Glutamate, Ornithine, Arginine, Proline, and Polyamine Metabolic Interactions: The Pathway Is Regulated at the Post-Transcriptional Level.
Glutamate, Ornithine, Arginine, Proline, and Polyamine Metabolic Interactions: The Pathway Is Regulated at the Post-Transcriptional Level.
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DOI：
10.3389/fpls.2016.00078
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发表时间：
2016
影响因子：
5.6
通讯作者：
Minocha SC
中科院分区：
文献类型：
--
作者：
Majumdar R;Barchi B;Turlapati SA;Gagne M;Minocha R;Long S;Minocha SC
谷氨酸代谢为鸟氨酸、精氨酸、脯氨酸和多胺是植物氮代谢途径的主要网络，它还产生一氧化氮和γ-氨基丁酸（GABA）等中间体，在植物发育和胁迫中起重要作用。虽然该网络的中间体和产物的积累主要依赖于氮同化，但相互作用的子通路的总体调控尚不清楚。我们验证了鸟氨酸转移到多胺生物合成（通过转基因方法）的假设，不仅在调节其自身的谷氨酸生物合成中起作用，而且还影响精氨酸和脯氨酸的生物合成。利用2个高腐胺产系（含转基因小鼠鸟氨酸脱羧酶基因），研究了：(1)外源碳氮供给对拟南芥多胺和可溶性氨基酸库的影响；(2)精氨酸、脯氨酸和GABA生物合成及多胺分解代谢相互作用通路关键酶基因的表达。研究结果表明：(1)谷氨酸向精氨酸和多胺的整体转化通过转基因产物中鸟氨酸对多胺生物合成的利用而增强；(2)脯氨酸和精氨酸的生物合成独立于多胺和GABA的生物合成；(3)尽管谷氨酸合成氨基丁酸的总量增加了数倍，但大多数编码精氨酸和GABA生物合成相互作用亚通路酶的基因（共28个）的表达并未发生变化；(4)增加的多胺生物合成导致细胞对氮和碳的同化增加。
The metabolism of glutamate into ornithine, arginine, proline, and polyamines is a major network of nitrogen-metabolizing pathways in plants, which also produces intermediates like nitric oxide, and γ-aminobutyric acid (GABA) that play critical roles in plant development and stress. While the accumulations of intermediates and the products of this network depend primarily on nitrogen assimilation, the overall regulation of the interacting sub-pathways is not well understood. We tested the hypothesis that diversion of ornithine into polyamine biosynthesis (by transgenic approach) not only plays a role in regulating its own biosynthesis from glutamate but also affects arginine and proline biosynthesis. Using two high putrescine producing lines of Arabidopsis thaliana (containing a transgenic mouse ornithine decarboxylase gene), we studied the: (1) effects of exogenous supply of carbon and nitrogen on polyamines and pools of soluble amino acids; and, (2) expression of genes encoding key enzymes in the interactive pathways of arginine, proline and GABA biosynthesis as well as the catabolism of polyamines. Our findings suggest that: (1) the overall conversion of glutamate to arginine and polyamines is enhanced by increased utilization of ornithine for polyamine biosynthesis by the transgene product; (2) proline and arginine biosynthesis are regulated independently of polyamines and GABA biosynthesis; (3) the expression of most genes (28 that were studied) that encode enzymes of the interacting sub-pathways of arginine and GABA biosynthesis does not change even though overall biosynthesis of Orn from glutamate is increased several fold; and (4) increased polyamine biosynthesis results in increased assimilation of both nitrogen and carbon by the cells.