Ergosterol is mainly located in the cytoplasmic leaflet of the yeast plasma membrane.

Autor: Solanko LM; Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark., Sullivan DP; Department of Biochemistry, Weill Cornell Medical College, New York, New York., Sere YY; Department of Biochemistry, Weill Cornell Medical College, New York, New York., Szomek M; Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark., Lunding A; Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark., Solanko KA; Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark., Pizovic A; Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark., Stanchev LD; Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark.; Department of Molecular Biochemistry, Ruhr-University Bochum, Bochum, Germany., Pomorski TG; Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark.; Department of Molecular Biochemistry, Ruhr-University Bochum, Bochum, Germany., Menon AK; Department of Biochemistry, Weill Cornell Medical College, New York, New York., Wüstner D; Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark.
Jazyk: angličtina
Zdroj: Traffic (Copenhagen, Denmark) [Traffic] 2018 Mar; Vol. 19 (3), pp. 198-214.
DOI: 10.1111/tra.12545
Abstrakt: Transbilayer lipid asymmetry is a fundamental characteristic of the eukaryotic cell plasma membrane (PM). While PM phospholipid asymmetry is well documented, the transbilayer distribution of PM sterols such as mammalian cholesterol and yeast ergosterol is not reliably known. We now report that sterols are asymmetrically distributed across the yeast PM, with the majority (~80%) located in the cytoplasmic leaflet. By exploiting the sterol-auxotrophic hem1Δ yeast strain we obtained cells in which endogenous ergosterol was quantitatively replaced with dehydroergosterol (DHE), a closely related fluorescent sterol that functionally and accurately substitutes for ergosterol in vivo. Using fluorescence spectrophotometry and microscopy we found that <20% of DHE fluorescence was quenched when the DHE-containing cells were exposed to membrane-impermeant collisional quenchers (spin-labeled phosphatidylcholine and trinitrobenzene sulfonic acid). Efficient quenching was seen only after the cells were disrupted by glass-bead lysis or repeated freeze-thaw to allow quenchers access to the cell interior. The extent of quenching was unaffected by treatments that deplete cellular ATP levels, collapse the PM electrochemical gradient or affect the actin cytoskeleton. However, alterations in PM phospholipid asymmetry in cells lacking phospholipid flippases resulted in a more symmetric transbilayer distribution of sterol. Similarly, an increase in the quenchable pool of DHE was observed when PM sphingolipid levels were reduced by treating cells with myriocin. We deduce that sterols comprise up to ~45% of all inner leaflet lipids in the PM, a result that necessitates revision of current models of the architecture of the PM lipid bilayer.
(© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)
Databáze: MEDLINE
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