Targeted Modification of Membrane Lipids

膜脂的靶向修饰 项目摘要 膜的脂类成分在生物学上有重要的影响。很早以前就知道 细菌和哺乳动物细胞的细胞膜中含有一组不同的脂类。而哺乳动物细胞 膜主要由两性离子类脂组成，细菌细胞通常表现为大量的阴离子类脂 数量。利用这种差异，许多生物进化出了阳离子宿主防御肽。 (HDPs)，作为先天免疫的前线，抵御入侵的细菌病原体。为 例如，人类中性粒细胞依靠阳离子防御素来杀灭和清除细菌细胞。收购 对阳离子HDPs的抗性，选定的细菌物种合成携带网的脂类Lys-PG 带正电荷。我们假设与Lys-PG结合并因此掩盖其网络的合成分子 电荷会使细菌细胞对高密度脂蛋白的杀灭重新敏感。为了检验这一假设，我们将开发一种合成的 通过在结构良好的支架中引入可逆的共价弹头来修饰Lys-PG。我们会走得更远 在体外和小鼠感染模型中检测Lys-PG修饰的效果。具体目标是：1)我们将 使用已知的可折叠环肽支架组装多个侧链用于Lys-PG修饰。 计算模型将与实验表征相结合，以优化Lys-PG结合；2) 我们将通过筛选新的双环肽文库来开发有效和特异的Lys-PG修饰剂。这一部分 将基于我们团队最近开发的强大的多肽自行车策略；3) 将测试在1)和2)中开发的Lys-PG改性剂增强杀菌的能力 几种高密度脂蛋白和中性粒细胞的活性。我们将进一步研究它们促进细菌清除的效果。 在感染的小鼠模型中。如果成功，这项拟议的工作将产生一种新的战略来对抗 细菌病原体的耐药菌株。虽然拟议的工作重点是Lys-PG，但 这里开发的方法学应该可以推广到其他具有生物学意义的脂类修饰。

Targeted Modification of Membrane Lipids Project Summary The lipid composition of membranes has critical ramifications in biology. It has been long known that bacterial and mammalian cells harbor a different set of lipids in their membranes. While a mammalian cell membrane is largely composed of zwitterionic lipids, bacterial cells typically display anionic lipids in large quantities. Taking advantage of this difference, many organisms have evolved cationic host defense peptides (HDPs), which serve as the frontline of the innate immunity to fend off invading bacterial pathogens. For example, human neutrophils rely on cationic defensins for bacterial cell killing and clearance. To acquire resistance against cationic HDPs, selected bacterial species synthesize the lipid Lys-PG, which carries a net positive charge. We hypothesize that synthetic molecules that bind Lys-PG and consequently mask its net charge will re-sensitize the bacterial cells to killing by HDPs. To test the hypothesis, we will develop synthetic modifiers of Lys-PG by introducing reversible covalent warheads into well-structured scaffolds. Further we will test the efficacy of Lys-PG modification in vitro and in mouse infection models. The specific aims are: 1) we will use a known, foldable cyclic peptide scaffold to assemble multiple side chains for Lys-PG modification. Computational modeling will be integrated with experimental characterization to optimize for Lys-PG binding; 2) we will develop potent and specific modifiers of Lys-PG by screening novel bicyclic peptide libraries. This part of the proposal will be based on a powerful peptide bicyclization strategy recently developed by our group; 3) the Lys-PG modifiers developed in 1) and 2) will be tested for their capability to potentiate the bactericidal activity of several HDPs and neutrophils. Their efficacy to facilitate bacterial clearance will be further examined in mouse models of infection. With success, the proposed work will yield a novel strategy to fight against the drug-resistance strains of bacterial pathogens. Although the proposed work focuses on Lys-PG, the methodology developed here should be extendable to other lipid modifications of biological significance.