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  • Title: Physicochemical characterization and biological activity of a glycoglycerolipid from Mycoplasma fermentans.
    Author: Brandenburg K, Wagner F, Müller M, Heine H, Andrä J, Koch MH, Zähringer U, Seydel U.
    Journal: Eur J Biochem; 2003 Aug; 270(15):3271-9. PubMed ID: 12869203.
    Abstract:
    We report a comprehensive physicochemical characterization of a glycoglycerolipid from Mycoplasma fermentans, MfGl-II, in relation to its bioactivity and compared this with the respective behaviors of phosphatidylcholine (PC) and a bacterial glycolipid, lipopolysaccharide (LPS) from deep rough mutant Salmonella minnesota strain R595. The beta left arrow over right arrow alpha gel-to-liquid crystalline phase transition behavior of the hydrocarbon chains with Tc = 30 degrees C for MfGl-II as well as for LPS exhibits high similarity between the two glycolipids. A lipopolysaccharide-binding protein (LBP)-mediated incorporation into negatively charged liposomes is observed for both glycolipids. The determination of the supramolecular aggregate structure confirms the existence of a mixed unilamellar/cubic structure for MfGl-II, similar to that observed for the lipid A moiety of LPS. The biological data clearly show that MfGl-II is able to induce cytokines such as tumor necrosis factor-alpha (TNF-alpha) in human mononuclear cells, although to a significantly lower degree than LPS. In contrast, in the Limulus amebocyte lysate test, MfGl-II is completely inactive, and in the CHO reporter cell line it does not indicate any reactivity with the Toll-like receptors TLR-2 and -4, in contrast to control lipopeptides and LPS. These data confirm the applicability of our conformational concept of endotoxicity to nonlipid A structures: an amphiphilic molecule with a nonlamellar cubic aggregate structure corresponding to a conical conformation of the single molecules and a sufficiently high negative charge density in the backbone.
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