Pure lipid vesicles can induce channel-like conductances in planar bilayers

Woodbury, Dixon J.

doi:10.1007/bf01870853

Cited by 37 publications

(21 citation statements)

References 10 publications

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“…The resulting small and transient openings suffice for the diffusion of smaller molecules, including the peptides themselves in and out of the cell interior [50] and can explain the step-wise changes in conductivity that have been monitored for magainin 2 or for cecropins [45][46][47]. Interestingly, similar conductivity increases have also been observed in the presence of detergents [61,62], in pure lipid membranes [63][64][65], or when small unilamellar phospholipid vesicles are added to planar lipid bilayers [66].…”

Section: Description Of the Complexity Of Peptide-lipid Interactions mentioning

confidence: 78%

Rationalizing the membrane interactions of cationic amphipathic antimicrobial peptides by their molecular shape

Bechinger

2009

Current Opinion in Colloid & Interface Science

106

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Section: Description Of the Complexity Of Peptide-lipid Interactions mentioning

confidence: 78%

Rationalizing the membrane interactions of cationic amphipathic antimicrobial peptides by their molecular shape

Bechinger

2009

Current Opinion in Colloid & Interface Science

106

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“…On the other hand the detailed characteristics of "single-channel" measurements (14,24,25) as well as energetic considerations (23) seem to indicate that the detergent-like properties of amphipathic peptides provide a more probable explanation for the rare observation of the stepwise increase in conductivity. Whereas the electrophysiological properties of amphipathic helical peptides are significantly different from those of "classical hydrophobic channel peptides" such as alamethicin (23,27), they resemble those observed in the presence of detergents (51)(52)(53), pure lipid membranes (54 -56), or small unilamellar phospholipid vesicles when added to planar lipid bilayers (57). The conductivity increases measured in the presence of detergents or magainin antibiotic peptides vary over several orders of magnitude, show large variations also within each conductance level, and exhibit a low degree of ion selectivity.…”

Section: Discussionmentioning

confidence: 97%

The Interactions of Histidine-containing Amphipathic Helical Peptide Antibiotics with Lipid Bilayers

Vogt

Bechinger

1999

Journal of Biological Chemistry

170

197

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The ␣-helix of the designed amphipathic peptide antibiotic LAH 4 (KKALLALALHHLAHLALHLALALKKA-NH 2 ) strongly interacts with phospholipid membranes. The peptide is oriented parallel to the membrane surface under acidic conditions, but transmembrane at physiological pH (Bechinger, B. (1996) J. Mol. Biol. 263, 768 -775). LAH 4 exhibits antibiotic activities against Escherichia coli and Bacillus subtilis; the peptide does not, however, lyse human red blood cells at bacteriocidal concentrations. The antibiotic activities of LAH 4 are 2 orders of magnitude more pronounced at pH 5 when compared with pH 7.5. Although peptide association at low pH is reduced when compared with pH 7.5, the release of the fluorophore calcein from large unilamellar 1-palmitoyl-2-oleoyl-sn-glycerol-3-phosphocholine or 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol vesicles is more pronounced at pH values where LAH 4 adopts an orientation along the membrane surface. The calcein release experiments thereby parallel the results obtained in antibiotic assays. Despite a much higher degree of association, calcein release activity of LAH 4 is significantly decreased for negatively charged membranes. Pronounced differences in the interactions of LAH 4 with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol or 1-palmitoyl-2-oleoyl-sn-glycerol-3-phosphocholine membranes also become apparent when the mechanisms of dye release are investigated. The results presented in this paper support models in which antibiotic activity is caused by detergent-like membrane destabilization, rather than pore formation by helical peptides in transmembrane alignments.As pathogenic bacteria and fungi turn resistant against many commonly used antibiotics, considerable efforts are undertaken to develop novel ways to fight infections. Host defensive polypeptides are an integral part of the innate immune system and have been discovered in a wide variety of species, including insects, vertebrates, and humans (1). Some of these peptides are stored in intracellular compartments and their release allows for an immediate response when infections occur. Amphipathic peptides exhibit a strong activity against a wide range of bacteria, fungi, and viruses (2). Examples include the naturally occurring linear polypeptides PGLa (2, 3), magainins (4, 5), cecropins (6), and defensins (7,8), as well as derivatives thereof (5, 9 -11). More recently interest in these peptides has further increased when their tumoricidal activity was demonstrated (12-16).Linear peptide antibiotics, such as magainins and cecropins, are thought to express their biological activity by related mechanisms (17). Although they show no primary sequence homology, they are all positively charged and form amphipathic ␣-helices in the presence of lipid membranes. Experimental evidence suggests that direct peptide-lipid interactions are important for the expression of antibiotic activity of these substances (18), rather than specific association with a chiral receptor. In particular, the first recognition and membrane ass...

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“…Channellike activity has been reported to occur in lipid bilayers containing pure lipid vesicles. [30][31][32] The possibility of the presence of such events needs to be studied further.…”

Section: Effects Of Lysophospholipids On Ikatpmentioning

confidence: 99%

Regulation of K+ channels in cardiac myocytes by free fatty acids.

Kim

Duff

1990

Circulation Research

107

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Using rat ventricular cells, we studied the actions of free fatty acids and their ability to modulate the ATP-sensitive K+ channel and to activate a new type of ATP-insensitive K+ channel previously identified in rat atrial cells. Perfusion of the cytoplasmic face of the membrane with unsaturated fatty acids (10-50 microM) such as arachidonic, linoleic, and eicosatrienoic acids inhibited the ATP-sensitive K+ channel almost completely; lysophospholipids also markedly inhibited this channel. Inhibition was due to decreases in the frequency and the burst duration of channel openings. Arachidonic acid activated the ATP-insensitive K+ channel with an outwardly rectifying property. Since the level of free fatty acids rises after longer periods of ischemia, we speculate that the ATP-insensitive K+ channel contributes to the late or secondary phase of extracellular K+ accumulation.

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Pure lipid vesicles can induce channel-like conductances in planar bilayers

Cited by 37 publications

References 10 publications

Rationalizing the membrane interactions of cationic amphipathic antimicrobial peptides by their molecular shape

Rationalizing the membrane interactions of cationic amphipathic antimicrobial peptides by their molecular shape

The Interactions of Histidine-containing Amphipathic Helical Peptide Antibiotics with Lipid Bilayers

Regulation of K+ channels in cardiac myocytes by free fatty acids.

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