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: 8581055
• 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/8581055
• 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; computerized data processing; cost; cystic fibrosis patients; density; deviant; insight; instructor; interest; medical schools; mortality; mutant; pathogen; pressure; prevent; public health relevance; quorum sensing; research study; 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)：本次重新提交的K08医生-科学家职业生涯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)的肺部和危重护理医学研究员过渡到代理讲师，目前正在E·彼得·格林伯格的微生物学系实验室进行研究。我的近期目标是继续我的研究，研究我作为研究员发起的群体感知的演变。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的过程中，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，我还保护研究时间和必要的机构支持，以实现我独立调查的长期目标。这包括一个由内科科学家和临床医生组成的指导委员会，除了格林伯格博士，以确保我在这个奖项的任期内继续取得进步。我建议在这一应用中进行以下研究：铜绿假单胞菌是发病率和死亡率的主要原因 在遗传性疾病囊性纤维化(CF)中。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肺炎。铜绿假单胞菌参与群体感应，这是一种依赖于细胞密度的细胞间信号机制，协调群体行为，包括产生毒力因子和分泌的蛋白酶。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，其中许多基因编码与分泌产物的产生有关的蛋白质。这种被分泌的产品是“公共产品”，可供整个社区使用，而不仅仅是生产细胞。因此，群体感知很容易受到社会作弊的影响，即个人突变LasR，以便在不承担生产的新陈代谢成本的情况下从公共产品中获益。在CF肺中，LasR突变的频率很高，这些在肺内从头进化的LasR突变与CF相关肺部疾病的发生和发展有关。在实验室中，铜绿假单胞菌LasR突变体可以在需要群体感应控制的分泌型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，这些LasR突变体实现了与野生型的种群平衡。在我最初的实验中，我证明了腺苷的可用性可以防止LasR突变的出现，腺苷是一种“私人物品”和群体感应受控营养物质。这为民众提供了一种机制，以防范越轨行为。我的建议试图通过回答以下问题来建立这些初步实验的基础：(1)野生型和LasR突变体通过什么机制实现彼此之间的平衡？因为群体感应需要足够的协作者密度，LasR突变体的出现应该会通过将协作者的数量减少到阈值以下而导致种群崩溃，但这种情况并没有发生；我寻找原因。(2)空间结构是否影响LasR突变体的出现和频率？感染环境，包括CF肺，可能是结构化的，我建议研究空间结构对 LasR突变体在种群中出现的能力。最后，(3)提出肺是一个支持LasR突变体出现的独特环境。我计划通过收集100或更多的铜绿假单胞菌环境样本来检验这一假设，并检查它们的LasR突变。这项提案中描述的实验将促进我们对合作行为进化的了解 并深入了解肺循环的生态。