide I (carbonyl) band of pure SM exhibits a maximum at 1638 cm-1 at room temperature, and its position is shifted by about 10 cm-1 in the presence of Cer. Cer causes also a change in the overall band shape, but no signs of band splitting are seen, suggesting that SM and Cer carbonyl groups are interacting tightly, presumably through H-bonds. The 1086 cm-1 band, corresponding to PO2- vibrations, appears more stable in SM than in DPPC, and it is further stabilized by Cer, again suggesting an important role of H-bonds in the formation of SM:Cer clusters. Thus, SM and Cer can interact through their polar headgroups, in a way that is not accessible to other lipid classes.

Dataset Information

The dependence of lipid asymmetry upon polar headgroup structure.

Publications

The dependence of lipid asymmetry upon polar headgroup structure.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets