Nutritional regulation of pathogenesis in Staphylococcus aureus

7.项目摘要/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，但大部分时间作为共生细菌，定植于30%-50%的 无症状的人口。候选疫苗对高易感人群显示出希望，但 预防葡萄球菌感染的一般有效方法仍然难以捉摸。此外，机械论 共生病原体转换的基础是复杂的，仍然没有解决，但正在变化的营养 在人类宿主的各种环境中的可用性可能在通知 细菌决定在不同的生活方式之间切换。全球转录调控因子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的表达。我们的 初步数据表明，Cody活动不是二进制的(即，开或关)。相反，科迪可以感觉到一系列 ILV和GTP的浓度，以产生分级转录和生理反应。那是, 在ILV和GTP消耗增加的情况下，毒素和传播因子依次被诱导。 我们实验室的另一项工作表明，科迪几乎控制着所有已知的毒力基因 金黄色葡萄球菌毒力的三个最重要的调节因素：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 克里斯托弗·蒙哥马利(国立儿童医院)、维克多·托雷斯(纽约大学医学院)和Taeok BAE(印第安纳医学院-西北)，我们将揭开科迪将毒力与 养分可利用性。我们将使用基于LC-MS的代谢组学、共聚焦显微镜、经典分子 遗传学和生物化学：(I)确定Cody调节SAE表达的机制 (2)确定养分供应如何改变SAE双组分系统的活性。 此外，我们还将从机制上探讨科迪如何在金黄色葡萄球菌免疫细胞中抑制毒力。 在皮肤和软组织感染期间，也可以使用金黄色葡萄球菌皮肤病的小鼠模型进行接触。 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，拼命取代 在泛耐药时代，过时的抗生素。

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.