Nutritional regulation of pathogenesis in Staphylococcus aureus

7.项目总结/摘要 金黄色葡萄球菌是威胁生命的皮肤和软组织感染、骨髓炎、 肺炎和心内膜炎，但花了大量的时间作为一个肠道细菌，殖民30-50%的 人口渐近。候选疫苗显示出对高度易感人群的承诺，但 预防葡萄球菌感染的一般有效方法仍然难以捉摸。此外，机械 病原体转换的基础是复杂的，仍然没有解决，但不断变化的营养 人类宿主的各种环境中的可用性可能在告知人类宿主方面发挥着重要作用。 细菌在不同生活方式之间转换的决定。全局转录调节子CodY被激活， 异亮氨酸、亮氨酸、缬氨酸（ILV）和GTP，并调节代谢和毒力基因表达。我们 初步数据表明CodY活性不是二元的（即，开或关）。相反，CodY可以感知一系列 ILV和GTP的浓度以产生分级转录和生理应答。也就是说， 在增加ILV和GTP消耗的条件下，依次诱导毒素和扩散因子。 我们实验室的其他工作表明，CodY控制了几乎所有已知的毒力基因， 与S.金黄色葡萄球菌毒力：Sae双组分系统， 调节蛋白Rot和Agr群体感应系统。与葡萄球菌生物学家合作 Christopher蒙哥马利（全国儿童医院）、维克托托雷斯（纽约大学医学院）和Taeok Bae（印第安纳州医学院-西北），我们将解开CodY将毒力与 养分有效性我们将使用基于LC-MS的代谢组学，共聚焦显微镜，经典分子生物学， 遗传学和生物化学，以（i）确定CodY调节sae表达的机制， 基因座，和（ii）确定养分的可用性如何改变Sae双组分系统的活动。 此外，我们还将探讨CodY如何在S.金黄色免疫细胞 以及在皮肤和软组织感染期间使用S.金黄色皮肤坏死 了解营养信号如何通过CodY等因子整合到毒力调控网络中 可以潜在地为限制宿主损害的新型抗菌剂的合理设计提供信息， 在泛耐药时代淘汰抗生素。

7. Project Summary/Abstract Staphylococcus aureus is the leading cause of life threatening skin and soft tissue infections, osteomyelitis, pneumonia and endocarditis, but spends much of its time as a commensal bacterium, colonizing 30-50% of the population asymptomatically. Vaccine candidates show promise for highly susceptible populations, but a general, effective approach to preventing staphylococcal infections remains elusive. Moreover, the mechanistic basis for the commensal-to-pathogen switch is complex and remains unsolved, but changing nutrient availability in the various environments of the human host likely plays an important role in informing the bacterium's decision to switch between lifestyles. The global transcriptional regulator CodY is activated by isoleucine, leucine, valine (ILV) and GTP, and adjusts metabolism and virulence gene expression. Our preliminary data indicate that CodY activity is not binary (i.e., on or off). Rather, CodY can sense a range of concentrations of ILV and GTP to generate a hierarchical transcriptional and physiological response. That is, under conditions of increasing ILV and GTP depletion, toxins and spreading factors are sequentially induced. Additional work by our lab has shown that CodY controls nearly all of the known virulence genes in conjunction with three of the most important regulators of S. aureus virulence: the Sae two-component system, the regulatory protein Rot, and the Agr quorum-sensing system. In collaboration with staphylococcal biologists Christopher Montgomery (Nationwide Children's Hospital), Victor Torres (NYU School of Medicine), and Taeok Bae (Indiana School of Medicine-NW), we will unravel the mechanistic basis by which CodY ties virulence to nutrient availability. We will use LC-MS based metabolomics, confocal microscopy, classical molecular genetics and biochemistry to (i) determine the mechanisms by which CodY regulates the expression of the sae locus, and (ii) determine how nutrient availability alters the activity of the Sae Two Component System. Additionally, we will explore mechanistically how CodY constrains virulence during S. aureus-immune cell encounters as well as during skin and soft tissue infection using a mouse model of S. aureus dermonecrosis. Understanding how nutrient signals are integrated into the virulence regulatory network by factors like CodY can potentially inform the rational design of novel antimicrobials that limit host damage, desperately replacing obsolete antibiotics in an era of pan-resistance.