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Interaction of earthworm hemolysin with lipid membranes requires sphingolipids

Item Type:Article
Title:Interaction of earthworm hemolysin with lipid membranes requires sphingolipids
Creators Name:Lange, S. and Nuessler, F. and Kauschke, E. and Lutsch, G. and Cooper, E.L. and Herrmann, A.
Abstract:Lytic activity in the coelomic fluid of earthworm (Eisenia fetida fetida) has been ascribed to eiseniapore, a hemolytic protein of 38 kDa. Since receptors for eiseniapore on target cell membranes are not known, we used lipid vesicles of various composition to determine whether specific lipids may serve as receptors. Lytic activity of eiseniapore was probed by the relief of fluorescence dequenching from the fluorophore 8-aminonaphthalene-1,3, 6-trisulfonic acid originally incorporated into the vesicle lumen as a complex with p-xylene-bis-pyridinium bromide. Hemolysin binds to and disturbs the lipid bilayer only when distinct sphingolipids consisting of a hydrophilic head group as phosphorylcholine or galactosyl as well as the ceramide backbone, e.g. sphingomyelin, are present. Cholesterol enhances eiseniapore lytic activity toward sphingomyelin-containing vesicles probably due to interaction with sphingomyelin. Leakage of vesicles was most efficient when the lipid composition resembled that of the outer leaflet of human erythrocytes. Presumably, an oligomeric protein pore formed by six monomers is responsible for leakage of sphingomyelin-containing vesicles. The secondary structure of eiseniapore did not change upon binding to lipid membranes. The lytic activity of eiseniapore was completely abolished after its denaturation or after preincubation with polyclonal antibodies. Our results suggest that the presence of specific sphingolipids is sufficient to mediate lytic activity of eiseniapore. This action contributes to our understanding of earthworm immune responses.
Keywords:Erythrocyte Membrane, Hemolysin Proteins, Liposomes, Secondary Protein Structure, Sphingolipids, Animals, Oligochaeta
Source:Journal of Biological Chemistry
Publisher:American Society for Biochemistry and Molecular Biology
Page Range:20884-20892
Date:15 August 1997
Official Publication:https://doi.org/10.1074/jbc.272.33.20884
PubMed:View item in PubMed

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