Cholesterol uptake capacity of Acholeplasma laidlawii is affected by the composition and content of membrane glycolipids

Efrati, Hava; Wax, Yohanan; Rottem, Shlomo

doi:10.1016/0003-9861(86)90425-x

Cited by 15 publications

(7 citation statements)

References 22 publications

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“…Our results do indeed indicate that the nature of the interaction of cholesterol with each of the major A. laidlawii membrane lipids differs considerably. Specifically, we find the apparent miscibility of cholesterol with the neutral glycolipids of this organism to be lower than with the major phospholipid, lending support to the hypothesis of Efrati et al (1986), and to the possibility that the relative immiscibility of cholesterol in the neutral glycolipids may account for the presence of solid-like, laterally segregated, cholesterol-enriched domains in the membranes of this organism (Monck et al, 1993).…”

supporting

confidence: 70%

“…In this regard, note that the reduction in the phase transition temperature of the higher melting MGDG component is considerably greater than that of the lower melting DGDG component of identical fatty acid composition, as predicted from their relative phase transition temperatures. Efrati et al (1986) have proposed that the difference in the exogenous cholesterol incorporation capacities of Acholeplasma and Mycoplasma species may be due to the much higher membrane neutral glycolipid contents of the former and to a reduced capacity of glycolipids to solubilize cholesterol. This proposal was supported by a statistical analysis of a large number of Acholeplasma species and strains which revealed a significant negative correlation between the glycolipid content of the cell membrane and the level of incorporation of cholesterol by growing cells.…”

Section: Discussionmentioning

confidence: 99%

“…The sterol-non-requiring mycoplasmas such as A. laidlawii generally contain large quantities of neutral glycolipids, primarily mono-and diglycosyldiacylglycerols, whereas these neutral glycolipids are much reduced or absent in the sterolrequiring mycoplasmas. Efrati et al (1986) have proposed that the lower levels of exogenous cholesterol incorporation characteristic of the sterol-non-requiring mycoplasmas may be due to their elevated glycolipid content and to a reduced capacity of these glycolipids to incorporate sterols. Moreover, the relatively stronger affinity of cholesterol for phospholipids and its relatively weaker affinity for glycolipids have been invoked to explain the existence of two separate pools of cholesterol which exchange with different kinetics in A. laidlawii membrane/liposomal systems (Davis et al, 1984) and which may exist in two different physical states (Monck et al, 1993).…”

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confidence: 99%

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Differential Scanning Calorimetric Study of the Interaction of Cholesterol with the Major Lipids of the Acholeplasma laidlawii B Membrane

et al. 1996

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It has been proposed that the lower levels of exogenous cholesterol incorporation into the membranes of the sterol-non-requiring as compared to the sterol-requiring mycoplasmas may be due to the much higher glycolipid content of the former and to the reduced ability of glycolipids, as opposed to phospholipids, to incorporate sterols [Efrati et al. (1986) Arch. Biochem. Biophys. 248, 282-288]. In order to test this hypothesis, we have investigated the interaction of cholesterol with the major membrane glyco- and phospholipids of the sterol-non-requiring mycoplasma Acholeplasma laidlawii B, utilizing elaidic acid-homogenous membranes in order to obviate any differences in the nature of cholesterol-lipid interactions due to variations in the fatty acid composition of the different membrane components. Specifically, we have studied the effect of increasing quantities of cholesterol on the thermotropic phase behavior of aqueous dispersions of phosphatidylglycerol, diglucosyl diacylglycerol, and monoglucosyl diacylglycerol, as well as the total membrane polar lipids of this organism, using high-sensitivity differential scanning calorimetry. We find that cholesterol is highly miscible in both the lamellar gel and liquid-crystalline states of phosphatidylglycerol but exhibits limited miscibility in the two neutral glycolipids, particularly in their lamellar gel and crystalline states. We also demonstrate that cholesterol has a limited miscibility in both the lamellar gel and liquid-crystalline states of bilayers composed of the total A. laidlawii B membrane polar lipids. These results demonstrate that the nature of cholesterol-lipid interactions depends markedly on the structure of the glycerolipid polar headgroup and suggests that the incorporation of lower levels of cholesterol into the membranes of the sterol-non-requiring mycoplasmas may indeed be due, at least in part, to their high glycolipid contents. We also show that cholesterol stabilizes the lamellar liquid-crystalline phase of the monoglucosyl diacylglycerol relative to the inverted hexagonal phase at all sterol concentrations, in contrast to the effects of cholesterol on dielaidoylphosphatidylethanolamine, which destabilizes the lamellar liquid-crystalline phase at low concentrations.

