CCaMK-Mediated Changes During Bacterial and Fungal Symbioses

Ca2+/钙调素依赖性蛋白激酶（CCaMK）在植物根系感知固氮细菌共生体并导致固氮根瘤形成的信号转导级联反应中起着关键作用。该项目旨在确定该激酶在根中的作用，因为来自潜在共生体的信号被接收并转导到参与根瘤形成的下游效应器。CCaMK是一种多功能蛋白，其特点是在单个多肽中存在激酶结构域、自抑制结构域、钙调蛋白结合结构域和神经视蛋白样Ca2+结合结构域。CCaMK经历Ca2+调控的两个步骤，首先直接通过其Ca2+结合域，然后间接通过其Ca2+/钙调素结合域。最近的研究表明，CCaMK在细菌和真菌的共生中起着至关重要的作用。在导致固氮的细菌相互作用中，CCaMK直接作用于根毛细胞中由细菌产生的信号分子Nod因子引发的Ca2+振荡的下游。本研究的直接目的是研究CCaMK的结构变化如何控制细菌的入侵以及由此产生的共生关系。此外，该项目还将寻求确定和描述CCaMK潜在的下游互动伙伴。遗传学研究表明，CCaMK位于介导植物与共生体相互作用的信号通路分支点的关键节点上：一个分支导致结瘤，另一个分支导致菌根感染。因此，这个项目可能会导致对真菌和细菌共生的新见解。该项目将使用遗传、生化和细胞方法来解决植物领域的一个开创性问题：微生物相互作用。除了农业和生态意义外，该项目更广泛的影响还包括培养本科生、研究生和博士后。将强调培训对科学感兴趣的少数民族和妇女。现场参与者将体验活跃的生物技术研究实验室的氛围。为了接触到更广泛的受众，华盛顿州立大学团队还将使用华盛顿州高等教育电信系统并组织现场研讨会。

A Ca2+/calmodulin-dependent protein kinase (CCaMK) has been implicated as a key player in the signal transduction cascade that follows perception of nitrogen fixing bacterial symbionts by plant roots and leads to the establishment of nitrogen-fixing root nodules. This project seeks to determine the role of this kinase in roots as signals from potential symbionts are received and transduced to downstream effectors involved in nodule formation. CCaMK, a multi-functional protein, is characterized by the presence of a kinase domain, an autoinhibitory domain, a calmodulin-binding domain and a neural visinin-like Ca2+-binding domain in a single polypeptide. CCaMK undergoes two steps of Ca2+ regulation, first directly through its Ca2+-binding domain and then indirectly through its Ca2+/calmodulin-binding domain. Recent investigations have revealed that CCaMK plays critical roles in both bacterial and fungal symbioses. During bacterial interactions which lead to nitrogen fixation, CCaMK acts immediately downstream of Ca2+ oscillations triggered in root hair cells by the bacterially produced signaling molecule, Nod factor. The immediate goal of this investigation is to study how the structural changes of CCaMK control bacterial invasion and the resulting symbiotic relationship. Furthermore, the project will also seek to identify and characterize CCaMK's potential downstream interaction partner(s). Genetic studies indicate that CCaMK is at a critical juncture of a branch point in the signaling pathway which mediates the interaction of plants with their symbionts: one branch leads to nodulation and the other to mycorrhizal infection. Hence, this project may lead to new insights into fungal as well as bacterial symbioses. This project will use genetic, biochemical and cellular approaches to address a seminal question in the area of plant:microbe interactions. In addition to its agricultural and ecological significance the broader impacts of the project include training undergraduates, graduate students and postdocs. Training of minorities and women who are interested in science will be emphasized. On-site participants will experience the atmosphere of an active biotechnology research laboratory. To reach a wider audience, the WSU team will also use the Washington State Higher Education Telecommunication System and organize onsite workshops.