Mechanistic role of ergosterol in membrane rigidity and cycloheximide resistance in Saccharomyces cerevisiae
Mechanistic role of ergosterol in membrane rigidity and cycloheximide resistance in Saccharomyces cerevisiae
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DOI：
10.1016/j.bbamem.2008.12.002
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发表时间：
2009-03-01
影响因子：
3.4
通讯作者：
Hiraki, Toshiki
中科院分区：
文献类型：
--
作者：
Abe, Fumiyoshi;Hiraki, Toshiki
在麦角甾醇生物合成后期缺陷的酿酒酵母突变体是有活力的，但在质膜内积累结构改变的甾醇。尽管多效性异常在erg突变体中具有重要意义，但人们对甾醇改变如何机械地影响膜结构以及与个体突变表型的相关性知之甚少。在这里，我们证明了膜的顺序和空隙的发生是膜刚性和对药物过敏的决定因素。在5个erg Delta突变体中，erg2 Delta突变体对环己亚胺的敏感性最为显著。值得注意的是，时间分辨各向异性的测量表明，erg2 δ突变降低了膜序参数(S)，并显著提高了1-[4-（三甲氨基）苯]-6-苯基-1,3,5-己三烯（TMA-DPH）在质膜中的旋转扩散系数（D-w），增加了8倍，这证明了麦角甾醇对膜完整性的要求。在这些菌株中，环己亚胺的IC50与S/D-w密切相关，表明膜紊乱和质膜内空隙的增加协同促进了环己亚胺在膜上的被动扩散。外源性麦角甾醇部分恢复了upc2-1erg2 δ菌株的膜特性。在这项研究中，我们描述了麦角甾醇调节质膜动态特性的能力，并考虑了药物通透性的相关性。(C) 2008 Elsevier B.V.版权所有
Mutants of Saccharomyces cerevisiae defective in the late steps of ergosterol biosynthesis are viable but accumulate structurally altered sterols within the plasma membrane. Despite the significance of pleiotropic abnormalities in the erg mutants, little is known about how sterol alterations mechanically affect the membrane structure and correlate with individual mutant phenotypes. Here we demonstrate that the membrane order and occurrence of voids are determinants of membrane rigidity and hypersensitivity to a drug. Among five erg Delta mutants, the erg2 Delta mutant exhibited the most marked sensitivity to cycloheximide. Notably, measurement of time-resolved anisotropy indicated that the erg2 Delta mutation decreased the membrane order parameter (S), and dramatically increased the rotational diffusion coefficient (D-w) of 1-[4-(trimethylamino)pheny]-6-phenyl-1,3,5-hexatriene (TMA-DPH) in the plasma membrane by 8-fold, providing evidence for the requirement of ergosterol for membrane integrity. The IC50 of cycloheximide was closely correlated with S/D-w in these strains, suggesting that the membrane disorder and increasing occurrence of voids within the plasma membrane synergistically enhance passive diffusion of cycloheximide across the membrane. Exogenous ergosterol partially restored the membrane properties in the upc2-1erg2 Delta strain. In this study, we describe the ability of ergosterol to adjust the dynamic properties of the plasma membrane, and consider the relevance of drug permeability. (C) 2008 Elsevier B.V. All rights reserved.