Kinase mediated signaling in the rice defense response

水稻防御反应中激酶介导的信号传导

• 批准号: 6916984
• 负责人: PAMELA C RONALD
• 金额: $ 28.99万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-01 至 2009-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6916984
• 关键词: biological signal transduction; cell surface receptors; enzyme activity; enzyme mechanism; enzyme structure; flagellin; gene expression; genetic transcription; immunity; phosphorylation; plant genetics; plant physiology; plant proteins; protein kinase; protein protein interaction; rice; tissue /cell culture

DESCRIPTION (provided by applicant): Perception of extracellular signals by cell surface receptors is of central importance to eukaryotic development and immunity. Many of these receptors possess intrinsic protein kinase activity in their cytoplasmic domains (RKs) and regulate transcription of target genes through phosphorylation and dephosphorylation events. Abnormal regulation can lead to a variety of diseases and it is therefore important to understand how RK specificity and function are controlled. In contrast to most protein kinases that are regulated by phosphorylation of the activation segment, a centrally located loop that sits close to the catalytic center, an emerging theme for some RKs is that the juxtamembrane (JM) domain plays a key regulatory role in their activation. In this case, residues in the JM domain perform both positive and negative regulatory functions. In their unphosphorylated state they repress catalytic activity and upon phosphorylation they serve as high affinity binding sites for downstream signaling proteins. Regulation of RK signaling through the JM domain is so far unique to only a few receptor families controlling important cellular processes and consequently there is great interest in exploring the molecular basis for this control. The rice XA21 gene, encoding a RK with leucine rich repeats (LRRs) in the extracellular domain, is a key recognition and signaling determinant in the innate immune response, a pathogen defense pathway widely conserved between plants and animals. XA21 is not autophosphorylated in the activation segment and at least four XA21 binding proteins (Xbs) require phosphorylated residues in the JM region for interaction. These include Xb10, encoding a putative transcriptional regulator and Xb15 encoding a PP2c phosphatase-like protein. Based on these results we hypothesize that the XA21 JM domain plays a key role in XA21 kinase-mediated signal transduction and that JM-binding protein's act as positive or negative regulators to control transcription of defense related genes. To further test this hypothesis we propose to: 1. Determine the role of Xb10 and Xb15 in Xa2'l -mediated and flagellin-activated defense responses. 2. Further characterize the XA21 JM domain, identify Xb kinase interaction domains and assess the role of XA21-dependent phosphorylation 3. Characterize the cellular interactions of XA2jl and Xbs and identify new components in the in vivo complexes.

描述（由申请人提供）：细胞表面受体感知细胞外信号对真核生物发育和免疫至关重要。这些受体中的许多在其胞质结构域（RKs）中具有内在蛋白激酶活性，并通过磷酸化和去磷酸化事件调节靶基因的转录。异常调节可导致多种疾病，因此了解RK特异性和功能是如何控制的非常重要。 与大多数通过激活片段磷酸化调节的蛋白激酶相反，一个位于中心的环靠近催化中心，一些RKs的新兴主题是质膜（JM）结构域在其激活中起关键调节作用。在这种情况下，JM结构域中的残基执行正和负调节功能。在未磷酸化状态下，它们抑制催化活性，磷酸化后，它们作为下游信号蛋白的高亲和力结合位点。通过JM结构域调节RK信号传导到目前为止仅对控制重要细胞过程的少数受体家族是独特的，因此对探索这种控制的分子基础有很大的兴趣。 水稻XA 21基因编码一个胞外区富含亮氨酸重复序列（Leucine rich repeats，LRRs）的RK，是植物和动物间广泛保守的病原体防御途径--先天免疫应答中的关键识别和信号传导决定因子。XA 21在活化区段中不自磷酸化，并且至少四种XA 21结合蛋白（Xbs）需要JM区中的磷酸化残基用于相互作用。这些包括Xb 10，编码一个假定的转录调节因子和Xb 15编码PP 2c磷酸酶样蛋白。 基于这些结果，我们推测XA 21 JM结构域在XA 21激酶介导的信号转导中起关键作用，并且JM结合蛋白作为正或负调节剂控制防御相关基因的转录。为了进一步验证这一假设，我们建议： 1.确定Xb 10和Xb 15在Xa 2 ′ 1介导的和鞭毛蛋白激活的防御反应中的作用。 2.进一步表征XA 21 JM结构域，鉴定Xb激酶相互作用结构域并评估XA 21依赖性磷酸化的作用 3.表征XA 2 jl和Xbs的细胞相互作用并鉴定体内复合物中的新组分。