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confidence: 70%

Section: Discussionmentioning

confidence: 99%

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Differential Scanning Calorimetric Study of the Interaction of Cholesterol with the Major Lipids of the Acholeplasma laidlawii B Membrane

et al. 1996

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“…It is known that sterols have a low solubility in glycolipids (55). We next included both DGDG and stigmasterol in phospholipid liposomes to test our hypothesis that the low content of DGDG in the apoplastic plasma membrane leaflet would be related to its incompatibility with high levels of nonmodified sterols.…”

Section: Dgdg Is Restricted To the Cytosolic Leaflet Of Oat Root Plasmentioning

confidence: 99%

Lipid asymmetry in plant plasma membranes: phosphate deficiency‐induced phospholipid replacement is restricted to the cytosolic leaflet

et al. 2009

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As in other eukaryotes, plant plasma membranes contain sphingolipids, phospholipids, and free sterols. In addition, plant plasma membranes also contain sterol derivatives and usually <5 mol% of a galactolipid, digalactosyldiacylglycerol (DGDG). We earlier reported that compared to fully fertilized oats (Avena sativa), oats cultivated without phosphate replaced up to 70 mol% of the root plasma membrane phospholipids with DGDG. Here, we investigated the implications of a high DGDG content on membrane properties. The phospholipid-to-DGDG replacement almost exclusively occurred in the cytosolic leaflet, where DGDG constituted up to one-third of the lipids. In the apoplastic (exoplasmic) leaflet, as well as in rafts, phospholipids were not replaced by DGDG, but by acylated sterol glycosides. Liposome studies revealed that the chain ordering in free sterol/phospholipid mixtures clearly decreased when >5 mol% DGDG was included. As both the apoplastic plasma membrane leaflet (probably the major water permeability barrier) and rafts both contain only trace amounts of DGDG, we conclude that this lipid class is not compatible with membrane functions requiring a high degree of lipid order. By not replacing phospholipids site specifically with DGDG, negative functional effects of this lipid in the plasma membrane are avoided.-Tjellström, H., Hellgren, L. I., Wieslander, A., Sandelius, A. S. Lipid asymmetry in plant plasma membranes: phosphate deficiency-induced phospholipid replacement is restricted to the cytosolic leaflet.

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“…Many studies of biomembrane structure and function relationships have been performed by using mycoplasmas as models (1,2,17). Similar to eucaryotic cells (4), mycoplasmas incorporate sterols into their membranes, and several species of mycoplasma are the only procaryotes known to have an absolute requirement for cholesterol (8,22).…”

mentioning

confidence: 99%

Cytotoxic and cytolytic activity of nonadecafluoro-n-decanoic acid on Acholeplasma laidlawii

Liss¹,

Pfeil²,

Levitt³

1987

Appl Environ Microbiol

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We studied the interactions between the perfluorinated fatty acid nonadecafluoro-n-decanoic acid (NDFDA) and the cell wall-less procaryote Acholeplasma laidlawii, which were cultured in an identical medium base but with different serum supplements. When grown in mycoplasma media supplemented with PPLO serum fraction (Difco Laboratories, Detroit, Mich.), A. laidlawii was rapidly killed by low concentrations of toxicant (<1.0 mM). At higher concentrations (>10 mM), NDFDA treatment appeared to lyse cells. A. laidlawii cells grown in horse serum-supplemented mycoplasma media were both killed and lysed at the same NDFDA concentration (>10 mM). These data suggest that this perfluorinated fatty acid can be cytotoxic and cytolytic to mycoplasmas. Changes in active concentrations occurred in parallel with changes in growth medium serum supplementation, which is known to alter mycoplasma membrane composition. We propose that NDFDA interacts with the membranes of A. laidlawii cells, resulting in cell death or cell lysis or both.

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Cholesterol uptake capacity of Acholeplasma laidlawii is affected by the composition and content of membrane glycolipids

Cited by 15 publications

References 22 publications

Differential Scanning Calorimetric Study of the Interaction of Cholesterol with the Major Lipids of the Acholeplasma laidlawii B Membrane

Differential Scanning Calorimetric Study of the Interaction of Cholesterol with the Major Lipids of the Acholeplasma laidlawii B Membrane

Lipid asymmetry in plant plasma membranes: phosphate deficiency‐induced phospholipid replacement is restricted to the cytosolic leaflet

Cytotoxic and cytolytic activity of nonadecafluoro-n-decanoic acid on Acholeplasma laidlawii

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