PEPTIDE ANTIBIOTICS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 Mainin是一种多肽抗生素，直接与靶细胞中的脂膜相互作用。Mainin和相关多肽的作用方式是在膜上形成大的非选择性孔，导致细胞溶解。许多方法，如圆二色谱、固体核磁共振、拉曼散射、中子散射等都被用来推断这种作用模式。然而，这些方法都没有直接可视化单个孔隙的结构，当前的模型存在一些令人费解的不一致之处。在这里，我们提出了一种研究肽/脂相互作用的新方法，该方法使用冷冻-EM来成像Mainin诱导的磷脂囊泡中的毛孔。由于假设的孔的大小对于直接观察单个孔来说是相当小的，我们也在散布的情况下分析低温电磁数据。也就是说，通过分析选定囊泡的功率谱来执行“虚拟”电子散射实验。虽然我们希望直接对单个毛孔进行成像，但作为第一步，这将允许在批量样品中观察Mainin的效果，并将CryoEM结果与之前的X射线和中子散射实验相关联。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Magainin is a peptide antibiotic that interacts directly with the lipid membrane in the target cell. The mode of action for magainin and related peptides is formation of large nonselective pores in the membrane leading to cell lysis. A number of methods, like Circular Dichroism, Solid State NMR, Raman Scattering, Neutron Scattering, etc., have been used to infer this mode of action. However, none of those methods has directly visualized the structure of an individual pore, and some puzzling inconsistencies exist in the current models. Here we present a new method for studying peptide/lipid interactions, which employs Cryo-EM to image Magainin-induced pores in phospholipid vesicles. Since the size of the putative pores is quite small for direct observation of individual pores, we are also analyzing the cryo-EM data in a scattering context. That is, performing 'virtual' electron scattering experiments through analysis of the power spectra of selected vesicles. While we hope to directly image individual pores, as a first step this permits observation of the effects of Magainin in bulk specimens, and relating the cryoEM results to previous X-ray and neutron scattering experiments.