Phosphorylation and ubiquitination of immune sensory complexes in innate immune s

描述（由申请人提供）：植物和动物依靠免疫感觉复合物通过识别进化上保守的病原体成分来检测感染。植物免疫传感器FLS2是哺乳动物toll样受体（TLR）的结构和功能同源物，可识别细菌鞭毛蛋白，并通过与受体样激酶BAK1结合启动免疫信号传导。目前尚不清楚FLS2/BAK1受体复合物如何激活细胞内信号级联反应。我们已经确定了BAK1激酶的两个重要磷酸化底物。BIK1是一种FLS2/BAK1相关的胞质激酶，在鞭毛蛋白感知下被FLS2/BAK1受体复合物迅速磷酸化并释放，以传播免疫信号。FCU是一种E3泛素连接酶，在鞭毛蛋白刺激下与FLS2结合并泛素化FLS2受体。BIK1转磷酸化BAK1/FLS2，进而增强BAK1在FCU上的磷酸化。本应用程序的目的是研究BIK1和FCU作为会聚成分在将先天免疫信号从受体复合物传导到下游细胞内事件中的作用，以及磷酸化和泛素化在激活和调节免疫感觉复合物中的生物学意义。有三个具体目的：1)阐明受体相关激酶在先天免疫信号传导中的作用。2)确定E3泛素连接酶在先天免疫信号传导中的作用。3)表征PAMP受体复合物的泛素化。非自我识别分子结构的最新进展揭示了多细胞真核生物的微生物感知和先天免疫信号传导机制的显著保守性。磷酸化和泛素化是调节许多细胞和生物体过程的两个关键机制，包括先天免疫。拟南芥遗传学和基因组学的力量为理解这两种普遍调控机制在整个生物体水平上的功能提供了一个很好的模型。因此，本研究将为信号转导提供新的认识，并有助于理解先天免疫信号和免疫感觉复合物的功能。

DESCRIPTION (provided by applicant): Plants and animals rely on immune sensory complexes to detect infection by recognizing evolutionarily conserved pathogen components. Plant immune senor FLS2, a structural and functional ortholog of mammalian Toll-like receptors (TLR), recognizes bacterial flagellin and initiates immune signaling by association with a receptor-like kinase BAK1. It remains unknown how FLS2/BAK1 receptor complex activates intracellular signaling cascades. We have identified two important phosphorylation substrates of BAK1 kinase. BIK1, an FLS2/BAK1-associated cytosolic kinase, is rapidly phosphorylated and released from FLS2/BAK1 receptor complex upon flagellin perception to propagate immune signaling. FCU, an E3 ubiquitin ligase, associates with FLS2 upon flagellin stimulation and ubiquitinates FLS2 receptor. BIK1 transphosphorylates BAK1/FLS2, which in turn enhances BAK1 phosphorylation on FCU. The objective of this application is to examine the role of BIK1 and FCU as convergent components in transducing innate immune signaling from receptor complexes to downstream intracellular events, and the biological significance of phosphorylation and ubiquitination in activating and regulating immune sensory complexes. Three specific aims are 1) Elucidate the role of receptor-associated kinase in innate immune signaling. 2) Determine the function of E3 ubiquitin ligase in innate immune signaling. 3) Characterize the ubiquitination of PAMP receptor complexes. Recent advance on the molecular architecture of nonself recognition has revealed remarkable conservation in the mechanisms of microbial perception and innate immune signaling in multicellular eukaryotes. Phosphorylation and ubiquitination are two key mechanisms in regulating many cellular and organismal processes, including innate immunity. The power of Arabidopsis genetics and genomics provides an excellent model to understand the functions of these two universal regulatory mechanisms at the whole organism level. Thus, the proposed research will provide new insight on signal transduction in general and contribute to the understanding of innate immune signaling and immune sensory complex function. PUBLIC HEALTH RELEVANCE: Phosphorylation and ubiquitination are two key mechanisms in regulating many cellular and organismal processes in different organisms. Deciphering the molecular and biochemical mechanisms of immune sensory complex regulation and activation by phosphorylation and ubiquitination will contribute to our general understanding of cellular signaling and host innate immunity. Given the considerable similarities of innate immunity among multicellular eukaryotes, we anticipate that our research will have broad impact on the study of innate immunity and signal transduction in general.