Different involvement of the mitochondrial, plastidial and cytosolic ascorbate-glutathione redox enzymes in heat shock responses
Different involvement of the mitochondrial, plastidial and cytosolic ascorbate-glutathione redox enzymes in heat shock responses
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DOI：
10.1111/j.1399-3054.2008.01195.x
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发表时间：
2009-03-01
影响因子：
6.4
通讯作者：
De Gara, Laura
中科院分区：
文献类型：
--
作者：
Locato, Vittoria;de Pinto, Maria Concetta;De Gara, Laura
植物在热胁迫下的生存需要激活适当的防御机制，以避免代谢功能的损害。热应激导致细胞内活性氧（ROS）的过度产生。在植物中，抗坏血酸（ASC）-GSH循环在控制ROS水平和细胞氧化还原稳态中起着关键作用。抗坏血酸过氧化物酶（APX）是该循环的酶，主要参与ROS解毒。本研究对烟草亮黄2号培养细胞的胞质、线粒体和质体中的ASC-GSH循环酶进行了分析。还使细胞经受两种不同的热冲击（HS; 35或55 ℃，10分钟），并在两种条件下分离细胞隔室。本文报道的结果表明，中度HS（35 ℃）不影响细胞活力，而细胞暴露于55 ℃ HS诱导程序性细胞死亡（PCD）。关于ASC-GSH循环，分析的三个隔室具有特定的酶谱，其通过HS处理而发生明显改变。细胞质中含有所有ASC-GSH循环酶的最高活性，这里报道的数据表明，它作为整个细胞的氧化还原缓冲液。特别是，胞质APX似乎是最通用的酶，其活性增强后，中度HS和减少PCD诱导过程中，而其他APX同工酶只在细胞经历PCD的影响。在不同的ASC-GSH循环同工酶的变化，允许细胞存活或促进PCD的相关性进行了讨论。
Plant survival under heat stress requires the activation of proper defence mechanisms to avoid the impairment of metabolic functions. Heat stress leads to the overproduction of reactive oxygen species (ROS) in the cell. In plants, the ascorbate (ASC)-GSH cycle plays a pivotal role in controlling ROS levels and cellular redox homeostasis. Ascorbate peroxidase (APX) is the enzyme of this cycle mainly involved in ROS detoxification. In this study, the ASC-GSH cycle enzymes were analysed in the cytosol, mitochondria and plastids of tobacco Bright Yellow-2 cultured cells. The cells were also subjected to two different heat shocks (HSs; 35 or 55 degrees C for 10 min) and the cell compartments were isolated in both conditions. The results reported here indicate that moderate HS (35 degrees C) does not affect cell viability, whereas cell exposure to 55 degrees C HS induces programmed cell death (PCD). In relation to ASC-GSH cycle, the three analysed compartments have specific enzymatic profiles that are diversely altered by the HS treatments. The cytosol contains the highest activity of all ASC-GSH cycle enzymes and the data reported here suggest that it acts as a redox buffer for the whole cells. In particular, the cytosolic APX seems to be the most versatile enzyme, being its activity enhanced after moderate HS and reduced during PCD induction, whereas the other APX isoenzymes are only affected in the cells undergoing PCD. The relevance of the changes in the different ASC-GSH cycle isoenzymes in allowing cell survival or promoting PCD is discussed.