Networks of Heterotrimeric G alpha Subunit Signaling to K+ Channels in Arabidopsis Guard Cells

G蛋白由三种较小的蛋白质G α、G β和G γ组成，是动物、真菌和植物中重要且普遍存在的细胞蛋白。与G蛋白偶联的信号通路使这些生物能够感知环境并对其做出适当的反应。在植物中，G蛋白帮助植物细胞感知病原菌和水分胁迫。气孔保卫细胞是植物中G蛋白调控的细胞系统之一。保卫细胞是在叶的最外层组织层（表皮）中发现的高度特化的细胞。成对的保卫细胞调节称为气孔的微观孔的打开和关闭，植物通过气孔从空气中吸收二氧化碳进行光合作用，但也通过气孔将水蒸气损失到大气中，从而可能导致脱水胁迫。保卫细胞通过改变气孔的形状和体积来控制气孔的开度，这些过程反过来又受钾和其他溶质的吸收控制。保卫细胞膜中的蛋白质（KAT 1）介导钾的吸收，从而驱动气孔的打开。KAT1蛋白活性被植物激素脱落酸（阿坝）和引起植物疾病的细菌产生的分子抑制。G蛋白作为“中间人”，将阿坝和细菌的信号传递给KAT1蛋白，但G蛋白只是这些反应背后复杂的细胞内信号网络的一个组成部分。该项目将详细阐明细胞内信号蛋白的网络，这些信号蛋白将信号（例如从阿坝）传递到G蛋白并传递到KAT1。这项研究的一个组成部分是开发新的和广泛适用的计算工具，用于理解和预测细胞信号网络。更广泛的影响：这项研究对植物生物学（以及更广泛的社会）具有重要意义，因为它将有助于开发出对感染和环境压力具有更高抗性的作物。这项研究开发的计算方法将广泛适用于任何细胞信号网络，无论生物体。该项目将为本科生、研究生和博士后研究员提供细胞和计算生物学界面的跨学科培训。项目人员将努力提高少数群体在科学领域的代表性，办法是参加促进奇卡诺人和美洲土著科学家协会年度会议的外联和辅导活动，该项目得到网络和管制方案以及数学生物学方案的联合支助。

G proteins, which are composed of three smaller proteins named Galpha, Gbeta, and Ggamma, are important and ubiquitous cellular proteins in animals, fungi, and plants. Signaling pathways that are coupled to G proteins allow these organisms to sense and respond appropriately to their environments. In plants, G proteins help plant cells to sense both pathogenic bacteria and water stress. One of the best understood cellular systems of G protein regulation in plants is the stomatal guard cell. Guard cells are highly specialized cells found in the outermost tissue layer (the epidermis) of the leaf. Pairs of guard cells regulate the opening and closing of microscopic pores called stomata, through which plants take up carbon dioxide from the air for photosynthesis but through which they also lose water vapor to the atmosphere, leading potentially to dehydration stress. The guard cells control the aperture of the stomata by changing their shape and volume, processes that are in turn controlled by the uptake of potassium and other solutes. Proteins (KAT1) in the guard cell membrane mediate the uptake of potassium which drives this stomatal opening. KAT1 protein activity is inhibited by the plant hormone abscisic acid (ABA) and by molecules produced by bacteria that cause plant disease. G proteins serve as "middle-men" that relay the signals from ABA and bacteria to the KAT1 proteins, but G proteins are only one component of the complex intracellular signaling networks underlying these responses. This project will elucidate in detail the networks of intracellular signaling proteins that relay signals (for example from ABA) to G proteins and on to KAT1. An integral component of this research is the development of new and broadly applicable computational tools for understanding and predicting cellular signaling networks. BROADER IMPACTS: This research has significance for plant biology (and more broadly for society) because it will help develop crops with improved resistance to infection and to environmental stress. The computational approaches developed by this research will be broadly applicable to any cellular signaling network, regardless of organism. This project will provide interdisciplinary training to undergraduate and graduate students and post-doctoral fellows at the interface of cell and computational biology. Project personnel will work towards improving the representation of minorities in science by participating in outreach and mentoring activities at the annual SACNAS (Society for the Advancement of Chicano/a and Native American Scientists) conference.This project is supported jointly by the Networks and Regulation and Mathematical Biology Programs.