CAREER: Evolution and Engineering of Cellular Bet-hedging Devices

该奖项由分子和细胞生物科学部的系统和合成生物学项目资助，旨在解决进化生物学中的一个经典问题：了解生物体如何适应不断变化的环境。许多生物依靠下注对冲策略来应对不可预测和波动的环境。从细菌的抗生素耐受性到哺乳动物的免疫多样性，这种广泛的生物学特性是多种现象的基础。例如，微生物种群可以通过允许单个细胞在多种表型之间随机过渡来增强其适应性。由此产生的种群多样性确保了一些细胞能够很好地适应不可预见的环境变化。揭示这些自适应开关机制是理解微生物进化和生命在不断变化的环境中的关键。最近，有人提出，朊病毒——最初被发现是哺乳动物神经退行性疾病的原因——是真菌中的对冲因子，维持以促进在波动环境中的生存。朊病毒蛋白可以在多种构象状态之间转换。转化为朊病毒状态已被证明可以产生新的、可遗传的表型，这在许多条件下是有益的。这个项目的首要目标是测试朊病毒下注对冲假设。根据理论，投注对冲要素的表型转换率随着环境波动的速率而进化。该项目的一个中心焦点将是通过研究规定的、波动的环境选择中的朊病毒转换来验证这些预测。第二个重点将是使用合成生物学方法来重新设计朊病毒下注对冲设备，从而探索如何在这些元素中编码自适应特性。这些研究将需要开发新的遗传工具，以及创新技术，如微流控平台，以模拟复杂的环境，并以超越传统生物实验能力的方式研究细胞。这项工作将对我们对进化、发育和细胞系统的基本理解产生广泛的影响。该项目还将阐明朊病毒的不同作用，这是微生物世界中正在出现的常见的独特元素。最后，提出的工作将对合成生物学产生变革性的影响，为合理地设计一系列细胞功能提供新的方案。对多学科方法的关注，包括实验和理论，将为各个层次的学生提供令人兴奋的机会，为这个很大程度上未被探索，但重要的生物学领域做出贡献。该项目的一个广泛目标是激励和训练从K-12到研究生院的学生从概念上思考定量、跨学科和工程方法如何帮助理解生活。在将要开展的具体活动中，K-12教育将受到波士顿大学夏季挑战赛“系统与合成生物学训练营”的影响，这是一个面向高中生的住宿夏季项目。开发的实践活动将通过激励大使计划翻译给广大的高中观众。在本科阶段，iGEM活动将扩大，每年将有几名本科生通过该项目得到指导。在研究生阶段，将开设一门新的定量系统生物学综合课程。最后，该项目将促进芯片实验室系统中生物实验小型化和自动化的令人兴奋的技术发展。为使设备设计和操作软件免费提供的基础设施将被实施，以便使该技术广泛使用，并使学生有机会随时建立想法的原型。

The award, funded by the Systems and Synthetic Biology Program in the Division of Molecular and Cellular Biosciences, addresses a classic problem in evolutionary biology: understanding how organisms adapt in ever-changing environments. Many organisms rely on bet-hedging strategies to deal with unpredictable and fluctuating environments. This widespread biological trait underlies diverse phenomena from antibiotic tolerance in bacteria to immune diversity in mammals. For example, a microbial population can enhance its fitness by allowing individual cells to stochastically transition among multiple phenotypes. The resulting population diversity ensures that some cells are well-adapted for an unforeseen environmental change. Uncovering these adaptive switching mechanisms is key to understanding microbial evolution and life in ever-changing environments. Recently, it was proposed that prions - originally discovered as the cause of neurodegenerative diseases in mammals - are bet-hedging elements in fungi, maintained to promote survival in fluctuating environments. Prion proteins can switch between multiple conformational states. Conversion to a prion state has been shown to generate new, heritable phenotypes, which are beneficial in many conditions. The overarching goal of this project is to test the prion bet-hedging hypothesis. According to theory, phenotypic switching rates of bet-hedging elements evolve to be in tune with the rate of environmental fluctuations. A central focus of the project will be to test these predictions by studying prion switching in prescribed, fluctuating environmental selection. A second focus will be to use synthetic biology approaches to de novo engineer prion bet-hedging devices, thereby exploring how adaptive properties might be encoded in these elements. These studies will require the development of new genetic tools, as well as innovative technologies, such as microfluidic platforms, for simulating complex environments and studying cells in ways that are beyond the capabilities of traditional biological experimentation. This work will have broad implications for our basic understanding of evolution, development, and cellular systems. The project will also shed light on the diverse roles of prions, unique elements that are emerging to be common in the microbial world. Finally, the proposed work will have a transformative impact on synthetic biology, enabling new schemes for rationally engineering a wide array of cellular functions.The focus on multidisciplinary approaches, both experimental and theoretical, will provide exciting opportunities for students of all levels to contribute to this largely unexplored, but significant, area of biology. A broad goal of the project is to inspire and train students from K-12 to graduate school to think conceptually about how quantitative, interdisciplinary, and engineering approaches can help in understanding life. Among the specific activities to be pursued, K-12 education will be impacted by developing a 'systems & synthetic biology bootcamp' for Boston University's Summer Challenge, a residential summer program for high school students. The hands-on activities developed will be translated to a broad high school audience via the Inspiration Ambassadors Program. At the undergraduate level, iGEM activities will be expanded and several undergraduates per year will be mentored via the project. At the graduate level, a new integrated course on quantitative systems biology will be developed. Finally, the project will promote exciting technological developments for miniaturizing and automating biological experimentation within lab-on-a-chip systems. Infrastructure for making device designs and operating software freely-available will be implemented in order to make the technology widely accessible and allow students the opportunity to readily prototype ideas.