Interaction of Amoebapores and NK-Lysin with Symmetric Phospholipid and Asymmetric Lipopolysaccharide/Phospholipid Bilayers

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• 作者：Thomas Gutsmann ; Beate Riekens ; Heike Bruhn ; Andre Wiese ; Ulrich Seydel ; and Matthias Leippe
• 刊名：Biochemistry
• 出版年：2003
• 出版时间：August 19, 2003
• 年：2003
• 卷：42
• 期：32
• 页码：9804 - 9812
• 全文大小：155K
• 年卷期：v.42,no.32(August 19, 2003)
• ISSN：1520-4995

文摘

Amoebapores from protozoan parasite Entamoeba histolytica and NK-lysin of porcine cytotoxiclymphocytes belong to the same family of saposin-like proteins. In addition to the structural similarity,amoebapores and NK-lysin are both highly effective against prokaryotic and eukaryotic target cells inthat they permeabilize the target cell membranes. Here, we have investigated in detail the protein/lipidinteraction for the three isoforms of amoebapore and NK-lysin. Results obtained from electricalmeasurements on planar bilayer membranes, including reconstitution models of the lipid matrix of theouter membrane of Escherichia coli and phospholipid membranes, fluorescence energy transfer spectroscopywith liposomes, and monolayer measurements on a Langmuir trough, provided information on lipidpreferences, pH dependences, and membrane interaction mechanisms. The three amoebapores led to theformation of transient pores with similar characteristics in conductance, sublevels, and lifetime for thedifferent isoforms. The conductance of the pores was dependent on the polarity of the applied clampvoltage, and the distribution of the sublevels was affected by the value of the clamp voltage. The size ofthe pores and distribution of conductance sublevels differed between symmetric phospholipid andasymmetric lipopolysaccharide/phospholipid bilayers. Notably, NK-lysin caused the formation of well-defined pores, which were lipid- and voltage-dependent, and their characteristics differed from those inducedby amoebapores; e.g., the protein concentration necessary to induce pore formation was 20 times higher.The biophysical data give important information on the mode of action of these small effector proteins,which may further lead to a better understanding of peptide-membrane interactions in general.