Mechanisms to restrain social cheating from quorum sensing in Pseudomonas aerugin

铜绿假单胞菌群体感应中抑制社会作弊的机制

• 批准号: 8665380
• 负责人: Ajai Dandekar
• 金额: $ 17.58万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2017-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8665380
• 关键词: Acute; Adenosine; Affect; Agar; Award; Bacteria; Behavior; Binding; Burn injury; Carbon; Caseins; Catabolism; Cause of Death; Cell Density; Cells; Chronic; Communities; Cooperative Behavior; Critical Care; Cystic Fibrosis; Diabetic wound; Disease; Ecology; Elements; Energy-Generating Resources; Ensure; Environment; Equilibrium; Evolution; Eye; Frequencies; Funding; Gene Expression; Genes; Genetic Transcription; Goals; Growth; Hereditary Disease; Human; Individual; Infection; Investigation; Keratitis; Knowledge; Laboratories; Life; Liquid substance; Lung; Lung diseases; Maintenance; Mediating; Medicine; Mentors; Metabolic; Metabolism; Microbiology; Morbidity - disease rate; Mutate; Mutation; Nutrient; Pathogenesis; Patients; Peptide Hydrolases; Physicians; Pneumonia; Police; Population; Process; Production; Proteins; Pseudomonas; Pseudomonas aeruginosa; Regulation; Relative (related person); Research; Resources; Sampling; Scientist; Signal Transduction; Structure; System; Testing; Therapeutic Intervention; Time; Universities; Variant; Ventilator; Virulence Factors; Washington; Work; Wound Infection; authority; career; cost; cystic fibrosis patients; density; deviant; insight; instructor; interest; medical schools; mortality; mutant; pathogen; pressure; prevent; public health relevance; quorum sensing; research study; signal processing; social; theories; transcription factor

DESCRIPTION (provided by applicant): This resubmission for a K08 physician-scientist career award is for support to transition to a career of independent investigation in the field of Pseudomonas aeruginosa quorum sensing. I recently transitioned from fellow to Acting Instructor of Pulmonary and Critical Care Medicine at the University of Washington (UW) and am conducting research in the lab of E. Peter Greenberg in the Department of Microbiology. I have the immediate goal of continuing my research into the evolution of quorum sensing that I initiated as a fellow. The Greenberg lab, Pulmonary Division, and the University of Washington all provide outstanding support to me. Dr. Greenberg is an authority on quorum sensing and bacterial pathogenesis, and I will continue to work in his group and its resources as I transition to an independent research career. The Pulmonary Division and the School of Medicine will ensure that, in addition to the funds provided, I have protected time for research and the institutional support necessary to achieve my long-term goal of independent investigation. This includes a mentoring committee composed of physician-scientists and clinicians, in addition to Dr. Greenberg, to ensure my continued progress during the term of this award. I propose the following research in this application: P. aeruginosa is a leading cause of morbidity and mortality in the genetic disease cystic fibrosis (CF). It also causes difficult-to-treat burn and diabetic wound infections, keratitis, and ventilator-associated pneumonia. P. aeruginosa engages in quorum sensing, a cell-density-dependent intercellular signaling mechanism that coordinates group behaviors including production of virulence factors and secreted proteases. P. aeruginosa quorum sensing is mediated in part by the transcription factor LasR. LasR regulates the transcription of hundreds of genes, many of which encode proteins that are involved in the production of secreted products. Such secreted products are "public goods" that are available to an entire community, not only the producing cell. As such, quorum sensing is susceptible to social cheating, wherein individuals mutate LasR so that they gain benefit from public goods without bearing a metabolic cost of production. In the CF lung, the frequency of LasR mutants can be high and these LasR mutants, which evolve de novo in the lung, have been implicated in the pathogenesis and progression of CF-related lung disease. In the laboratory, P. aeruginosa LasR mutants can evolve from the wildtype under conditions where a quorum-sensing-controlled secreted protease is required for growth. LasR mutants benefit from protease production by the wildtype and these LasR mutants achieve a population equilibrium with the wildtype. In my initial experiments, I showed that the emergence of LasR mutants can be prevented by the availability of adenosine, a "private good" and quorum-sensing controlled nutrient. This provides a mechanism for the population to police against deviant behavior. My proposal seeks to build on these initial experiments by answering the following questions: (1) What are the mechanisms by which the wildtype and LasR mutants achieve an equilibrium with one another? Because quorum sensing requires a sufficient density of cooperators, the emergence of LasR mutants should cause population collapse by reducing the number of cooperators below the threshold, but this does not occur; I seek reasons why. (2) Does spatial structure affect the emergence and frequency of LasR mutants? Infectious settings, including the CF lung, are likely to be structured and I propose to study the effects of spatial structure on the ability of LasR mutants to emerge in a population. Finally, (3), it has been proposed that the CF lung is a singular environment that supports the emergence of LasR mutants. I plan to test this hypothesis by collecting 100 or more environmental samples of P. aeruginosa and examining them for lasR mutations. The experiments described in this proposal will advance our knowledge of the evolution of cooperative behavior and give insight into the ecology of the CF lung.

