Role of amino acids and GTP in Staphylococcus aureus pathogenesis

7.项目概要/摘要。 金黄色葡萄球菌在30-50%的人群中定植，是皮肤和软组织疾病的主要原因 感染、骨髓炎、肺炎和心内膜炎。当医院获得性葡萄球菌 疾病正在减少，特别是危险的S.金黄色葡萄球菌对健康构成重大威胁， 健康的人，尤其是孩子。这些社区获得性感染是最常见的原因 并且对许多第一线和最后一线抗生素具有耐药性（例如， 阿莫西林和万古霉素）。这些抗生素的使用和滥用促进了耐药性的上升， 选择生长;因此最好是使致病能力丧失而不是杀死细菌。 以前的工作表明，S。金黄色葡萄球菌调节蛋白CodY有助于抑制 当被氨基酸异亮氨酸、亮氨酸和缬氨酸（ILV）和鸟苷激活时， 三磷酸（GTP）。在没有活性CodY和抑制、毒素和其他致病因素的情况下 这些细菌的毒性更强此外，在生长过程中保持活性 抑制了依赖CodY的基因因此，CodY可被开发作为抗毒力疗法， 让高危患者自然清除感染。在此之前，必须确定CodY 在感染期间组织内的活性变化。如果是这样，施用ILV的类似物和 防止CodY活性的丧失可能潜在地预防葡萄球菌疾病。在这项建议中，我们力求做到 揭示CodY、宿主营养素和基因表达调控之间关系的两件事：i.） 评估宿主组织是否影响CodY依赖性基因表达，使用体内和离体尖端技术 活体成像和荧光报告物，和ii.）确定葡萄球菌中ILV丰度的增加是否 影响致病性。我们将与CA-葡萄球菌生物学家迈克尔奥托合作 （美国国立卫生研究院）和临床前成像专家领导的克里斯托弗艾博年（乔治敦 大学医学中心）。我们将共同采用多方面的方法， 的CodY功能，并测试这种抗毒力的方法。

7. Project Summary/Abstract. Staphylococcus aureus colonizes 30-50% of the population and is the leading cause of skin and soft tissue infections, osteomyelitis, pneumonia and endocarditis. At a time when hospital-acquired staphylococcal disease is decreasing, particularly dangerous clones of S. aureus pose a major health threat to otherwise healthy individuals, especially children. These community-acquired (CA) infections are the most frequent cause of emergency room visits and are resistant to a number of first- and last-line antibiotics (for example, amoxicillin and vancomycin). The use and misuse of these antibiotics promotes the rise of resistance by selecting for growth; therefore it is preferable to disable the ability to cause disease than to kill the bacteria. Previous work has shown that the S. aureus regulatory protein CodY helps to suppress the production of virulence factors when activated by the amino acids isoleucine, leucine and valine (ILV), and guanosine triphosphate (GTP). In the absence of active CodY and suppression, toxins and other disease-causing factors are elevated and those bacteria are significantly more virulent. Moreover, maintaining activity during growth keeps CodY-dependent genes repressed. Therefore, CodY could be exploited as an anti-virulence therapy and allow at-risk patients to clear the infection naturally. Before doing so, it is essential to establish that CodY activity changes within tissues during infection. If so, administering analogs of ILV and guanine nucleotides that prevent loss of CodY activity could potentially prevent staphylococcal disease. In this proposal we seek to do two things to reveal the relationship between CodY, host nutrients, and regulation of gene expression: i.) assess whether host tissue affects CodY-dependent gene expression using cutting edge in vivo and ex vivo live imaging and fluorescent reporters, and ii.) determine whether increasing ILV abundance in staphylococci during infection affects pathogenicity. We will collaborate with CA-staphylococcal biologist Michael Otto (National Institutes of Health), and preclinical imaging experts led by Christopher Albanese (Georgetown University Medical Center). Together, we will employ a multifaceted approach to gain a deeper understanding of CodY function in vivo and to test this anti-virulence approach.