Latoud C, Peypoux F, Michel G
Laboratoire de Biochimie Microbienne, Université de Lyon I, Villeurbanne, France.
Can J Microbiol. 1990 Jun;36(6):384-9. doi: 10.1139/m90-067.
The binding of the membrane-active lipopeptide antibiotic iturin A to yeast cells was studied using radioactive iturin A. Saccharomyces cerevisiae had a maximum binding capacity of 5.6 x 10(9) molecules per single cell. The Scatchard plot of binding showed a biphasic profile, with a lower dissociation constant for small concentrations of iturin A. The break of slope at 30 microM iturin A corresponds to the micellization of antibiotic in solution. The binding is also dependent on the nature of the sterol present in the membrane. A mutant yeast strain with a membrane containing cholesterol instead of ergosterol showed the highest affinity for iturin A and the highest sensitivity to this antibiotic, as measured by K+ ion release. In contrast the presence of stigmasterol increased the resistance of the cells to iturin A.
使用放射性伊枯草菌素A研究了膜活性脂肽抗生素伊枯草菌素A与酵母细胞的结合。酿酒酵母的最大结合能力为每单个细胞5.6×10⁹个分子。结合的Scatchard图显示出双相特征，对于低浓度的伊枯草菌素A具有较低的解离常数。在30微摩尔伊枯草菌素A处斜率的变化对应于溶液中抗生素的胶束化。结合还取决于膜中存在的甾醇的性质。通过K⁺离子释放测量，一种膜中含有胆固醇而非麦角固醇的突变酵母菌株对伊枯草菌素A表现出最高的亲和力和对该抗生素的最高敏感性。相反，豆甾醇的存在增加了细胞对伊枯草菌素A的抗性。
