The Photorespiratory BOU Gene Mutation Alters Sulfur Assimilation and Its Crosstalk With Carbon and Nitrogen Metabolism in Arabidopsis thaliana
The Photorespiratory BOU Gene Mutation Alters Sulfur Assimilation and Its Crosstalk With Carbon and Nitrogen Metabolism in Arabidopsis thaliana
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DOI：
10.3389/fpls.2018.01709
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发表时间：
2018-11
影响因子：
5.6
通讯作者：
S. Samuilov;Dominik Brilhaus;N. Rademacher;S. Flachbart;L. Arab;S. Alfarraj;Franziska Kuhnert;S. Kopriva;A. Weber;Tabea Mettler-Altmann;H. Rennenberg
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文献类型：
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作者：
S. Samuilov;Dominik Brilhaus;N. Rademacher;S. Flachbart;L. Arab;S. Alfarraj;Franziska Kuhnert;S. Kopriva;A. Weber;Tabea Mettler-Altmann;H. Rennenberg
本研究旨在阐明光呼吸丝氨酸（Ser）的产生对半胱氨酸（Cys）生物合成的意义。为此目的，硫（S）代谢及其与氮（N）和碳（C）代谢的串扰分析野生型拟南芥和其光呼吸bou-2突变体与受损的甘氨酸脱羧酶（GDC）活性。突变体叶片甘氨酸和丝氨酸的含量在白天和夜间都有所增加。突变体中的高丝氨酸水平不能用光呼吸途径或丝氨酸生物合成的两种替代途径的基因的转录丰度来解释。尽管增强叶面丝氨酸，减少GDC活性介导的硫通量下降到主要的硫库的突变体，作为一个结果，解除管制的基因硫还原和同化。突变体叶片半胱氨酸和谷胱甘肽含量增加。在突变体中，用于甲硫氨酸和硫代葡萄糖苷合成的半胱氨酸的使用减少。突变体中GDC活性的降低下调了卡尔文循环和氮同化基因，上调了糖酵解和三羧酸（TCA）途径的关键酶，并改变了糖和TCA中间产物的积累。因此，光呼吸丝氨酸的产生可以被其他代谢性丝氨酸来源所取代，但这种取代解除了S、N和C代谢之间的串扰。
This study was aimed at elucidating the significance of photorespiratory serine (Ser) production for cysteine (Cys) biosynthesis. For this purpose, sulfur (S) metabolism and its crosstalk with nitrogen (N) and carbon (C) metabolism were analyzed in wildtype Arabidopsis and its photorespiratory bou-2 mutant with impaired glycine decarboxylase (GDC) activity. Foliar glycine and Ser contents were enhanced in the mutant at day and night. The high Ser levels in the mutant cannot be explained by transcript abundances of genes of the photorespiratory pathway or two alternative pathways of Ser biosynthesis. Despite enhanced foliar Ser, reduced GDC activity mediated a decline in sulfur flux into major sulfur pools in the mutant, as a result of deregulation of genes of sulfur reduction and assimilation. Still, foliar Cys and glutathione contents in the mutant were enhanced. The use of Cys for methionine and glucosinolates synthesis was reduced in the mutant. Reduced GDC activity in the mutant downregulated Calvin Cycle and nitrogen assimilation genes, upregulated key enzymes of glycolysis and the tricarboxylic acid (TCA) pathway and modified accumulation of sugars and TCA intermediates. Thus, photorespiratory Ser production can be replaced by other metabolic Ser sources, but this replacement deregulates the cross-talk between S, N, and C metabolism.