The Arabidopsis gp91-phox Gene Family and NADPH Oxidase Function

拟南芥 gp​​91-phox 基因家族和 NADPH 氧化酶功能

• 批准号: 0318975
• 负责人: Jeffery Dangl
• 金额: $ 42.5万
• 依托单位: University of North Carolina at Chapel Hill
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-15 至 2007-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0318975&HistoricalAwards=false
• 关键词: Arabidopsis; gp91; phox; Gene; Family

Plants cannot move to defend themselves from aggressions in their environment. Also they do not posses a complex, circulating, cell-based immunological system of defense like vertebrates. However, plants have evolved an immune system for pathogen recognition that initiates a set of cellular responses that collectively stop the intruder or can react and respond to stress situations. Production of Reactive Oxygen Species (ROI) is one of the earlier responses observed after pathogen infection in plants. ROI produced may directly participate in the killing of the invading pathogens, but could also act as a signal that induces further defenses. A plasma membrane bound NADPH oxidase is the likely source of ROI in plants. This oxidase, also known as the respiratory burst oxidase (RBO), was initially described in mammalian macrophages and is a multienzymatic complex that mediate the killing of microbes. This protein is the enzymatic subunit of the NADPH oxidase that uses molecular oxygen to make superoxide. Arabidopsis has a 10 member Atrboh (Arabidopsis thaliana respiratory burst oxidase homologs), gene family, homologous to the animal protein called gp91phox. However, the precise subunit structure of the NADPH oxidase and the regulation of its activation appear to be different than in mammalian macrophages.It is becoming evident that ROI is not an executioner but a signal that mediate the activation of the defenses as well as other responses to the environment and developmental processes. In mammals, multiple isoforms of gp91phox act in different cell types, and perform different functions. Similarly, different NADPH oxidases in plants may also mediates production of apoplastic ROI in different tissues and in responses to different environmental stimuli. For example, our group has shown that AtrbohD and AtrbohF are responsible for the production of ROI during the defense response and that ROI generated through these members of the Atrboh family are required as second messengers in ABA signaling during stomata closure. Also, the oxidative burst mediated by AtrbohC regulates plant cell expansion during root hair formation through the activation of channels that allow calcium to move in and out of the cell.. Interestingly, Nitric Oxide (NO), another reactive molecule that mediates cell death in mammalian macrophages, may regulate plant responses in conjunction to ROI. Studies show that interaction with pathogens trigger NO release, and ROI and NO seem to, then, work synergistically to control the hypersensitive response.The goal of this project is to decipher, using functional genomics tools, the functions of the plant NADPH oxidase gene family. The hypothesis to be tested is that different members of Atrboh, components of the plant NADPH oxidase, control production of ROI during defense response and in developmental processes, PCD and other responses to the environment. The connections between ROI and NO, another important regulator of PCD and other responses, will be also investigated. The identification of the Atrboh genes also enables to study the mechanism that activates the plant NADPH oxidase. This is particularly relevant since important regulatory elements of the mammalian NADPH oxidase appear to be absent in the plant oxidase. Studies will be conducted to identify more components of the ROI signaling, especially those involved in earlier steps of the signal transduction pathway that regulate Atrboh function, as well as putative targets or mediators of ROI-dependent signaling. These studies will allow to further understand the function of ROI during disease resistance responses, as well as in a range of developmental responses mediated by ROI and NO.

植物不能捍卫自己免受环境中的侵略。 而且，它们也没有像脊椎动物这样的复杂，循环，基于细胞的免疫系统防御系统。然而，植物已经发展出一种免疫系统，用于病原体识别，该系统启动了一组细胞反应，这些反应集体阻止入侵者或可以反应并应对压力情况。活性氧（ROI）的产生是植物病原体感染后观察到的早期反应之一。 产生的ROI可能会直接参与杀死入侵的病原体，但也可能充当诱导进一步防御的信号。质膜结合的NADPH氧化酶是植物中ROI的可能来源。最初在哺乳动物巨噬细胞中描述了该氧化酶，也称为呼吸道爆发氧化酶（RBO），是一种多元合并复合物，可介导杀死微生物。该蛋白是使用分子氧制造超氧化物的NADPH氧化酶的酶亚基。拟南芥有10个成员Atrboh（拟南芥呼吸爆发氧化酶同源物），基因家族，与称为GP91Phox的动物蛋白同源。然而，NADPH氧化酶的确切亚基结构及其激活的调节似乎与哺乳动物巨噬细胞中不同。它越来越明显地表明，ROI不是executionution子手，而是一个介导防御性激活以及其他对环境和发展过程的反应的信号。在哺乳动物中，GP91Phox的多种同工型在不同的细胞类型中作用，并执行不同的功能。同样，植物中的不同NADPH氧化酶也可能介导不同组织中的凋亡ROI的产生，并在对不同环境刺激的反应中介导。例如，我们的小组表明，ATRBOHD和ATRBOHF负责在防御响应期间产生ROI，并且由于ABA封闭期间ABA信号的第二招人，需要通过ATRBOH家族的这些成员产生的ROI。同样，由AtrboHC介导的氧化爆发通过激活通道的激活来调节植物细胞的膨胀，从而使钙能够进出细胞。有趣的是，一氧化氮（NO），这是另一种反应性分子，该反应性分子介导哺乳动物巨噬细胞中的细胞死亡，可能调节植物对ROI的结合植物反应。研究表明，与病原体的相互作用触发了无释放，ROI和NO似乎可以协同控制过度敏感的反应。该项目的目的是使用功能基因组学工具（植物NADPH氧化酶基因家族的功能）破译。要检验的假设是，植物NADPH氧化酶的组成部分的不同成员，在国防反应和发育过程中控制ROI的产生，PCD和其他对环境的反应。 ROI和NO之间的连接（PCD的另一个重要调节器与其他响应）也将进行研究。 AtrboH基因的鉴定还可以研究激活植物NADPH氧化酶的机制。这尤其重要，因为在植物氧化酶中，哺乳动物NADPH氧化酶的重要调节元件似乎不存在。将进行研究以识别ROI信号的更多组成部分，尤其是那些参与调节ATRBOH函数的信号转导途径的早期步骤的组件，以及ROI依赖性信号传导的推定目标或介体。这些研究将允许进一​​步了解ROI在疾病抗性反应中的功能，以及在ROI和NO介导的一系列发育反应中。