Wang M M, Sugar I P, Chong P L
Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA.
Biochemistry. 1998 Aug 25;37(34):11797-805. doi: 10.1021/bi980290k.
Nystatin isolated from Streptomyces is a polyene antibiotic that is frequently used in the treatment and prophylaxis of fungal infections. Here, the fractional sterol concentration dependencies of the partition coefficient for partitioning of nystatin into ergosterol/dimyristoyl-L-alpha-phosphatidylcholine (DMPC), cholesterol/DMPC, ergosterol/1-palmitoyl-2-oleoyl-L-alpha-phosphatidylcholine (POPC), and ergosterol/POPC/1-palmitoyl-2-oleoyl-L-alpha-phosphatidylethano lam ine (POPE) multilamellar vesicles have been determined fluorometrically at 37 degrees C using approximately 0.3-1.0 mol % sterol concentration increments over a wide concentration range (e.g., 18-54 mol % sterol). This unconventional approach of varying membrane sterol content, in contrast to previous studies using large sterol concentration increments (e.g., 10 mol %), leads to a striking observation. The partition coefficient of nystatin changes dramatically with membrane sterol content in a well-defined alternating manner, displaying a local minimum at or very close to the critical sterol mole fractions (e.g., 20.0, 22.2, 25.0, 33.3, 40.0, and 50.0 mol % sterol) predicted for sterols regularly distributed in either hexagonal or centered rectangular superlattices. In ergosterol/DMPC bilayers, for example, there is a >3-fold increase in nystatin partitioning with a minute change (approximately 1 mol %) in sterol content on either side of the critical sterol mole fraction, 25.0 mol %. These results provide semifunctional evidence supporting the sterol regular distribution model [Chong, P. L.-G. (1994) Proc. Natl. Acad. Sci. U.S.A. 91, 10069-10073]. More importantly, these results reveal a new membrane phenomenon, that is, that nystatin partitioning is affected by the extent of sterol regular distribution in the plane of the membrane. This phenomenon occurs not only in saturated (e.g., DMPC) but also in unsaturated (e.g., POPC) lipid membranes, and persists in the presence of polar headgroup heterogeneity (e.g., POPC/POPE). This membrane property points to a new method for studying the interactions of polyene antibiotics with sterol-containing membranes, and the need to consider the membrane sterol content of the target cells when administering nystatin or other polyene antibiotics.
从链霉菌中分离出的制霉菌素是一种多烯抗生素，常用于治疗和预防真菌感染。在此，使用荧光法在37℃下，以约0.3 - 1.0摩尔%的甾醇浓度增量，在较宽的浓度范围（例如18 - 54摩尔%甾醇）内，测定了制霉菌素分配到麦角甾醇/二肉豆蔻酰-L-α-磷脂酰胆碱（DMPC）、胆固醇/DMPC、麦角甾醇/1-棕榈酰-2-油酰-L-α-磷脂酰胆碱（POPC）和麦角甾醇/POPC/1-棕榈酰-2-油酰-L-α-磷脂酰乙醇胺（POPE）多层囊泡中的分配系数对甾醇浓度分数的依赖性。与以往使用大的甾醇浓度增量（例如10摩尔%）的研究相比，这种改变膜甾醇含量的非常规方法导致了一个惊人的发现。制霉菌素的分配系数随膜甾醇含量以明确的交替方式显著变化，在预测的以六方或中心矩形超晶格规则分布的甾醇的临界甾醇摩尔分数（例如20.0、22.2、25.0、33.3、40.0和50.0摩尔%甾醇）处或非常接近该分数处显示出局部最小值。例如，在麦角甾醇/DMPC双层膜中，在临界甾醇摩尔分数25.0摩尔%两侧，甾醇含量有微小变化（约1摩尔%）时，制霉菌素的分配增加了3倍以上。这些结果提供了半功能性证据支持甾醇规则分布模型[Chong, P. L.-G. (1994) Proc. Natl. Acad. Sci. U.S.A. 91, 10069 - 10073]。更重要的是，这些结果揭示了一种新的膜现象，即制霉菌素的分配受膜平面中甾醇规则分布程度的影响。这种现象不仅发生在饱和（例如DMPC）脂质膜中，也发生在不饱和（例如POPC）脂质膜中，并且在存在极性头基异质性（例如POPC/POPE）的情况下仍然存在。这种膜特性指出了一种研究多烯抗生素与含甾醇膜相互作用的新方法，以及在施用制霉菌素或其他多烯抗生素时需要考虑靶细胞的膜甾醇含量。
