PDF(Pubmed)
Abstract：
Natamycin is an antifungal polyene macrolide that is used as a food preservative but also to treat fungal keratitis and other yeast infections. In contrast to other polyene antimycotics, natamycin does not form ion pores in the plasma membrane, but its mode of action is poorly understood. Using nuclear magnetic resonance (NMR) spectroscopy of deuterated sterols, we find that natamycin slows the mobility of ergosterol and cholesterol in liquid-ordered (Lo) membranes to a similar extent. This is supported by molecular dynamics (MD) simulations, which additionally reveal a strong impact of natamycin dimers on sterol dynamics and water permeability. Interference with sterol-dependent lipid packing is also reflected in a natamycin-mediated increase in membrane accessibility for dithionite, particularly in bilayers containing ergosterol. NMR experiments with deuterated sphingomyelin (SM) in sterol-containing membranes reveal that natamycin reduces phase separation and increases lipid exchange in bilayers with ergosterol. In ternary lipid mixtures containing monounsaturated phosphatidylcholine, saturated SM, and either ergosterol or cholesterol, natamycin interferes with phase separation into Lo and liquid-disordered (Ld) domains, as shown by NMR spectroscopy. Employing the intrinsic fluorescence of natamycin in ultraviolet-sensitive microscopy, we can visualize the binding of natamycin to giant unilamellar vesicles (GUVs) and find that it has the highest affinity for the Lo phase in GUVs containing ergosterol. Our results suggest that natamycin specifically interacts with the sterol-induced ordered phase, in which it disrupts lipid packing and increases solvent accessibility. This property is particularly pronounced in ergosterol containing membranes, which could underlie the selective antifungal activity of natamycin.
摘要：
纳他霉素是一种抗真菌多烯大环内酯，用作食品防腐剂，但也用于治疗真菌性角膜炎和其他酵母菌感染。与其他多烯抗真菌剂相比，纳他霉素不会在质膜中形成离子孔，但是人们对它的作用方式知之甚少。使用氘代固醇的核磁共振（NMR）光谱，我们发现纳他霉素在液体有序（Lo）膜中减缓麦角甾醇和胆固醇的迁移率。这得到了分子动力学（MD）模拟的支持，这也揭示了纳他霉素二聚体对甾醇动力学和水渗透性的强烈影响。对固醇依赖性脂质包装的干扰也反映在钠霉素介导的连二亚硫酸盐膜可及性增加中，特别是在含有麦角固醇的双层中。在含固醇的膜中使用氘代鞘磷脂（SM）进行的NMR实验表明，纳他霉素减少了与麦角甾醇的双层中的相分离并增加了脂质交换。在含有单不饱和磷脂酰胆碱的三元脂质混合物中，饱和SM,麦角固醇或胆固醇，纳他霉素干扰相分离为Lo和液体无序（Ld）域，如NMR光谱所示。在紫外敏感显微镜中利用纳他霉素的固有荧光，我们可以可视化游霉素与巨大的单层囊泡（GUV）的结合，并发现它对含有麦角固醇的GUV中的Lo相具有最高的亲和力。我们的结果表明，纳他霉素与固醇诱导的有序相特异性相互作用，其中它破坏脂质包装并增加溶剂可及性。这种性质在含有麦角甾醇的膜中特别明显，这可能是纳他霉素选择性抗真菌活性的基础。
