期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2014
卷号：111
期号：38
页码：13864-13869
DOI：10.1073/pnas.1409011111
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceGiven the extensive use of lipid bilayer reconstitution for the study of mechanosensitive channels, it is imperative to understand the biophysical properties of lipid bilayers. We have theoretically and experimentally proven that the traditional micropipette aspiration method fails to accurately describe these properties. Herein we introduce a superior framework, which combines computational modeling with patch fluorometry for the assessment of bilayer properties. Our results show the limitations of Laplace's law for estimation of tension within a patch membrane. We also demonstrate, in contrast to the cell-attached configuration, there is a significant difference between the stress developed in the outer and in the inner monolayers of the bilayer in the excised patch configuration. These results are of critical importance for patch-clamp electrophysiology in general. The lipid bilayer plays a crucial role in gating of mechanosensitive (MS) channels. Hence it is imperative to elucidate the rheological properties of lipid membranes. Herein we introduce a framework to characterize the mechanical properties of lipid bilayers by combining micropipette aspiration (MA) with theoretical modeling. Our results reveal that excised liposome patch fluorometry is superior to traditional cell-attached MA for measuring the intrinsic mechanical properties of lipid bilayers. The computational results also indicate that unlike the uniform bilayer tension estimated by Laplace's law, bilayer tension is not uniform across the membrane patch area. Instead, the highest tension is seen at the apex of the patch and the lowest tension is encountered near the pipette wall. More importantly, there is only a negligible difference between the stress profiles of the outer and inner monolayers in the cell-attached configuration, whereas a substantial difference ([~]30%) is observed in the excised configuration. Our results have far-reaching consequences for the biophysical studies of MS channels and ion channels in general, using the patch-clamp technique, and begin to unravel the difference in activity seen between MS channels in different experimental paradigms.
关键词：MscL ; azolectin ; electrophysiology ; finite element modeling
