Arabidopsis Chloroplastic Ascorbate Peroxidase Isoenzymes Play a Dual Role in Photoprotection and Gene Regulation under Photooxidative Stress
Arabidopsis Chloroplastic Ascorbate Peroxidase Isoenzymes Play a Dual Role in Photoprotection and Gene Regulation under Photooxidative Stress
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DOI：
10.1093/pcp/pcp177
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发表时间：
2010-02-01
影响因子：
4.9
通讯作者：
Shigeoka, Shigeru
中科院分区：
文献类型：
--
作者：
Maruta, Takanori;Tanouchi, Aoi;Shigeoka, Shigeru
虽然位于类囊体膜（tAPX）和基质（sAPX）中的两种叶绿体抗坏血酸过氧化物酶（APX）被认为是细胞内H2 O2水平的关键调节剂，但它们在光氧化胁迫响应中的生理意义仍在讨论中。在这里，我们表征了缺乏tAPX（KO-tAPX）或sAPX（KO-sAPX）的单个突变体。在强光照射或甲基紫精处理下，H2 O2和氧化蛋白积累到更高的水平，在两个突变体植物比野生型植物。另一方面，sAPX和tAPX的情况下，急剧抑制H2 O2响应基因的表达下光氧化应激。有趣的是，在KO-tAPX植物而不是KO-sAPX植物中观察到光氧化胁迫对H2 O2和氧化蛋白和基因表达的积累的最显著影响。目前的研究结果表明，叶绿体APX，但特别是tAPX，是重要的光保护和基因调控下的光氧化胁迫在拟南芥叶片。
Though two types of chloroplastic ascorbate peroxidase (APX) located in the thylakoid membrane (tAPX) and stroma (sAPX) have been thought to be key regulators of intracellular levels of H2O2, their physiological significance in the response to photooxidative stress is still under discussion. Here we characterized single mutants lacking either tAPX (KO-tAPX) or sAPX (KO-sAPX). Under exposure to high light or treatment with methylviologen under light, H2O2 and oxidized proteins accumulated to higher levels in both mutant plants than in the wild-type plants. On the other hand, the absence of sAPX and tAPX drastically suppressed the expression of H2O2-responsive genes under photooxidative stress. Interestingly, the most marked effect of photooxidative stress on the accumulation of H2O2 and oxidized protein and gene expression was observed in the KO-tAPX plants rather than the KO-sAPX plants. The present findings suggest that both chloroplastic APXs, but particularly tAPX, are important for photoprotection and gene regulation under photooxidative stress in Arabidopsis leaves.