Biogenesis of surface-exposed lipoproteins in Gram-negative bacteria

项目总结 革兰氏阴性细菌的外膜是一个动态的界面，它调节细菌之间的相互作用 通过在宿主表面显示蛋白质来与宿主结合。新近发现的表面暴露的脂蛋白 (SLP)在铁的获取、黏附、免疫逃避和服务等发病机制中起关键作用。 作为有价值的疫苗靶标。尽管它们在生物医学上很重要，但脂蛋白背后的机制 定位到细胞表面是细菌包膜生物发生过程中最不被理解的方面。长的- 本实验室研究的长期目标是确定脂蛋白靶向的机制，并输出到 细菌细胞表面。我们预计，具有相似拓扑和/或结构的脂蛋白基团 特征共享专用装配路径。提高我们对分子决定因素的理解 将使脂蛋白定位和预测计算模型的开发成为可能 SLP的基因组鉴定。一个SLP亚家族包括依赖于伴侣β的脂蛋白- 用于表面暴露的桶状外膜蛋白(OMP)。我们发现了RCSF脂蛋白在 大肠埃希菌是这种类型的第一个例子。我们进一步发现，高度保守的和 必需的β-Barrel组装机械(BAM)复合体在RCSF的生物发生中起着关键作用， 揭示Bam复合体在脂蛋白生物发生中的新功能。在这里，我们建议使用 结合遗传学、生物化学和质谱学方法来鉴定分子 Bam复合体在细胞表面显示脂蛋白的机制。我们是专门的 对Bam复合体如何识别脂蛋白和协调脂蛋白表面暴露感兴趣 带OMP组件。拟议研究的完成将大大扩大我们的低估 SLP的生物发生和革兰氏阴性细胞膜。从建议中获得的知识 研究将使建立计算模型来识别新的SLP和急需的 疫苗靶标。

PROJECT SUMMARY The outer membrane in Gram-negative bacteria is a dynamic interface that mediates bacterial interaction with the host by displaying proteins on its surface. The recently discovered surface-exposed lipoproteins (SLPs) play critical roles in pathogenesis, including iron acquisition, adhesion, immune evasion and serve as valuable vaccine targets. Despite their biomedical importance, the mechanism underlying lipoprotein localization to the cell surface is the least understood aspect of bacterial envelope biogenesis. The long- term goal of research in my laboratory is to define the mechanism of lipoprotein targeting and export to the bacterial cell surface. We expect that groups of lipoproteins with similar topologies and/or structural features share dedicated assembly pathways. Improving our understanding of molecular determinants for export will enable the development of predictive computational models for lipoprotein localization and genomic identification of SLPs. One SLP subfamily includes lipoproteins that depend on a partner β- barrel outer membrane protein (OMP) for surface exposure. We discovered the RcsF lipoprotein in Escherichia coli as the first example of this type. We further discovered that the highly conserved and essential β-barrel assembly machinery (Bam) complex plays a critical role in the biogenesis of RcsF, uncovering the novel function of the Bam complex in lipoprotein biogenesis. Here, we propose to use a combination of genetics, biochemistry, and mass spectrometry approaches to identify the molecular mechanism by which the Bam complex displays lipoproteins on the cell surface. We are specifically interested in how the Bam complex recognizes lipoproteins and coordinates lipoprotein surface exposure with OMP assembly. The completion of the proposed studies will substantially expand our understating of biogenesis of SLPs and the Gram-negative cell envelope. The knowledge gained from the proposed studies will enable formulation of computational models for identification of novel SLPs and much-needed vaccines targets.