The alternative oxidase lowers mitochondrial reactive oxygen production in plant cells
The alternative oxidase lowers mitochondrial reactive oxygen production in plant cells
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DOI：
10.1073/pnas.96.14.8271
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发表时间：
1999-07-06
影响因子：
11.1
通讯作者：
McIntosh, L
中科院分区：
文献类型：
--
作者：
Maxwell, DP;Wang, Y;McIntosh, L
除了细胞色素 c 途径外，植物线粒体还有一条替代呼吸途径，该途径由单一同源二聚体蛋白替代氧化酶 (AOX) 组成。使用 AOX 水平改变的转基因培养烟草细胞来检验以下假设：植物线粒体中的替代途径是减少呼吸电子传递过程中产生的活性氧 (ROS) 形成的机制。使用ROS敏感探针2',7'-二氯荧光素二乙酸酯，我们发现AOX的反义抑制导致细胞中ROS水平显着高于野生型细胞，而AOX的过表达导致细胞中ROS丰度较低。激光扫描共聚焦显微镜显示野生型和 AOX 转基因细胞中 ROS 丰度的差异是由线粒体特异性 ROS 形成的变化引起的。使用抗霉素 A 会加剧线粒体 ROS 的产生，从而抑制正常的细胞色素电子传递。此外，发现过度表达 AOX 的细胞编码 ROS 清除酶的基因表达始终较低，包括超氧化物歧化酶基因 SodA 和 SodB，以及谷胱甘肽过氧化物酶。此外，在 AOX 缺陷的细胞中，编码水杨酸结合过氧化氢酶和发病机制相关蛋白的 mRNA 丰度显着更高。这些结果证明 AOX 在降低植物细胞中线粒体 ROS 形成方面发挥着作用。
Besides the cytochrome c pathway, plant mitochondria have an alternative respiratory pathway that is comprised of a single homodimeric protein, alternative oxidase (AOX). Transgenic cultured tobacco cells with altered levels of AOX were used to test the hypothesis that the alternative pathway in plant mitochondria functions as a mechanism to decrease the formation of reactive oxygen species (ROS) produced during respiratory electron transport. Using the ROS-sensitive probe 2',7'-dichlorofluorescein diacetate, we found that antisense suppression of AOX resulted in cells with a significantly higher level of ROS compared with wild-type cells, whereas the overexpression of AOX resulted in cells with lower ROS abundance. Laser-scanning confocal microscopy showed that the difference in ROS abundance among wild-type and AOX transgenic cells was caused by changes in mitochondrial-specific ROS formation. Mitochondrial ROS production was exacerbated by the use of antimycin A,which inhibited normal cytochrome electron transport. In addition, cells overexpressing AOX were found to have consistently lower expression of genes encoding ROS-scavenging enzymes, including the superoxide dismutase genes SodA and SodB, as well as glutathione peroxidase. Also, the abundance of mRNAs encoding salicylic acid-binding catalase and a pathogenesis-related protein were significantly higher in cells deficient in AOX. These results are evidence that AOX plays a role in lowering mitochondrial ROS formation in plant cells.