Targeted Modification of Membrane Lipids

膜脂质的靶向修饰 项目摘要 膜的脂质组成在生物学中具有重要的分支。众所周知， 细菌和哺乳动物细胞在其膜中含有不同的脂质组。而哺乳动物细胞 膜主要由两性离子脂质组成，细菌细胞通常在大的膜中显示阴离子脂质。 是介于利用这种差异，许多生物进化出阳离子宿主防御肽 （HDPs），其充当先天免疫的前线以抵御入侵的细菌病原体。为 例如，人嗜中性粒细胞依赖于阳离子防御素来杀死和清除细菌细胞。收购 为了抵抗阳离子HDPs，选择的细菌物种合成脂质Lys-PG，其携带一个网， 正电荷我们假设，结合Lys-PG并因此掩盖其网络的合成分子 电荷将使细菌细胞对HDP的杀伤重新敏感。为了验证这一假设，我们将开发合成 Lys-PG的修饰剂，通过引入可逆的共价弹头到结构良好的支架。此外，我们将 在体外和小鼠感染模型中测试Lys-PG修饰的功效。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。 计算建模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Lys-PG的有效和特异性修饰剂。这部分 该提案的一部分将基于我们小组最近开发的强大的肽双环化策略; 3） 将测试在1）和2）中开发的Lys-PG改性剂增强杀菌性的能力， 几种HDPs和中性粒细胞的活性。它们促进细菌清除的功效将进一步研究 在感染的小鼠模型中。如果成功，拟议的工作将产生一个新的战略，以打击 细菌病原体的耐药性菌株。虽然拟议的工作重点是Lys-PG， 这里开发的方法应该可以扩展到其他具有生物学意义的脂质修饰。

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.