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KMID : 0613820100200121777
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Journal of Life Science
2010 Volume.20 No. 12 p.1777 ~ p.1783
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Working Mechanism of Peroxiredoxins (Prxs) and Sulphiredoxin1 (Srx1) in Arabidopsis thaliana
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Kim Min-Gab
Mukhamad Su’udi
Park Sang-Ryeol
Hwang Duk-Ju
Bae Shin-Chul
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Abstract
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Plants generate reactive oxygen species (ROS) as a by-product of normal aerobic metabolism or when exposed to a variety of stress conditions, which can cause widespread damage to biological macromolecules. To protect themselves from oxidative stress, plant cells are equipped with a wide range of antioxidant proteins. However, the detailed reaction mechanisms of these are still unknown. Peroxiredoxins (Prxs) are ubiquitous thiol-containing antioxidants that reduce hydrogen peroxide with an N-terminal cysteine. The active-site cysteine of peroxiredoxins is selectively oxidized to cysteine sulfinic acid during catalysis, which leads to inactivation of peroxidase activity. This oxidation was thought to be irreversible. Recently identified small protein sulphiredoxin (Srx1), which is conserved in higher eukaryotes, reduces cysteine?sulphinic acid in yeast peroxiredoxin. Srx1 is highly induced by H₂O₂-treatment and the deletion of its gene causes decreased yeast tolerance to H₂O₂, which suggest its involvement in the metabolism of oxidants. Moreover, Srx1 is required for heat shock and oxidative stress induced functional, as well as conformational switch of yeast cytosolic peroxiredoxins. This change enhances protein stability and peroxidase activity, indicating that Srx1 plays a crucial role in peroxiredoxin stability and its regulation mechanism. Thus, the understanding of the molecular basis of Srx1 and its regulation is critical for revealing the mechanism of peroxiredoxin action. We postulate here that Srx1 is involved in dealing with oxidative stress via controlling peroxiredoxin recycling in Arabidopsis. This review article thus will be describing the functions of Prxs and Srx in Arabidopsis thaliana. There will be a special focus on the possible role of Srx1 in interacting with and reducing hyperoxidized Cys-sulphenic acid of Prxs.
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KEYWORD
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Peroxiredoxin, sulphiredoxin, reactive oxygen species(ROS), reduction, oxidation
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