Cooperation and Cheating in Bacterial Quorum Sensing

细菌群体感应中的合作与作弊

• 批准号: 0843102
• 负责人: Martin Schuster
• 金额: $ 49.5万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-03-15 至 2013-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0843102&HistoricalAwards=false
• 关键词: Cooperation; Cheating; Bacterial; Quorum; Sensing

Scientific research. There has been an explosion of research directed at understanding the mechanisms of how bacteria communicate and cooperate to perform a variety of multicellular behaviors. Not until very recently have microbiologists also begun to investigate these behaviors from the perspective of social evolution. Dr. Schuster's long-term goal is to integrate mechanistic and evolutionary approaches to investigate communication, also termed quorum sensing (QS), and cooperation in the model bacterium Pseudomonas aeruginosa. P. aeruginosa communicates via diffusible acyl-homoserine lactone (acyl-HSL) signals to coordinate the expression of hundreds of genes, many of which encode extracellular factors. Acyl-HSL QS is a widespread phenomenon in bacteria and regulates diverse group behaviors such as light production, virulence, and biofilm formation. The specific objective of this project is to conduct a comprehensive characterization of novel forms of social behavior. Initially, the focus will be on the recently discovered signal-blind obligate cheating and re-evolved cooperation phenomenon that the Schuster group identified during an experimental evolution study of P. aeruginosa. The obligate cheaters do not contribute to the production of quorum-controlled public goods because they harbor a loss-of-function mutation in the gene encoding the central QS regulator. Such mutants have been isolated from natural environments suggesting that cheaters arise also in vivo. The re-evolved cooperators emerged from cheaters are predicted to harbor mutations elsewhere in the genome that restore QS-dependent phenotypes. Very little is known about the genetic basis of such transitions from an obligate to an autonomous life style. Candidate mutations in the genome of a re-evolved cooperator point towards a novel regulatory mechanism of QS gene expression. The specific aims of this project are to (1) characterize the mutation(s) and underlying molecular mechanisms responsible for the cheater-to-cooperator conversion, (2) screen environmental P. aeruginosa isolates for the presence of social mutations and determine their frequency within the population, and (3) characterize evolutionary fitness and cooperative behavior of the cheater-turned-cooperator under social and asocial conditions. This research is relevant to the evolution of many bacteria that rely on social traits for evolutionary success, and has important implications for our understanding of the evolution of cooperative behavior across all domains of life. Educational impact. The described project provides excellent educational opportunities for students. Dr. Schuster has and will continue to train graduate and undergraduate students in the laboratory. Dr. Schuster will also provide educational opportunities for high-school students through an established program at Oregon State University. He has found that the incorporation of evolutionary concepts in the study of microbiological problems greatly enhances student curiosity and interest. Most experiments are conceptually and technically straight-forward and are particularly well suited for the engagement of high-school and undergraduate students in the scientific process.

科学研究。 旨在了解细菌如何进行交流和合作以执行多种多细胞行为的机制的研究爆炸爆炸。直到最近，微生物学家还开始从社会进化的角度研究这些行为。 Schuster博士的长期目标是整合机械和进化的方法来研究交流，也称为Quorum Sensing（QS），并在模型细菌铜绿假单胞菌中进行合作。铜绿假单胞菌通过可扩散的酰基 - 耶洛舍酮内酯（酰基-HSL）信号进行通信，以协调数百个基因的表达，其中许多基因涵盖了细胞外因子。酰基-HSL QS是细菌中广泛的现象，可以调节各种群体行为，例如光产生，毒力和生物膜形成。该项目的具体目标是对新型社会行为的全面表征进行全面表征。最初，重点将放在最近发现的信号盲文作弊和重新进化的合作现象上，该现象是舒斯特组在铜绿假单胞菌的实验进化研究中确定的。专性作弊者没有促进法定控制的公共物品的生产，因为它们具有编码中央QS监管机构的基因丧失功能突变。这种突变体已从自然环境中分离出来，表明作弊者在体内也出现。从作弊者中出现的重新进化的合作者被预计会在基因组中其他位置恢复QS依赖性表型的突变。 关于从义务到自主生活方式的这种过渡的遗传基础知之甚少。 重新进化的合作者基因组中的候选突变指向QS基因表达的新调节机制。 该项目的具体目的是（1）表征负责作弊者转换的突变和基本分子机制，（（2）屏幕环境P.铜绿假单胞菌分离株，以确定人群中的频率并确定其在人群中的频率，以及（3）表征进化的适应和合作的校友，并在整个社交中进行了调整和辅助行为。 这项研究与许多依赖社会特征为进化成功的细菌的进化有关，并且对我们理解合作行为在生活的所有领域的发展具有重要意义。 教育影响。 所描述的项目为学生提供了极好的教育机会。 舒斯特博士已经并且将继续在实验室培训毕业生和本科生。 舒斯特博士还将通过俄勒冈州立大学的一项既定课程为高中生提供教育机会。他发现，将进化概念纳入微生物问题的研究极大地增强了学生的好奇心和兴趣。 大多数实验在概念上和技术上都是直接的，特别适合于高中和本科生参与科学过程。