SINGLET OXYGEN RESISTANT 1 links reactive electrophile signaling to singlet oxygen acclimation in Chlamydomonas reinhardtii
SINGLET OXYGEN RESISTANT 1 links reactive electrophile signaling to singlet oxygen acclimation in Chlamydomonas reinhardtii
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DOI：
10.1073/pnas.1116843109
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发表时间：
2012-05-15
影响因子：
11.1
通讯作者：
Niyogi, Krishna K.
中科院分区：
文献类型：
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作者：
Fischer, Beat B.;Ledford, Heidi K.;Niyogi, Krishna K.
莱茵衣藻细胞适应于光反应化学物质或强光处理产生的低水平单线态氧，诱发了一种特定的遗传反应，强烈增加了藻类对随后暴露于通常致命的单线态氧产生条件的耐受性。遗传反应包括各种氧化应激反应和解毒基因的表达增加，如谷胱甘肽过氧化物酶同源基因GPXH/GPX5和sigma级谷胱甘肽- s转移酶基因GSTS1。为了确定参与信号转导和单线态氧介导反应激活的成分，进行了突变体选择。这种选择导致了单线态抗氧1 （sor1）突变体的分离，该突变体对单线态产氧化学物质的耐受性更强，并且GPXH和GSTS1的表达量更高。基于图谱的克隆结果显示，SOR1基因编码一种亮氨酸拉链转录因子，该转录因子控制着自身的表达以及大量氧化应激反应和解毒基因的表达。在许多这些基因的启动子区域，发现一个高度保守的8-bp回文序列元件被富集。该元件是通过增加亲脂性反应性亲电物质（RES）水平诱导GSTS1所必需的，这表明它作为亲电反应元件（ERE）起作用。此外，GSTS1在sor1中的过表达需要ERE，尽管尚不清楚是否通过sor1与ERE的直接结合发生。单线态氧诱导的脂质过氧化后可形成RES，表明RES刺激和sor1介导的解毒基因反应是莱茵冷杉单线态氧诱导的驯化过程的一部分。
Acclimation of Chlamydomonas reinhardtii cells to low levels of singlet oxygen, produced either by photoreactive chemicals or high light treatment, induces a specific genetic response that strongly increases the tolerance of the algae to subsequent exposure to normally lethal singlet oxygen-producing conditions. The genetic response includes the increased expression of various oxidative stress response and detoxification genes, like the glutathione peroxidase homologous gene GPXH/GPX5 and the sigma-class glutathione-S-transferase gene GSTS1. To identify components involved in the signal transduction and activation of the singlet oxygen-mediated response, a mutant selection was performed. This selection led to the isolation of the singlet oxygen resistant 1 (sor1) mutant, which is more tolerant to singlet oxygen-producing chemicals and shows a constitutively higher expression of GPXH and GSTS1. Map-based cloning revealed that the SOR1 gene encodes a basic leucine zipper transcription factor, which controls its own expression and the expression of a large number of oxidative stress response and detoxification genes. In the promoter region of many of these genes, a highly conserved 8-bp palindromic sequence element was found to be enriched. This element was essential for GSTS1 induction by increased levels of lipophilic reactive electrophile species (RES), suggesting that it functions as an electrophile response element (ERE). Furthermore, GSTS1 overexpression in sor1 requires the ERE, although it is unknown whether it occurs through direct binding of SOR1 to the ERE. RES can be formed after singlet oxygen-induced lipid peroxidation, indicating that RES-stimulated and SOR1-mediated responses of detoxification genes are part of the singlet oxygen-induced acclimation process in C. reinhardtii.