Heterotrimeric G Protein Signaling in Arabidopsis

描述（由申请人提供）：在大多数后生动物中，不同的 异源三聚体 G 蛋白复合物将许多不同的上游信号耦合到 不同的下游效应子，如腺苷酸环化酶、离子通道和 磷脂酶。然而，在拟南芥中，只有一个规范 但控制不同植物的异源三聚体 G 蛋白复合物 回应。我们不知道这是如何实现的，也不知道是什么 受体激活该 G 蛋白复合物。我的最新技术进展 小组使用功能获得和功能丧失的方法来理解 拟南芥 G 蛋白亚基的功能将使我们能够确定 该 G 蛋白复合物在各种信号传导途径中的分子作用。那里 该项目的三个重点领域是：生长素对根部发育的控制， 下胚轴发育；以及种子发芽的多信号控制。 具体来说，我们将： 1. 确定 G 蛋白突变体的生长素反应性 和过度表达并检查控制种子的信号串扰 发芽，2. 识别和表征遗传和物理相互作用因素 Galpha 和 Gbeta 使用外源抑制子筛选（包括激活） 诱变和使用胞浆蛋白-蛋白相互作用测定，以及 3. 测试 使用反向遗传推定一小组候选 GPCR 的功能 接近。总之，目标是检验生长素利用的假设 信号转导中的异三聚体 G 蛋白。这项工作还解决了 信号串扰机制长期存在的问题。因为，单身 拟南芥异源三聚体 G 蛋白似乎是多重信号的核心 途径，利用拟南芥进行遗传学研究可能揭示其核心机制 信号集成，这可能会被普遍共享。

DESCRIPTION (provided by applicant): In most metazoans, different heterotrimeric G protein complexes couple many different upstream signals to different downstream effectors such as adenyl cyclase, ion channels, and phospholipases. However, in Arabidopsis, there is only a single canonical heterotrimeric G protein complex that nonetheless controls different plant responses. We do not know how this is accomplished nor do we know what receptors activate this G protein complex. Recent technical advances from my group using both gain- and loss-of-function approaches to understand the function of Arabidopsis G protein subunits will enable us to determine the molecular role of this G protein complex in various signaling pathways. There are three focus areas for this project: auxin control of root development, hypocotyl development; and multi-signal control of seed germination. Specifically, we will: 1. determine auxin responsiveness of G protein mutants and overexpressors and examine the signal cross-talk controlling seed germination, 2. identify and characterize genetic and physical interactors of Galpha and Gbeta using extragenic suppressor screens including activation mutagenesis and using cytosolic protein-protein interaction assays, and 3. test putative functions of a small set of candidate GPCRs using reverse genetic approaches. In summary, the goal is to test the hypothesis that auxin utilizes heterotrimeric G proteins in signal transduction. This work also addresses a longstanding problem on the mechanism of signal cross-talk. Because, the single Arabidopsis heterotrimeric G protein appears to be central to multiple signal pathways, genetic studies using Arabidopsis may reveal the core mechanism of signal integration, which is likely to be shared universally.