Deletion of glycine decarboxylase in arabidopsis is lethal under nonphotorespiratory conditions
Deletion of glycine decarboxylase in arabidopsis is lethal under nonphotorespiratory conditions
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DOI：
10.1104/pp.107.099317
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发表时间：
2007-07-01
期刊：
影响因子：
7.4
通讯作者：
Bauwe, Hermann
中科院分区：
文献类型：
--
作者：
Engel, Nadja;van den Daele, Kirsten;Bauwe, Hermann
线粒体多酶甘氨酸脱羧酶（GDC）催化甘氨酸依赖四氢叶酸的分解代谢为5,10-亚甲基四氢叶酸及其副产物NADH、CO 2和NH3。这个反应是光呼吸循环的一部分，有助于单碳代谢。虽然GDC在这两种代谢途径中的重要作用已得到证实，但也有人提出存在旁路反应。因此，对于这些过程，GDC在多大程度上是强制性的还不清楚。本文报道了拟南芥（Arabidopsis thaliana）中两个基因编码的GDC亚基之一P蛋白的单个和组合T-DNA插入突变体的特征。单个敲除这两个基因中的任何一个都不会显著改变代谢和光合性能，这表明功能冗余。而在浓度为0.9% CO2的空气中，双突变体在子叶期后不发育。在这些非光呼吸条件下，莲座叶不会出现，幼苗的存活时间也不会超过3到4周。这一特征将缺乏GDC的双突变体与所有其他已知的光呼吸突变体区分开来，并为GDC在除光呼吸之外的重要代谢过程中不可替代的功能提供了证据。
The mitochondrial multienzyme glycine decarboxylase (GDC) catalyzes the tetrahydrofolate-dependent catabolism of glycine to 5,10-methylene-tetrahydrofolate and the side products NADH, CO 2, and NH3. This reaction forms part of the photorespiratory cycle and contributes to one-carbon metabolism. While the important role of GDC for these two metabolic pathways is well established, the existence of bypassing reactions has also been suggested. Therefore, it is not clear to what extent GDC is obligatory for these processes. Here, we report on features of individual and combined T-DNA insertion mutants for one of the GDC subunits, P protein, which is encoded by two genes in Arabidopsis (Arabidopsis thaliana). The individual knockout of either of these two genes does not significantly alter metabolism and photosynthetic performance indicating functional redundancy. In contrast, the double mutant does not develop beyond the cotyledon stage in air enriched with 0.9% CO2. Rosette leaves do not appear and the seedlings do not survive for longer than about 3 to 4 weeks under these nonphotorespiratory conditions. This feature distinguishes the GDC-lacking double mutant from all other known photorespiratory mutants and provides evidence for the nonreplaceable function of GDC in vital metabolic processes other than photorespiration.