Ultrastructural visualization of anionic sites on mycoplasma membranes by polycationic ferritin

Schiefer, Hans-Gerd; Krauss, H; Brünner, Helmut; Gerhardt, Ursula

doi:10.1128/jb.127.1.461-468.1976

Cited by 39 publications

(13 citation statements)

References 35 publications

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“…The external location of at least some of the mycoplasma membrane phospholipids has been suggested by electron microscopy with ferric oxide hydrosols in propanoic acid (284) or polycationic ferritin (283) that bind to negatively charged groups on the membrane surface. The anionic sites appear to be lipid phosphate groups rather than protein carboxyls, since extraction of the membranes with lipid solvents abolished labeling, whereas Pronase treatment increased labeling (283,284). Striking membrane asymmetry was detected on labeling of isolated membranes of M. mycoides subsp.…”

Section: Membrane Lipidsmentioning

confidence: 99%

“…The probe was found to bind to one membrane surface only, prewsmably the outer one (283). On the other hand, M. hominis membranes, even when isolated from cells, failed to react with the iron-containing labels unless membrane protein was first digested by Pronase (283). This is in accordance with previous findings showing that the major phospholipid of the M. hominis membrane, phosphatidylglyceroL resists hydrolysis by phospholipase C (266) and fails to interact with its specific antiserum (280) unless the membranes are first treated with Pronase, suggesting that membrane phospholipids in M. hominis are masked by proteins on both membrane sides.…”

Section: Membrane Lipidsmentioning

confidence: 99%

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The mycoplasmas.

Razin¹

1978

Microbiological Reviews

218

135

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Section: Membrane Lipidsmentioning

confidence: 99%

Section: Membrane Lipidsmentioning

confidence: 99%

The mycoplasmas.

Razin¹

1978

Microbiological Reviews

218

135

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“…It is possible that interaction between A. laidlawii cells and liposomes occur as a result of a combination of hydrogen bonding and electrostatic forces. Schiefer et al (1976) showed that the net negative charge on the surface of Acholeplasma cells and that anionic sites were uniformly distributed over the entire membrane surface, although PC is a zwitterion (i.e. carries both positive and negative charges), the positive charge carried in the choline moiety will be on the surface of the molecule, thus making electrostatic adherence between acholeplasma cells and liposomes possible.…”

Section: Discussionmentioning

confidence: 99%

Alternative to fluorescence assays to monitor fusion between Acholeplasma laidlawii cells and liposomes

Abu-Amero

Halablab

Milès

2002

Lett Appl Microbiol

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Aims: To develop a new technique as an alternative to the fluorescence assays and electron microscopy for the purpose of monitoring the cell-liposome fusion. Methods and Results: Acholeplasma laidlawii whole cells did not oxidize Glucose-6-phosphate (G6P) or Fructose-1,6 diphosphate (F1,6DP) as free (unentrapped) substrates, at concentrations 47 and >270 mM, respectively. Lysed A. laidlawii cells oxidized G6P and F1,6DP at lower concentration of 0AE8 and 15 mM, respectively. When these substrates were entrapped inside liposomes, at a final concentration of 1AE5 mM, and interacted with A. laidlawii whole cells, in an oxygen electrode chamber, an increase in oxygen uptake was evident. This interaction does not have any effect on cell viability. Significance and Impact of the study: The experimental system described here is advantageous over classical fluorescence assays in determining the fate of liposome-entrapped material and raises the possibility of studying the kinetics of metabolic substrates, which are normally excluded from the cell by the cell membrane.

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“…Using polycationic ferritin or positively charged ferric oxide hydrosols in propionic acid as probes, we have demonstrated by electron microscopy a dense and rather homogeneous layer of anionic binding sites on the membrane surface of A. laidlawii. With chemical and enzymatic techniques, the anionic sites were identified to be mainly lipid phosphate groups of, e.g., phosphatidylglycerol (32,33).…”

Section: Effect Of Gps On Viability Of a Laidlawiimentioning

confidence: 99%

Antibodies to Acholeplasma laidlawii membrane lipids in normal guinea pig serum

Dorner¹,

Brünner²,

Schiefer³

et al. 1977

Infect Immun

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Acholeplasma laidlawii is killed and lysed by fresh normal guinea pig serum (GPS) without additional antibodies. Prior incubation of GPS with whole A. laidlawii organisms abolishes the killing activity of GPS. In the present study it was demonstrated that antibodies are present in normal GPS. The classical pathway, not the alternative pathway, of the complement sequence was activated by these antibodies in fresh normal GPS. The antibodies in GPS belong to the IgG class of immunoglobulins. They are directed predominantly against the membrane phospholipids ofA. laidlawii. These antibodies may be induced either by natural infection of guinea pigs with A. laidlawii or by antigenic determinants of other microorganisms or food antigens.In recent years it has been clearly demonstrated that some mycoplasmas are killed and lysed by the combined action of antibodies and complement (1,6,8,12,15,20,24,25,34). Fresh normal guinea pig serum (GPS) has been most frequently used as the source of complement in these experiments. In studies on immune lysis of Mycoplasma pneumoniae it was noted that GPS by itself, without addition of antibodies, reduced the number of viable organisms. As had been reported by Gale and Kenny (15), Sethi and Teschner (34), and from our laboratory (8), removal of the growth-inhibitory substances from GPS by absorption with killed M. pneumoniae was not possible. Nevertheless, the possibility that small amounts of antibodies to M. pneumoniae, not detectable by our methods, were present in normal GPS could not be excluded.It has been recently shown by Bredt and Bitter-Suermann (4) that M. pneumoniae can activate the guinea pig complement system via the altemnative pathway. This activation results in rounding of the organisms. Efficient killing requires, in addition, the entire complement sequence. It was also shown that M. pneumoniae can interact directly with Cl in the absence of detectable amounts of antibodies (5).We have previously demonstrated that a decrease in viability of Acholeplasma laidlawii occurs when the organisms are incubated with fresh GPS (11). In this publication, data are pret Present address: sented indicating that antibodies of the immunoglobulin G (IgG) class can be detected in normal GPS. These antibodies are directed against the membrane lipids of the organisms and activate preferentially the classical pathway of complement.(These results were presented in a preliminary form at the Annual Meeting of the American Society for Microbiology, New York, 1975, and the Arbeitstagung der Deutschen Gesellschaft ftir Hygiene und Mikrobiologie, Mainz, West Germany, 1976).MATERIALS AND METHODS Organisms and growth media. A. laidlawii, oral strain, and M. pneumoniae, strain PI 1428, originally obtained from R. M. Chanock, Bethesda, Md., were used. A. laidlawii had been subcultured several times on artificial medium. M. pneumoniae was used in its sixth passage on growth medium (9,11).The medium for A. laidlawii consisted of 350 ml of PPLO broth (Difco Laboratories, Detroit, Mich.) supplemented wi...

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Ultrastructural visualization of anionic sites on mycoplasma membranes by polycationic ferritin

Cited by 39 publications

References 35 publications

The mycoplasmas.

The mycoplasmas.

Alternative to fluorescence assays to monitor fusion between Acholeplasma laidlawii cells and liposomes

Antibodies to Acholeplasma laidlawii membrane lipids in normal guinea pig serum

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