Role of Unsaturated Lipid and Ergosterol in Ethanol Tolerance of Model Yeast Biomembranes
We present a combined atomic force microscopy and fluorescence microscopy study of the behavior of a ternary supported lipid bilayer system containing a saturated lipid (DPPC), an unsaturated lipid (DOPC), and ergosterol in the presence of high ethanol (20 vol %). We find that the fluorescent probe...
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Published in | Biophysical journal Vol. 102; no. 3; pp. 507 - 516 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
United States
Elsevier Inc
08.02.2012
Biophysical Society The Biophysical Society |
Subjects | |
Online Access | Get full text |
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Summary: | We present a combined atomic force microscopy and fluorescence microscopy study of the behavior of a ternary supported lipid bilayer system containing a saturated lipid (DPPC), an unsaturated lipid (DOPC), and ergosterol in the presence of high ethanol (20 vol %). We find that the fluorescent probe Texas Red DHPE preferentially partitions into the ethanol-induced interdigitated phase, which allows the use of fluorescence imaging to investigate the phase behavior of the system. Atomic force microscopy and fluorescence images of samples with the same lipid mixture show good agreement in sample morphology and area fractions of the observed phases. Using area fractions obtained from fluorescence images over a broad range of compositions, we constructed a phase diagram of the DPPC/DOPC/ergosterol system at 20 vol % ethanol. The phase diagram clearly shows that increasing unsaturated lipid and/or ergosterol protects the membrane by preventing the formation of the interdigitated phase. This result supports the hypothesis that yeast cells increase ergosterol and unsaturated lipid content to prevent interdigitation and maintain an optimal membrane thickness as ethanol concentration increases during anaerobic fermentations. Changes in plasma membrane composition provide an important survival factor for yeast cells to deter ethanol toxicity. |
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Bibliography: | http://dx.doi.org/10.1016/j.bpj.2011.12.038 ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 |
ISSN: | 0006-3495 1542-0086 |
DOI: | 10.1016/j.bpj.2011.12.038 |