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Evidence of a significant role of glutathione reductase in the sulfur assimilation pathway.
The Plant Journal ( IF 7.2 ) Pub Date : 2020-01-11 , DOI: 10.1111/tpj.14621
Anner Cohen 1, 2 , Yael Hacham 1, 2 , Yochai Welfe 1, 2 , Soliman Khatib 1, 2 , Jean-Christophe Avice 3 , Rachel Amir 1, 2
Affiliation  

With the objective of studying the role of glutathione reductase (GR) in the accumulation of cysteine and methionine, we generated transgenic tobacco and Arabidopsis lines overexpressing the cytosolic AtGR1 and the plastidic AtGR2 genes. The transgenic plants had higher contents of cysteine and glutathione. To understand why cysteine levels increased in these plants, we also used gr1 and gr2 mutants. The results showed that the transgenic plants have higher levels of sulfite, cysteine, glutathione and methionine, which are downstream to adenosine 5' phosphosulfate reductase (APR) activity. However, the mutants had lower levels of these metabolites, while the sulfate content increased. A feeding experiment using 34 SO4 2- also showed that the levels of APR downstream metabolites increased in the transgenic lines and decreased in gr1 compared with their controls. These findings, and the results obtained from the expression levels of several genes related to the sulfur pathway, suggest that GR plays an essential role in the sulfur assimilation pathway by supporting the activity of APR, the key enzyme in this pathway. GR recycles the oxidized form of glutathione (GSSG) back to reduce glutathione (GSH), which serves as an electron donor for APR activity. The phenotypes of the transgenic plants and the mutants are not significantly altered under non-stress and oxidative stress conditions. However, when germinating on sulfur-deficient medium, the transgenic plants grew better, while the mutants were more sensitive than the control plants. The results give substantial evidence of the yet unreported function of GR in the sulfur assimilation pathway.

中文翻译:

谷胱甘肽还原酶在硫同化途径中发挥重要作用的证据。

为了研究谷胱甘肽还原酶(GR)在半胱氨酸和蛋氨酸积累中的作用,我们生成了过表达胞质AtGR1和质体AtGR2基因的转基因烟草和拟南芥品系。转基因植物的半胱氨酸和谷胱甘肽含量较高。为了了解为什么这些植物中的半胱氨酸水平会增加,我们还使用了gr1和gr2突变体。结果表明,转基因植物具有较高水平的亚硫酸盐,半胱氨酸,谷胱甘肽和蛋氨酸,它们在腺苷5'磷酸硫酸还原酶(APR)活性的下游。但是,突变体的这些代谢物含量较低,而硫酸盐含量却增加了。使用34 SO4 2-的饲养实验还显示,与对照相比,转基因品系中APR下游代谢产物的水平增加,而gr1则下降。这些发现以及从与硫途径相关的几个基因的表达水平获得的结果表明,GR通过支持APR(该途径中的关键酶)的活性,在硫同化途径中起着至关重要的作用。GR将谷胱甘肽(GSSG)的氧化形式再循环回还原还原为APR活性的电子供体的谷胱甘肽(GSH)。在非胁迫和氧化胁迫条件下,转基因植物和突变体的表型没有显着改变。但是,当在缺硫的培养基上发芽时,转基因植物生长得更好,而突变体比对照植物更敏感。结果提供了大量证据证明GR在硫同化途径中的功能尚未报道。
更新日期:2020-01-11
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