Characterization of Legionella virulence mechanisms

军团菌毒力机制的表征

• 批准号: 8736927
• 负责人: Matthias Machner
• 金额: $ 77.16万
• 依托单位: EUNICE KENNEDY SHRIVER NATIONAL INSTITUTE OF CHILD HEALTH & HUMAN DEVELOPMENT
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8736927
• 关键词: Air Conditioning; Alveolar Macrophages; American; Bacteria; Bacterial Infections; Bacterial Proteins; Biological; Breathing; Cells; Centers for Disease Control and Prevention (U.S.); Collaborations; Data; Deposition; Development; Diagnosis; Disease; Elderly; Environment; Equilibrium; Evolution; Fresh Water; Funding; Goals; Guanosine Triphosphate Phosphohydrolases; Habitats; Head; Human; Human Activities; Immune; Immunocompromised Host; Individual; Invaded; Legionella; Legionella pneumophila; Legionnaires' Disease; Lung; Microbe; Molecular; Organism; Pneumonia; Population; Post-Translational Protein Processing; Process; Proteins; Public Health; Research; Research Project Grants; Respiratory Tract Infections; Role; Sequence Homology; Signal Transduction; Signaling Protein; Spain; System; Therapeutic Intervention; Vacuole; Virulence; Water; Work; disorder prevention; enzyme activity; fighting; inhibitor/antagonist; insight; macrophage; man; microorganism; pathogen; protein function; small molecule; three dimensional structure

The purpose of our research is to decipher the molecular mechanisms that allow the bacterium Legionella pneumophila to infect human cells and cause a severe pneumonia known as Legionnaires disease. Since L. pneumophila is ubiquitously found in freshwater habitats such as water fountains, air conditioning systems, or shower heads and faucets, the American population is frequently exposed to this organism. When inhaled by elderly or immunocompromised individuals, L. pneumophila can infect alveolar macrophages resulting in a potentially fatal respiratory infection. According to the Center for Disease Control and Prevention (CDC), the number of diagnosed Legionnaires' disease cases has doubled over the past decade, explaining why this disease is an emerging public health threat. The ability of L. pneumophla to establish a replication vacuole within infected cells is key to its virulence, yet the details of this process are not very well characterized. Over the past funding period, we have continued our study of the intracellular replication cycle of L. pneumophila in order to determine which bacterial molecules contribute to disease development, what their functions are, and how we can interfere with their activity. We have discovered that L. pneumophila uses proteins, so called effectors, that are injected into infected human cells where they manipulate the activity of human signaling proteins such as GTPases. By doing so, the bacterium takes control of the infected cell and reprograms it in a way that the host cell now supports bacterial replication instead of fighting the invading microbe. Remarkably, some of the effectors that are used by L. pneumophila to manipulate our cells have been been acquired during evolution from the host cell itself and are now being used by the bacterium against the host. For instance, we and others discovered that L. pneumophila has a set of effector proteins that attach or remove a post-translational modification to human GTPase in order to control its activity. In collaboration with a group in Spain, we successfully solved the three-dimensional structure of one of these effectors which provided important insight into how this bacterial protein functions at a molecular level. These data now provide a framework for the development of small molecule inhibitors that block the enzymes activity and, thus, its ability to control signaling proteins in human cells. Our work not only yields much-needed insight into the virulence strategies of L. pneumophila and related pathogens, but it also provides important clues about the delicately balanced signaling networks within our own cells and how they contribute to or counteract bacterial infections.

我们研究的目的是破译嗜肺军团菌感染人类细胞并导致一种被称为军团病的严重肺炎的分子机制。 由于嗜肺性乳杆菌普遍存在于淡水栖息地，如饮水机、空调系统、淋浴喷头和水龙头，因此美国人经常接触到这种微生物。当被老年人或免疫功能低下的人吸入时，嗜肺乳杆菌可感染肺泡巨噬细胞，导致潜在的致命呼吸道感染。根据疾病控制和预防中心(CDC)的数据，在过去十年中，被诊断为退伍军人症的病例数量翻了一番，这解释了为什么这种疾病是一个新的公共卫生威胁。 嗜肺乳杆菌在感染细胞内建立复制空泡的能力是其毒力的关键，但这一过程的细节还没有得到很好的描述。在过去的资助期间，我们继续研究嗜肺乳杆菌的细胞内复制周期，以确定哪些细菌分子有助于疾病的发展，它们的功能是什么，以及我们如何干扰它们的活动。我们已经发现嗜肺乳杆菌使用的蛋白质，即所谓的效应器，被注射到受感染的人类细胞中，在那里它们操纵人类信号蛋白的活性，如GTP酶。通过这样做，细菌控制了受感染的细胞，并对其进行了重新编程，使宿主细胞现在支持细菌复制，而不是对抗入侵的微生物。 值得注意的是，嗜肺乳杆菌用来操纵我们细胞的一些效应器是在宿主细胞本身进化过程中获得的，现在正被细菌用来对抗宿主。例如，我们和其他人发现嗜肺乳杆菌有一组效应蛋白，可以附着或移除人类GTP酶的翻译后修饰，以控制其活性。与西班牙的一个研究小组合作，我们成功地解决了其中一个效应器的三维结构，这为这种细菌蛋白质如何在分子水平上发挥作用提供了重要的见解。这些数据现在为开发小分子抑制剂提供了一个框架，这些小分子抑制剂可以阻断酶的活性，从而控制人类细胞中的信号蛋白的能力。 我们的工作不仅为嗜肺乳杆菌和相关病原体的毒力策略提供了亟需的见解，还为我们自己的细胞内微妙平衡的信号网络以及它们如何促进或对抗细菌感染提供了重要线索。