Cytosolic Ascorbate Peroxidase 1 Is a Central Component of the Reactive Oxygen Gene Network of Arabidopsis

• Published in: The Plant cell Vol. 17; no. 1; pp. 268 - 281
• Main Authors: Sholpan Davletova, Ludmila Rizhsky, Hongjian Liang, Zhong Shengqiang, Oliver, David J., Jesse Coutu, Shulaev, Vladimir, Karen Schlauch, Mittler, Ron
• Format: Journal Article
• Language: English
• Published: United States American Society of Plant Biologists 01.01.2005
• Subjects: Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Ascorbate Peroxidases; Chloroplast Proteins; Chloroplasts; Chloroplasts - enzymology; Chloroplasts - genetics; Cytosol - enzymology; Fingers; Gene Expression Regulation, Plant - genetics; Genes; Hydrogen peroxide; Hydrogen Peroxide - metabolism; Leaves; Light; Mitochondria - enzymology; Mitochondria - genetics; NADPH Oxidases - genetics; NADPH Oxidases - metabolism; Oxidation; Oxidative stress; Peroxidases - genetics; Peroxidases - metabolism; Photic Stimulation; Photosynthesis; Plant cells; Plant Leaves - enzymology; Plant Leaves - genetics; Plant metabolism; Plants; Reactive oxygen species; Reactive Oxygen Species - metabolism; RNA; Thylakoids - enzymology; Thylakoids - genetics; Zinc
• ISSN: 1040-4651; 1532-298X; 1532-298X
• DOI: 10.1105/tpc.104.026971

Reactive oxygen species (ROS), such as${\rm O}_{2}{}^{-}$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${\rm O}_{2}{}^{-}$and H2O2during 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${\rm H}_{2}{\rm O}_{2}\text{-scavenging}$enzyme ascorbate peroxidase 1 (APX1), the entire chloroplastic${\rm H}_{2}{\rm O}_{2}\text{-scavenging}$system of Arabidopsis thaliana collapses, H2O2levels 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 H2O2stress 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.