Cytosolic ascorbate peroxidase 1 is a central component of the reactive oxygen gene network of Arabidopsis
Cytosolic ascorbate peroxidase 1 is a central component of the reactive oxygen gene network of Arabidopsis
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DOI：
10.1105/tpc.104.026971
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发表时间：
2005-01-01
期刊：
影响因子：
11.6
通讯作者：
Mittler, R
中科院分区：
文献类型：
--
作者：
Davletova, S;Rizhsky, L;Mittler, R
活性氧（ROS），如O-2（-）和H2 O2，在植物代谢，细胞信号传导和防御中起着关键作用。在叶细胞中，叶绿体被认为是ROS代谢的焦点。它是光合作用过程中O-2（-）和H2 O2的主要生产者，并且它包含大量已被广泛研究的ROS清除机制。相比之下，叶细胞的胞质ROS清除机制的功能在很大程度上是未知的。在这项研究中，我们表明，在胞质H2 O2清除酶抗坏血酸过氧化物酶1（APX 1）的情况下，整个叶绿体H2 O2清除系统的拟南芥崩溃，H2 O2水平增加，和蛋白质氧化发生。我们进一步确定了特定的蛋白质氧化APX 1缺陷的植物和特征的信号事件，随之而来的敲除Apx 1植物响应于中等水平的光胁迫。利用显性负调控的方法，我们证明了热激转录因子在植物早期感知H2 O2胁迫中起着核心作用。使用敲除植物的NADPH氧化酶D蛋白（敲除RbohD），我们证明，RbohD可能需要在光胁迫期间的ROS信号放大。我们的研究指出，在光胁迫期间保护叶绿体的胞质溶胶中的关键作用，并提供了跨室保护类囊体和基质/线粒体APXs胞质APX 1的证据。
Reactive oxygen species (ROS), such as O-2(-) and H2O2, play a key role in plant metabolism, cellular signaling, and defense. In leaf cells, the chloroplast is considered to be a focal point of ROS metabolism. It is a major producer of O-2(-) and H2O2 during photosynthesis, and it contains a large array of ROS-scavenging mechanisms that have been extensively studied. By contrast, the function of the cytosolic ROS-scavenging mechanisms of leaf cells is largely unknown. In this study, we demonstrate that in the absence of the cytosolic H2O2-scavenging enzyme ascorbate peroxidase 1 (APX1), the entire chloroplastic H2O2-scavenging system of Arabidopsis thaliana collapses, H2O2 levels increase, and protein oxidation occurs. We further identify specific proteins oxidized in APX1-deficient plants and characterize the signaling events that ensue in knockout-Apx1 plants in response to a moderate level of light stress. Using a dominant-negative approach, we demonstrate that heat shock transcription factors play a central role in the early sensing of H2O2 stress in plants. Using knockout plants for the NADPH oxidase D protein (knockout-RbohD), we demonstrate that RbohD might be required for ROS signal amplification during light stress. Our study points to a key role for the cytosol in protecting the chloroplast during light stress and provides evidence for cross-compartment protection of thylakoid and stromal/mitochondrial APXs by cytosolic APX1.