Effects of charged cholesteryl esters on mycoplasma growth

Efrati, Hava; Shinitzky, Meir; Razin, Shmuel

doi:10.1016/0014-5793(80)80401-7

Cited by 7 publications

(2 citation statements)

References 14 publications

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“…The esters cholesterol hemisuccinate and cholesterol betainate have been used in this way (Heron et al, 1980;Efrati et al, 1980;Yuli et al, 1981). Here we characterize the interaction between cholesterol hemisuccinate and lipid bilayers and use the fluorescence quenching properties of brominated derivatives of phospholipids and cholesterol hemisuccinate to study binding to the (Ca2+-Mg2+)-ATPase purified from sarcoplasmic reticulum of rabbit skeletal muscle.…”

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confidence: 99%

Interactions of cholesterol hemisuccinate with phospholipids and calcium-magnesium ATPase

Simmonds¹,

Rooney²,

Lee³

1984

Biochemistry

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Cholesterol hemisuccinate has been shown to equilibrate readily with liposomes and with the (Ca2+-Mg2+)-ATPase from sarcoplasmic reticulum and has been used to modify the sterol content of these membranes. Cholesterol hemisuccinate incorporates into dioleoylphosphatidylcholine (DOPC) up to a molar ratio of 3:1 sterol to DOPC. Effects on lipid order as detected by electron spin resonance and fluorescence polarization are comparable to those of cholesterol. Binding constants have been determined, and the uncharged form of the sterol binds more strongly than the anionic form. Binding to DOPC and to the lipid component of the ATPase system is comparable. From use of the fluorescence quenching properties of 1,2-bis(9,10- dibromooleoyl )phosphatidylcholine and dibromocholesterol hemisuccinate, two classes of binding sites on the ATPase have been deduced. At the lipid/protein interface, the binding constant for cholesterol hemisuccinate is considerably less than that for DOPC. At the second set of sites ( nonannular sites), binding occurs with Kd = 0.55 in molar ratio units. The effect of cholesterol hemisuccinate on the activity of the ATPase depends on the phospholipid present in the system: ATPase reconstituted with DOPC is inhibited whereas ATPase reconstituted with dimyristoleoylphosphatidylcholine is activated. We conclude that changes in membrane fluidity are not important in determining ATPase activity in these systems.

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confidence: 99%

Interactions of cholesterol hemisuccinate with phospholipids and calcium-magnesium ATPase

Simmonds¹,

Rooney²,

Lee³

1984

Biochemistry

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“…Chemical analyses of the cells revealed several age-related alterations, mainly a surprisingly high content of cholesteryl esters in membranes and the accumulation of organic peroxides. Sterol-requiring mycoplasmas are unable to esterify free cholesterol (5,30), and in most cases, cholesteryl esters are incorporated unchanged from the growth medium (8). The association of cholesteryl esters with S. floricola membranes appears to be tight, as successive washings of intact cells with 0.5 M NaCl did not release any cholesteryl esters from the membranes.…”

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confidence: 99%

Fusion of Spiroplasma floricola cells with small unilamellar vesicles is dependent on the age of the culture

1993

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Small unilamellar vesicles were labeled with the fluorescent probe octadecylrhodamine B chloride and mixed with intact Spiroplasma floricola cells. The increase in fluorescence observed was interpreted as a result of the dilution of the probe in the unlabeled S. floricola membranes because of lipid mixing upon fusion. The progression of S. floricola cultures to the stationary phase of growth was accompanied by a sharp decrease in the ability of the cells to fuse with small unilamellar vesicles. Low fusogenic activity was also detected in cells from cultures that were aged in a growth medium maintained at pH 7.5 throughout the growth cycle. Chemical analysis of the cell membrane preparations isolated from cells harvested at the various phases of growth revealed that the phospholipid content and composition and the cholesterol/phospholipid molar ratio were changed very little upon aging of the cultures. Likewise, no changes in the fatty acid composition of membrane lipids were detected, with palmitic and oleic acids predominating throughout the cycle. Nonetheless, upon aging of S. floricola cultures, a pronounced increase in the levels of both cholesteryl esters, incorporated from the growth medium, and organic peroxides was observed. A decrease in both fluorescence anisotropy of diphenylhexatriene and merocyanine 540 binding to membranes of aged cells was also detected. The possible influence of these changes on the fusogenic activity of the cells is discussed.We recently demonstrated that Mycoplasma capricolum and Spiroplasma floricola cells are capable of fusing with lipid vesicles (25,26,31). This observation opened the way for the development of a fusion-mediated system for the delivery of genetic material into S. floricola cells (26). Nonetheless, exponential-phase cells showed high fusion activity, whereas low fusion activity was obtained with stationary-phase cells (26). It was therefore suggested that the fusion activity of S. floricola cells depends upon the growth phase of the culture. The low fusion activity of aged S. floricola cells may reflect changes in the chemical composition and biophysical characteristics of the cell membranes upon aging. Changes in the ratios of phospholipid to protein, saturated to unsaturated fatty acids, and phosphatidylglycerol (PG) to diphosphatidylglycerol (DPG) in the cell membranes upon aging of Acholeplasma laidlawii (11, 12), M. hominis (20), M. capricolum (10), and M. canadense cells (16) have been reported elsewhere.Mycoplasmas and spiroplasmas are fatty acid and cholesterol auxotrophs (17, 18), requiring a mixture of saturated and unsaturated fatty acids as well as unesterified cholesterol for growth. The de novo-synthesized phospholipids of these organisms are rather simple, being composed primarily of negatively charged phospholipids, such as PG and DPG (18,30). When the organisms are grown in a serum-containing medium, significant amounts of exogenous lipids, mainly phosphatidylcholine (PC), sphingomyelin (SPM), and cholesteryl esters, are incorporated into the...

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Mycoplasma Membrane Lipids Chemical Composition and Transbilayer Distribution

Bittman

1993

Subcellular Biochemistry

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Effects of charged cholesteryl esters on mycoplasma growth

Cited by 7 publications

References 14 publications

Interactions of cholesterol hemisuccinate with phospholipids and calcium-magnesium ATPase

Interactions of cholesterol hemisuccinate with phospholipids and calcium-magnesium ATPase

Fusion of Spiroplasma floricola cells with small unilamellar vesicles is dependent on the age of the culture

Mycoplasma Membrane Lipids Chemical Composition and Transbilayer Distribution

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