Single-Molecule Investigation of the Influence Played by Lipid Rafts on Ion Transport and Dynamic Features of the Pore-Forming Alamethicin Oligomer

Single-Molecule Investigation of the Influence Played by Lipid Rafts on Ion Transport and Dynamic... In this experimental work we employed single-molecule electrical recordings on alamethicin oligomers inserted in lipid bilayers made of brain sphingomyelin (bSM), palmitoyloleoylphosphatidylcholine (POPC) and cholesterol (chol) to unravel novel aspects regarding lipid raft interactions with pore-forming peptides. We probed the effect of lipid rafts on electrical properties of inserted alamethicin oligomers, and our data convincingly prove that the single-channel electrical conductance of various subconductance states of the alamethicin oligomer (1) increases in the presence of raft-containing ternary lipid mixtures (POPC–chol–bSM) compared to cases when bilayers were made of POPC–chol and POPC and (2) decreases in the presence of raft-containing ternary lipid mixtures compared to nonraft ternary mixtures which favor the fluid and liquid ordered phases alone. Our data demonstrate that the presence of lipid rafts leads to a slower association kinetics of alamethicin oligomers, seemingly reflecting a slower lateral diffusion process of such peptide aggregates compared to the case of nonraft, binary lipid mixtures. Furthermore, we show that the electrical capacitance of ternary lipid mixtures (POPC–chol–bSM) decreases in the presence of raft domains by comparison to nonraft binary phases (POPC–chol) or POPC alone, and this could constitute an additional mechanism via which macroscopic electrical manifestations of eukaryotic cells are modulated by the coexistence of gel and fluid domains of the plasma membrane. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Single-Molecule Investigation of the Influence Played by Lipid Rafts on Ion Transport and Dynamic Features of the Pore-Forming Alamethicin Oligomer

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Publisher
Springer-Verlag
Copyright
Copyright © 2008 by Springer Science+Business Media, LLC
Subject
Life Sciences; Human Physiology ; Biochemistry, general
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-008-9131-7
Publisher site
See Article on Publisher Site

Abstract

In this experimental work we employed single-molecule electrical recordings on alamethicin oligomers inserted in lipid bilayers made of brain sphingomyelin (bSM), palmitoyloleoylphosphatidylcholine (POPC) and cholesterol (chol) to unravel novel aspects regarding lipid raft interactions with pore-forming peptides. We probed the effect of lipid rafts on electrical properties of inserted alamethicin oligomers, and our data convincingly prove that the single-channel electrical conductance of various subconductance states of the alamethicin oligomer (1) increases in the presence of raft-containing ternary lipid mixtures (POPC–chol–bSM) compared to cases when bilayers were made of POPC–chol and POPC and (2) decreases in the presence of raft-containing ternary lipid mixtures compared to nonraft ternary mixtures which favor the fluid and liquid ordered phases alone. Our data demonstrate that the presence of lipid rafts leads to a slower association kinetics of alamethicin oligomers, seemingly reflecting a slower lateral diffusion process of such peptide aggregates compared to the case of nonraft, binary lipid mixtures. Furthermore, we show that the electrical capacitance of ternary lipid mixtures (POPC–chol–bSM) decreases in the presence of raft domains by comparison to nonraft binary phases (POPC–chol) or POPC alone, and this could constitute an additional mechanism via which macroscopic electrical manifestations of eukaryotic cells are modulated by the coexistence of gel and fluid domains of the plasma membrane.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Oct 11, 2008

References

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