Voltage-dependent depolarization of bacterial membranes and artificial lipid bilayers by the peptide antibiotic nisin |
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Authors: | H -G Sahl M Kordel R Benz |
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Institution: | (1) Institut für Med. Mikrobiologie und Immunologie der Universität Bonn, Venusberg, D-5300 Bonn 1, Germany;(2) Lehrstuhl für Biotechnologie der Universität Würzburg, Röntgenring 11, D-8700 Würzburg, Germany;(3) Present address: Gesellschaft für Biotechnologische Forschung, Mascheroder Weg 1, D-3300 Braunschweig, Germany |
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Abstract: | The peptide antibiotic nisin is shown to disrupt valinomycin-induced potassium diffusion potentials imposed on intact cells of Staphylococcus cohnii 22. Membrane depolarization occurred rapidly at high diffusion potentials while at low potentials nisin-induced depolarization was slower suggesting that nisin requires a membrane potential for activity. This assumption was proven in experiments with planar lipid bilayers (black lipid membranes). Macroscopic conductivity measurements indicated a voltage-dependent action of nisin. The potential must have a trans-negative orientation with respect to the addition of nisin (added to the cis-side) and a sufficient magnitude (ca. -100 mV). With intact cells the threshold potential was lower (-50 to -80 mV at pH 7.5 and below -50 mV at pH 5.5). Single channel recordings resolved transient multistate pores, strongly resembling those introduced by melittin into artificial bilayers. The pores had diameters in the range of 0.2–1 nm, and lifetimes of few to several hundred milliseconds. The results indicate that nisin has to be regarded as a membrane-depolarizing agent which acts in a voltage-dependent fashion.Abbreviations BLM
Black lipid membranes
- CCCP
carbonyl cyanide m-chlorophenylhydrazone
- DOPC
dioleoyl phosphatidylcholine
- PS
phosphatidylserine
- TPP+
tetraphenylphosphonium cation |
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Keywords: | Nisin mode of action Peptide antibiotics Membrane depolarization Planar lipid bilayers (black lipid membranesgif" alt="ldquo" align="MIDDLE" BORDER="0">black lipid membranes)" target="_blank">gif" alt="rdquo" align="MIDDLE" BORDER="0">) Multi-state pores |
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