PEPTIDE ANTIBIOTICS

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 爪蟾抗菌肽是一种肽类抗生素，可直接与靶细胞的脂质膜相互作用。爪蟾抗菌肽和相关肽的普遍作用模式是在膜中形成大的非选择性孔，导致细胞溶解。许多方法，如圆二色性、固态NMR、拉曼散射、中子散射等，已经被用来推断这种行为模式。然而，这些方法都没有直接观察到单个孔隙的结构，并且目前的模型中存在一些令人困惑的不一致性。在这里，我们提出了一种新的方法来研究肽/脂质的相互作用，采用冷冻EM成像爪蟾抗菌肽诱导的磷脂囊泡孔。由于推定的孔隙的大小是相当小的直接可视化的个别孔隙，我们也在散射的背景下分析cryo-EM数据。也就是说，通过分析选定的囊泡的功率谱来进行“虚拟”电子散射实验。虽然我们希望直接对单个孔隙进行成像，但作为第一步，这允许观察Magainin在散装样品中的影响，并将cryoEM结果与先前的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 prevalent 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 observed 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 visualization 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 specimen, and relating the cryoEM results to previous X-ray and neutron scattering experiments.