Extremely high intracellular concentration of glucose-6-phosphate and NAD(H) in Deinococcus radiodurans
Extremely high intracellular concentration of glucose-6-phosphate and NAD(H) in Deinococcus radiodurans
复制标题
耐辐射奇球菌细胞内葡萄糖-6-磷酸和 NAD(H) 浓度极高
DOI：
10.1007/s00792-016-0913-z
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发表时间：
2017
期刊：
影响因子：
2.9
通讯作者：
Shigeyuki Kawai
中科院分区：
文献类型：
--
作者：
Takumi Yamashiro;Kousaku Murata;Shigeyuki Kawai
耐辐射异常球菌对电离辐射和紫外线辐射以及由这些辐射引起的氧化应激具有高度抗性。NADP（H）似乎对于这种抗性是重要的（Slade和Radman，Microbiol Mol Biol Rev 75：133-191; Slade，Radman，Microbiol Mol Biol Rev 75：133-191，2011），但是在耐辐射杜氏酵母中NADP（H）或NAD（H）的产生的潜在机制尚未完全解决。细胞内NAD+、NADH、NADP+和NADPH的浓度也尚未确定。我们发现D.放射性同位素标记的NAD（P）+还原表明D.抗辐射细胞含有酶和高浓度的这种活性的底物。该酶和底物是葡萄糖-6-磷酸脱氢酶和葡萄糖-6-磷酸，其细胞内浓度极高。出乎意料的是，细胞内NAD（H）的浓度也远大于NADP（H）的浓度，表明NADH的一些重要作用。这种细菌的这些不寻常的特征将揭示这种细菌生理学的一个新方面。
Deinococcus radioduransis highly resistant to ionizing radiation and UV radiation, and oxidative stress caused by such radiations. NADP(H) seems to be important for this resistance (Slade and Radman, Microbiol Mol Biol Rev 75:133–191; Slade, Radman, Microbiol Mol Biol Rev 75:133–191, 2011), but the mechanism underlying the generation of NADP(H) or NAD(H) inD. radioduranshas not fully been addressed. Intracellular concentrations of NAD+, NADH, NADP+, and NADPH inD. radioduransare also not determined yet. We found that cell extracts ofD. radioduranscatalyzed reduction of NAD(P)+in vitro, indicating thatD. radioduranscells contain both enzymes and a high concentration of substrates for this activity. The enzyme and the substrate were attributed to glucose-6-phosphate dehydrogenase and glucose-6-phosphate of which intracellular concentration was extremely high. Unexpectedly, the intracellular concentration of NAD(H) was also much greater than that of NADP(H), suggesting some significant roles of NADH. These unusual features of this bacterium would shed light on a new aspect of physiology of this bacterium.