Systems Biology of Plant Heterotrimeric G-protein Signaling in Overlapping Pathways Regulating Stomatal Closure

这项研究将研究一种特殊的植物细胞类型对不利环境条件的反应，以提供有关活细胞内信号成分如何相互作用以影响细胞功能的新见解。这种特殊的细胞类型，即保卫细胞，发生在表皮中，成对的保卫细胞包围着称为气孔的微孔，植物通过气孔吸收二氧化碳（光合作用的底物），并不可避免地失去水分。由此产生的更好的理解的监管机制，保卫细胞响应干旱和大气中的二氧化碳水平，可以帮助作物品种的发展，在一系列的生长条件下更高的产量。在这个项目中获得的生物网络的一般见解将提高对失调细胞信号的理解，对生理学，农业和生物技术具有广泛的影响。人员，包括本科研究人员，将在实验和计算生物学的新兴方法交叉培训。主要研究人员将开发一门新课程，向一年级本科生介绍生物网络和其他数学生物学概念，并鼓励STEM参与。由G-α亚基和G-β-γ二聚体组成的异源三聚体G蛋白包含在真菌、动物和植物等多种生物体中发现的普遍存在的信号传导机制。这项研究将研究G蛋白参与保卫细胞干旱和CO2信号网络，以解决G-α亚基是否以及如何竞争或分配它们与特定G-β-γ二聚体的相互作用的基本问题。在植物中，保卫细胞是G蛋白调节的最好理解的单细胞系统。响应激素脱落酸（阿坝;干旱和其他胁迫的指标），并提高CO2浓度，复杂的信号网络被激活的保卫细胞，驱动气孔关闭。本项目将使用遗传分析来确定在阿坝和CO2响应期间，四个G-alpa亚基对三个拟南芥G-beta-gamma二聚体的竞争与分配。该研究将应用蛋白质-蛋白质相互作用的测试来评估新的候选G蛋白相互作用物，并确定G蛋白信号传导如何与保卫细胞的其他已知阿坝和CO2信号传导组分相互作用。该项目将开发新的通用可达性分析和组合逻辑方法来描述收敛或重叠的网络，然后将这些方法应用于获得的新实验数据集，以创建G蛋白，阿坝和CO2信号传导核心组件的新网络模型。开发的用于网络构建的新组合逻辑方法将推进系统生物学的基础知识：它们将适用于任何生物体的定向信号和遗传网络，并将实现范式转变，从假设孤立的线性途径（例如经典上位性分析）到考虑与一组观察结果一致的所有网络架构。因此，这项研究的结果将对生物系统中常见但复杂的串扰现象产生普遍影响。

This research will study a specialized plant cell type's response to adverse environmental conditions to provide new insights into how signaling components within living cells interact with each other to affect cell function. This specialized cell type, the guard cell, occurs in the epidermis, where pairs of guard cells enclose microscopic pores called stomata, through which plants take up CO2 (the substrate for photosynthesis) and, inevitably, lose water. Resultant improved understanding of the regulatory mechanisms by which guard cells respond to drought and atmospheric carbon dioxide levels can assist in development of crop varieties with greater yield under a range of growing conditions. General insights into biological networks gained in this project will improve understanding of dysregulated cell signaling, with broad implications for physiology, agriculture, and biotechnology. Personnel, including undergraduate researchers, will be cross-trained in emerging approaches in both experimental and computational biology. The principal investigators will develop a new course to introduce first year undergraduates to biological networks and other mathematical biology concepts and encourage STEM participation. Heterotrimeric G-proteins, composed of G-alpha subunits and G-beta-gamma dimers, comprise a ubiquitous signaling mechanism found in organisms as diverse as fungi, animals, and plants. This research will study G protein involvement in guard cell drought and CO2 signaling networks to address the fundamental question of whether and how G-alpha subunits compete for or partition their interaction with specific G-beta-gamma dimers. In plants, guard cells are the best understood single cell system of G protein regulation. In response to the hormone abscisic acid (ABA; an indicator of drought and other stresses), and to elevated concentrations of CO2, complex signaling networks are activated in guard cells that drive stomatal closure. This project will use genetic analyses to determine competition vs. partitioning of the four G-alpa subunits for the three Arabidopsis G-beta-gamma dimers during ABA and CO2 responses. The research will apply tests of protein-protein interaction to assess new candidate G protein interactors and to determine how G protein signaling interconnects with other known ABA and CO2 signaling components of guard cells. The project will develop new general reachability analysis and combinatorial logic methods to describe convergent or overlapping networks, and these methods will then be applied to the new experimental datasets obtained to create a new network model of the core components of G protein, ABA, and CO2 signaling. The new combinatorial logic methods for network construction developed will advance fundamental knowledge in systems biology: they will be applicable to directional signaling and genetic networks of any organism, and will enable a paradigm shift from assuming isolated linear pathways (e.g. as in classic epistasis analysis) to considering all network architectures consistent with a set of observations. Thus, the results from this research will have general implications for the common but complex phenomenon of cross-talk in biological systems.