Physiological functions of pyruvate:NADP+ oxidoreductase and 2-oxoglutarate decarboxylase in Euglena gracilis under aerobic and anaerobic conditions
Physiological functions of pyruvate:NADP+ oxidoreductase and 2-oxoglutarate decarboxylase in Euglena gracilis under aerobic and anaerobic conditions
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DOI：
10.1080/09168451.2017.1318696
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发表时间：
2017-01-01
影响因子：
1.6
通讯作者：
Miyatake, Kazutaka
中科院分区：
文献类型：
--
作者：
Nakazawa, Masami;Hayashi, Ryuta;Miyatake, Kazutaka
在绿叶草中，除了丙酮酸脱氢酶复合物外，丙酮酸：NADP（+）氧化还原酶在线粒体中起丙酮酸氧化脱羧的作用。此外，2-氧戊二酸脱氢酶复合物不存在，相反，在线粒体中发现了2-氧戊二酸脱羧酶。为了阐明绿藻在好氧和厌氧条件下的核心碳和能量代谢，我们通过基因沉默实验研究了这些参与2-氧酸代谢的酶的生理意义。丙酮酸脱氢酶复合体是葡萄糖培养基中需氧细胞生长所必需的，尽管其活性低于丙酮酸：NADP（+）氧化还原酶的1%。相反，丙酮酸：NADP（+）氧化还原酶只参与厌氧能量代谢（蜡酯发酵）。当2-氧戊二酸脱羧酶基因被沉默时，好氧细胞的生长几乎被完全抑制，这表明绿藻的三羧酸循环被修饰，2-氧戊二酸脱羧酶取代了2-氧戊二酸脱氢酶复合物在好氧呼吸代谢中的作用。
In Euglena gracilis, pyruvate:NADP(+) oxidoreductase, in addition to the pyruvate dehydrogenase complex, functions for the oxidative decarboxylation of pyruvate in the mitochondria. Furthermore, the 2-oxoglutarate dehydrogenase complex is absent, and instead 2-oxoglutarate decarboxylase is found in the mitochondria. To elucidate the central carbon and energy metabolisms in Euglena under aerobic and anaerobic conditions, physiological significances of these enzymes involved in 2-oxoacid metabolism were examined by gene silencing experiments. The pyruvate dehydrogenase complex was indispensable for aerobic cell growth in a glucose medium, although its activity was less than 1% of that of pyruvate:NADP(+) oxidoreductase. In contrast, pyruvate:NADP(+) oxidoreductase was only involved in the anaerobic energy metabolism (wax ester fermentation). Aerobic cell growth was almost completely suppressed when the 2-oxoglutarate decarboxylase gene was silenced, suggesting that the tricarboxylic acid cycle is modified in Euglena and 2-oxoglutarate decarboxylase takes the place of the 2-oxoglutarate dehydrogenase complex in the aerobic respiratory metabolism.