Influence of chloroplastic photo-oxidative stress on mitochondrial alternative oxidase capacity and respiratory properties:: A case study with arabidopsis yellow variegated 2
Influence of chloroplastic photo-oxidative stress on mitochondrial alternative oxidase capacity and respiratory properties:: A case study with arabidopsis yellow variegated 2
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DOI：
10.1093/pcp/pcn031
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发表时间：
2008-04-01
影响因子：
4.9
通讯作者：
Noguchi, Ko
中科院分区：
文献类型：
--
作者：
Yoshida, Keisuke;Watanabe, Chihiro;Noguchi, Ko
线粒体替代氧化酶（AOX）是植物中独特的呼吸末端氧化酶，可催化浪费能量的抗氰化物（CN）呼吸。尽管已经证明叶片AOX在高光（HL）条件下上调，但光上调AOX的体内机制仍不清楚。在本研究中，我们使用拟南芥叶杂色突变体黄色杂色 2 (var2) 并将植物暴露于 HL，检查叶绿体中的光氧化应激是否调节线粒体呼吸特性，特别是 AOX 能力。 var2 突变体缺乏修复受损 PSII 所需的 FtsH2 金属蛋白酶。事实上，var2-1 甚至在 HL 治疗之前就遭受了光氧化应激。虽然var2-1中三羧酸循环酶和细胞色素c氧化酶的活性与野生型几乎相同，但var2-1中AOX蛋白的量和CN抗性呼吸速率更高。实时 PCR 分析显示，HL 处理在 var2-1 中诱导了一些能量耗散呼吸基因的表达，包括 AOX1a、NDB2 和 UCP5。使用分别含有功能性或非功能性光合装置的绿色或白色部分特异的 var2-1 叶片提取物进行蛋白质印迹，结果表明 HL 处理在绿色部分中诱导了更多的 AOX 蛋白。这些结果表明，过量光引起的光氧化应激参与了呼吸基因表达的调节和呼吸特性的调节，尤其是 AOX 上调。
Mitochondrial alternative oxidase (AOX), the unique respiratory terminal oxidase in plants, catalyzes the energy-wasteful cyanide (CN)-resistant respiration. Although it has been demonstrated that leaf AOX is up-regulated under high-light (HL) conditions, the in vivo mechanism of AOX up-regulation by light is still unknown. In the present study, we examined whether the photo-oxidative stress in the chloroplast modulates mitochondrial respiratory properties, especially the AOX capacity, using Arabidopsis leaf-variegated mutant yellow variegated 2 (var2) and exposing plants to HL. var2 mutants lack FtsH2 metalloprotease required for the repair of damaged PSII. Indeed, var2-1 suffered from photo-oxidative stress even before the HL treatments. While the activities of tricarboxylic acid cycle enzymes and cytochrome c oxidase in var2-1 were almost identical to those in the wild type, the amount of AOX protein and the CN-resistant respiration rate were higher in var2-1. Real-time PCR analysis revealed that HL treatment induced the expression of some energy-dissipating respiratory genes, including AOX1a, NDB2 and UCP5, more strongly in var2-1. Western blotting using var2-1 leaf extracts specific to green or white sectors, containing functional or non-functional photosynthetic apparatus, respectively, revealed that more AOX protein was induced in the green sectors by the HL treatment. These results indicate that photo-oxidative stress by excess light is involved in the regulation of respiratory gene expression and the modulation of respiratory properties, especially the AOX up-regulation.