The mitochondrial thioredoxin system regulates the TCA cycle-derived metabolic fluxes toward the GS/GOGAT cycle in illuminated leaves.

IF 5.6 2区 生物学 Q1 PLANT SCIENCES
Paulo V L Souza, Vicente T C B Alencar, Humaira Bahadar, Joaquim Albenisio G Silveira, Danilo M Daloso
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引用次数: 0

Abstract

Previous studies suggest that the synthesis of glutamate/glutamine is regulated by the mitochondrial thioredoxin (TRX) system. However, the mechanisms behind it remains unclear. Here, we demonstrated that the level of citrate and glutamate was higher in illuminated leaves from Arabidopsis mutants lacking the mitochondrial TRX o1 (trxo1) or both NADPH-dependent TRX reductases A/B (ntrab), that are found in nucleus, cytosol and mitochondria, when compared to the wild type (WT). Increased 13C-labelling in glutamate derived from 13C-pyruvate was observed in illuminated trxo1 and ntrab leaves, but not in WT and in the microsomal trxh2 mutant. The lack of TRX o1 decreased the content and activity of glutamine synthetase (GS), which leads to a lower level of glutamine, and exacerbated the increases in GS activity triggered by high light, when compared to the WT. The level of glutamine was positively correlated with the percentage of the oxidized GS band. However, the GS redox status was unaltered in all mutants. Our results indicate mitochondrial TRX mutants have higher metabolic fluxes from the TCA to the GS/GOGAT cycle in vivo, likely associated to an increased substrate availability and by direct-and-indirect TRX-mediated mechanisms that regulate enzymes of both TCA and GS/GOGAT cycles.

线粒体硫氧还蛋白系统调节光照叶片中TCA循环衍生的GS/GOGAT循环代谢通量。
先前的研究表明,谷氨酸/谷氨酰胺的合成受线粒体硫氧还蛋白(TRX)系统的调节。然而,其背后的机制尚不清楚。在这里,我们证明了与野生型(WT)相比,在缺乏线粒体TRX o1 (trxo1)或nadph依赖性TRX还原酶A/B (ntrab)的拟南芥突变体的光照叶片中,柠檬酸盐和谷氨酸的水平更高,这些酶存在于细胞核、细胞质和线粒体中。13c -丙酮酸衍生的谷氨酸的13c标记在trx1和ntrab叶片中观察到增加,但在WT和微体trxh2突变体中没有。TRX o1缺失导致谷氨酰胺合成酶(GS)含量和活性降低,导致谷氨酰胺水平降低,并加剧了强光触发的GS活性升高,与WT相比,谷氨酰胺水平与GS氧化带百分比呈正相关。然而,在所有突变体中,GS氧化还原状态没有改变。我们的研究结果表明,线粒体TRX突变体在体内从TCA到GS/GOGAT循环的代谢通量更高,这可能与底物利用率的增加以及TRX介导的直接和间接机制有关,该机制调节TCA和GS/GOGAT循环的酶。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Journal of Experimental Botany
Journal of Experimental Botany 生物-植物科学
CiteScore
12.30
自引率
4.30%
发文量
450
审稿时长
1.9 months
期刊介绍: The Journal of Experimental Botany publishes high-quality primary research and review papers in the plant sciences. These papers cover a range of disciplines from molecular and cellular physiology and biochemistry through whole plant physiology to community physiology. Full-length primary papers should contribute to our understanding of how plants develop and function, and should provide new insights into biological processes. The journal will not publish purely descriptive papers or papers that report a well-known process in a species in which the process has not been identified previously. Articles should be concise and generally limited to 10 printed pages.
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