Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada; Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
Biochim Biophys Acta Biomembr. 2019 Apr 1;1861(4):738-747. doi: 10.1016/j.bbamem.2019.01.003. Epub 2019 Jan 10.
The cyclic lipopeptide fengycin, produced by Bacillus subtilis, exhibits its antimicrobial capabilities by altering the integrity of the cell membrane of plant pathogens. Previous work has correlated fengycin activity with membrane characteristics, such as sterol content. This work focused on the influence of fengycin on supported lipid bilayers containing varying levels of ergosterol. Total internal reflection fluorescence (TIRF) microscopy was used to visualize and distinguish ordered (L/L) and disordered (L/L) domains in the model membranes following exposure to low (50 μg) and high (500 μg) fengycin doses. Application of an initial low dose of fengycin to 0% and 3% ergosterol-containing bilayers resulted in redistribution of L/L and L/L domains, respectively, which the bilayers compensated and corrected for over time. These membranes were unable to tolerate a second 50 μg dose or a single high fengycin dose. The 6% ergosterol bilayers were able to tolerate sequential low doses of fengycin. Exposure of these bilayers to the high fengycin dose caused a decrease in the number of L domains, albeit less than that seen in the 0% and 3% ergosterol bilayers. Bilayers containing 12% ergosterol, exhibited the least amount of change after fengycin exposure. These were the only bilayer to exhibit an increase in area taken up by ordered domains. These results suggest fengycin may preferentially act on the L or L phase, the area in which ergosterol resides. Bilayers containing low levels of ergosterol appear to be more sensitive to the lipopeptide, suggesting ergosterol plays a role in buffering perturbations caused by fengycin.
由枯草芽孢杆菌产生的环状脂肽丰余菌素通过改变植物病原体细胞膜的完整性来发挥其抗菌能力。先前的工作已经将丰余菌素的活性与膜特性相关联，例如固醇含量。本工作集中研究了丰余菌素对含有不同水平麦角固醇的支撑脂质双层的影响。总内反射荧光（TIRF）显微镜用于可视化和区分暴露于低（50μg）和高（500μg）丰余菌素剂量后的模型膜中的有序（L/L）和无序（L/L）域。在 0%和 3%麦角固醇含量的双层中应用初始低剂量的丰余菌素分别导致 L/L 和 L/L 域的重新分布，随着时间的推移，双层会对此进行补偿和纠正。这些膜无法耐受第二低剂量的 50μg 丰余菌素或单一高剂量的丰余菌素。6%麦角固醇双层能够耐受连续的低剂量丰余菌素。暴露于高丰余菌素剂量会导致 L 域数量减少，尽管少于在 0%和 3%麦角固醇双层中观察到的数量。暴露于丰余菌素后，含有 12%麦角固醇的双层变化最小。这些是唯一表现出有序域占据面积增加的双层。这些结果表明丰余菌素可能优先作用于 L 或 L 相，即麦角固醇所在的区域。含有低水平麦角固醇的双层似乎对脂肽更为敏感，这表明麦角固醇在缓冲丰余菌素引起的扰动方面发挥作用。