描述（由申请人提供）：此次重新提交 K08 医师科学家职业奖是为了支持过渡到铜绿假单胞菌群体感应领域的独立研究职业。我最近从华盛顿大学 (UW) 肺科和重症监护医学的研究员转为代理讲师，并在微生物学系的 E. Peter Greenberg 实验室进行研究。我的近期目标是继续我作为研究员发起的群体感应进化的研究。格林伯格实验室、肺科和华盛顿大学都为我提供了出色的支持。格林伯格博士是群体感应和细菌发病机制方面的权威，在我过渡到独立研究生涯时，我将继续在他的团队及其资源中工作。肺科和医学院将确保，除了提供的资金外，我还拥有保护研究时间和实现独立调查长期目标所需的机构支持。除格林伯格博士外，这还包括一个由医师科学家和临床医生组成的指导委员会，以确保我在获奖期间不断取得进步。我在此申请中提出以下研究： 铜绿假单胞菌是发病率和死亡率的主要原因 遗传病囊性纤维化（CF）。它还会导致难以治疗的烧伤和糖尿病伤口感染、角膜炎和呼吸机相关性肺炎。铜绿假单胞菌参与群体感应，这是一种细胞密度依赖性细胞间信号传导机制，可协调群体行为，包括毒力因子和分泌蛋白酶的产生。铜绿假单胞菌群体感应部分由转录因子 LasR 介导。 LasR 调节数百个基因的转录，其中许多基因编码参与分泌产物生产的蛋白质。这些分泌的产品是“公共物品”，可供整个群体使用，而不仅仅是生产细胞。因此，群体感应很容易受到社会欺骗的影响，即个体对 LasR 进行突变，以便他们从公共物品中受益，而无需承担生产的代谢成本。在 CF 肺中，LasR 突变体的频率可能很高，这些在肺中从头进化的 LasR 突变体与 CF 相关肺部疾病的发病机制和进展有关。在实验室中，铜绿假单胞菌 LasR 突变体可以在生长需要群体感应控制的分泌蛋白酶的条件下从野生型进化而来。 LasR 突变体受益于野生型产生的蛋白酶，并且这些 LasR 突变体实现了与野生型的群体平衡。在我最初的实验中，我证明了可以通过腺苷（一种“私人物品”和群体感应控制的营养素）的可用性来防止 LasR 突变体的出现。这为人们提供了一种监督异常行为的机制。我的建议旨在通过回答以下问题来建立在这些初步实验的基础上：（1）野生型和 LasR 突变体通过什么机制实现彼此平衡？由于群体感应需要足够的合作者密度，LasR突变体的出现应该会通过将合作者数量减少到阈值以下来导致群体崩溃，但这并没有发生；我寻找原因。 (2)空间结构是否影响LasR突变体的出现和频率？传染性环境，包括 CF 肺，很可能是结构化的，我建议研究空间结构对 LasR 突变体在群体中出现的能力。最后，(3)，有人提出 CF 肺是支持 LasR 突变体出现的单一环境。我计划通过收集 100 个或更多铜绿假单胞菌环境样本并检查它们的 lasR 突变来检验这一假设。本提案中描述的实验将增进我们对合作行为演化的了解 并深入了解 CF 肺的生态。