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Sphingomyelin modulates the transbilayer distribution of galactosylceramide in phospholipid membranes.

ABSTRACT: The interrelationships among sphingolipid structure, membrane curvature, and glycosphingolipid transmembrane distribution remain poorly defined despite the emerging importance of sphingolipids in curved regions and vesicle buds of biomembranes. Here, we describe a novel approach to investigate the transmembrane distribution of galactosylceramide in phospholipid small unilamellar vesicles by (13)C NMR spectroscopy. Quantitation of the transbilayer distribution of [6-(13)C]galactosylceramide (99.8% isotopic enrichment) was achieved by exposure of vesicles to the paramagnetic ion, Mn(2+). The data show that [6-(13)C]galactosylceramide prefers (70%) the inner leaflet of phosphatidylcholine vesicles. Increasing the sphingomyelin content of the 1-palmitoyl-2-oleoyl-phosphatidylcholine vesicles shifted galactosylceramide from the inner to the outer leaflet. The amount of galactosylceramide localized in the inner leaflet decreased from 70% in pure 1-palmitoyl-2-oleoyl-phosphatidylcholine vesicles to only 40% in 1-palmitoyl-2-oleoyl-phosphatidylcholine/sphingomyelin (1:2) vesicles. The present study demonstrates that sphingomyelin can dramatically alter the transbilayer distribution of a monohexosylceramide, such as galactosylceramide, in 1-palmitoyl-2-oleoyl-phosphatidylcholine/sphingomyelin vesicles. The results suggest that sphingolipid-sphingolipid interactions that occur even in the absence of cholesterol play a role in controlling the transmembrane distributions of cerebrosides.

SUBMITTER: Mattjus P

PROVIDER: S-EPMC2612996 | biostudies-literature | 2002 May

REPOSITORIES: biostudies-literature

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Sphingomyelin modulates the transbilayer distribution of galactosylceramide in phospholipid membranes.

Mattjus Peter P Malewicz Barbara B Valiyaveettil Jacob T JT Baumann Wolfgang J WJ Bittman Robert R Brown Rhoderick E RE

The Journal of biological chemistry 20020321 22

The interrelationships among sphingolipid structure, membrane curvature, and glycosphingolipid transmembrane distribution remain poorly defined despite the emerging importance of sphingolipids in curved regions and vesicle buds of biomembranes. Here, we describe a novel approach to investigate the transmembrane distribution of galactosylceramide in phospholipid small unilamellar vesicles by (13)C NMR spectroscopy. Quantitation of the transbilayer distribution of [6-(13)C]galactosylceramide (99.8 ...[more]

PMID: 11909867

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Project description:The focus of this work is to elucidate how phospholipid composition can modulate lipid nanoparticle interactions in phospholipid monolayer systems. We report on alterations in lipid domain formation induced by anionically engineered carbon nanodiamonds (ECNs) as a function of lipid headgroup charge and alkyl chain saturation. Using surface pressure vs area isotherms, monolayer compressibility, and fluorescence microscopy, we found that anionic ECNs induced domain shape alterations in zwitterionic phosphatidylcholine lipids, irrespective of the lipid alkyl chain saturation, even when the surface pressure vs area isotherms did not show any significant changes. Bean-shaped structures characteristic of dipalmitoylphosphatidylcholine (DPPC) were converted to multilobed, fractal, or spiral domains as a result of exposure to ECNs, indicating that ECNs lower the line tension between domains in the case of zwitterionic lipids. For membrane systems containing anionic phospholipids, ECN-induced changes in domain packing were related to the electrostatic interactions between the anionic ECNs and the anionic lipid headgroups, even when zwitterionic lipids are present in excess. By comparing the measured size distributions with our recently developed theory derived by minimizing the free energy associated with the domain energy and mixing entropy, we found that the change in line tension induced by anionic ECNs is dominated by the charge in the condensed lipid domains. Atomic force microscopy images of the transferred anionic films confirm that the location of the anionic ECNs in the lipid monolayers is also modulated by the charge on the condensed lipid domains. Because biological membranes such as lung surfactants contain both saturated and unsaturated phospholipids with different lipid headgroup charges, our results suggest that when studying potential adverse effects of nanoparticles on biological systems the role of lipid compositions cannot be neglected.

Dataset Information

Sphingomyelin modulates the transbilayer distribution of galactosylceramide in phospholipid membranes.

Publications

Sphingomyelin modulates the transbilayer distribution of galactosylceramide in phospholipid membranes.

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