Dynamic Characterization of a Model Signal Transduction System

本研究的目的是进一步了解细胞如何对环境信号和压力作出反应，特别是定量研究和模拟这种反应的表型变化。为了实现这一目标，该项目将严格检查模式生物大肠杆菌（E. coli）对营养限制形式的环境应激（特别是无机磷酸盐）的反应动力学。在这些条件下，PhoR/PhoB双组分系统信号通路被激活，最终反应是PhoR/PhoB双组分系统蛋白的基因转录被激活，细胞试图清除日益减少的营养供应。在PhoR/PhoB双组分系统的控制下，将通过直接成像放置在大肠杆菌基因组中的荧光蛋白生物标志物的生产速率来监测对环境磷酸盐变化的响应。定量的蛋白质产量和它的变化之间的细胞群体将进行使用外生荧光视频显微镜与单荧光蛋白敏感性。除了测量响应之外，该项目还将开发简化的双组分系统模型，这些模型在数学上易于处理，并使用随机模拟和有限状态投影方法来预测这些模型中响应的均值和方差。模型的预测可以通过实验进行验证并指导新的实验方向，而实验结果可能需要对简化模型进行修改。通过这项研究，该项目将对细胞对环境信号/应激反应的表型变异机制获得新的定量见解。更广泛的影响本项目为在生命科学或物理科学方面受过传统教育的本科生、研究生和博士后学员提供机会，在物理学和生物学的界面上进行多学科研究。主要研究人员通过他们的机构和参与REU和MARC项目参与研究的本科教育。该项目的主要目标是培养各级多学科科学家。鼓励学生和博士后学员参加重大的国家和国际会议并展示他们的研究，使他们接触到生命和物理科学领域正在进行的研究的广度，这些研究将转化为他们自己工作中的新想法和方法。一般讲座将定期在当地高中班级举行，以激起未来科学家对多学科研究的兴趣。此外，两位主要研究人员都致力于改善生命科学和物理科学的多样性和性别平等。

Intellectual meritThe goal of this research is to further our understanding of how cells respond to environmental signals and stresses and specifically to quantitatively investigate and model phenotypic variations in this response. Towards this goal, this project will critically examine the dynamics of the response of the model organism Escherichia coli (E. coli) to environmental stress in the form of nutrient limitation (specifically, inorganic phosphate). Under these conditions, the PhoR/PhoB two-component system signaling pathway is activated with the ultimate response being the activation of gene transcription of the proteins of the PhoR/PhoB two-component system in an attempt by the cell to scavenge the dwindling supply of nutrient. The response to changes in environmental phosphate will be monitored through direct imaging of the production rate of a fluorescent protein biomarker placed in the E. coli genome under control of the PhoR/PhoB two-component system. Quantification of the protein production rate and its variance among a population of cells will be performed using epi-fluorescence video microscopy with single fluorescent protein sensitivity. Beyond measurement of the response, this project will also develop simplified models of the two-component system which are mathematically tractable and use Stochastic Simulation and Finite State Projection methods to predict both the mean and variance of the response in these models. Predictions from models can be tested experimentally and guide new experimental directions while experimental results may necessitate modifications of the simplified models. Through this, the project will obtain new quantitative insight into the mechanism of phenotypic variation in the cellular response to environmental signals/stresses. Broader ImpactsThis project affords opportunities for undergraduate and graduate students and postdoctoral trainees, classically educated in the life or physical sciences, to conduct multidisciplinary research at the interface of physics and biology. The principal investigators are involved in undergraduate education in research both through their institutions and through participation in REU and MARC programs. A primary goal of this project is to train multidisciplinary scientists at all levels. The students and post-doctoral trainees will be encouraged to attend and present their research at major national and international meetings to expose them to the breadth of research being performed in the life and physical sciences which will translate into novel ideas and approaches in their own work. General lectures will be periodically given to local high school classes to pique the interest of tomorrow's scientists in multidisciplinary research. Further, both principal investigators are committed to improving diversity and gender equality in the life and physical sciences.