A Novel Mechanism for Nitrosative Stress Tolerance Dependent on GTP Cyclohydrolase II Activity Involved in Riboflavin Synthesis of Yeast
A Novel Mechanism for Nitrosative Stress Tolerance Dependent on GTP Cyclohydrolase II Activity Involved in Riboflavin Synthesis of Yeast
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DOI：
10.1038/s41598-020-62890-3
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发表时间：
2020-04-07
影响因子：
4.6
通讯作者：
Takagi, Hiroshi
中科院分区：
文献类型：
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作者：
Anam, Khairul;Nasuno, Ryo;Takagi, Hiroshi
一氧化氮（NO）的生物学功能取决于其浓度，过量的NO会导致各种有害的情况，称为亚硝化应激。因此，生物体具有多种策略来调节细胞内NO浓度和/或解毒过量的NO。在这里，我们使用遗传筛选，以确定一种新的亚硝化胁迫耐受基因，RIB 1，编码GTP环化水解酶II（GTPCH 2），催化核黄素生物合成的第一步。我们进一步的分析表明，Rib 1的GTPCH 2酶活性是RIB 1依赖性亚硝化应激耐受性所必需的，但核黄素本身并不是这种耐受性所必需的。此外，重组纯化Rib 1的反应混合物显示出淬灭NO或其衍生物，即使Rib 1反应的副产物甲酸盐或焦磷酸盐不淬灭NO或其衍生物，这表明Rib 1的反应产物2，5-二氨基-6-（5-磷酸-D-核糖基氨基）-嘧啶-4（3 H）-酮（DARP）清除NO或其衍生物。最后，发现与DARP的嘧啶部分相同的2，4，5-三氨基-1H-嘧啶-6-酮清除NO或其衍生物，表明DARP与经由其嘧啶部分产生的N2 O3反应。
The biological functions of nitric oxide (NO) depend on its concentration, and excessive levels of NO induce various harmful situations known as nitrosative stress. Therefore, organisms possess many kinds of strategies to regulate the intracellular NO concentration and/or to detoxify excess NO. Here, we used genetic screening to identify a novel nitrosative stress tolerance gene, RIB1, encoding GTP cyclohydrolase II (GTPCH2), which catalyzes the first step in riboflavin biosynthesis. Our further analyses demonstrated that the GTPCH2 enzymatic activity of Rib1 is essential for RIB1-dependent nitrosative stress tolerance, but that riboflavin itself is not required for this tolerance. Furthermore, the reaction mixture of a recombinant purified Rib1 was shown to quench NO or its derivatives, even though formate or pyrophosphate, which are byproducts of the Rib1 reaction, did not, suggesting that the reaction product of Rib1, 2,5-diamino-6-(5-phospo-D-ribosylamino)-pyrimidin-4(3 H)-one (DARP), scavenges NO or its derivatives. Finally, it was revealed that 2,4,5-triamino-1H-pyrimidin-6-one, which is identical to a pyrimidine moiety of DARP, scavenged NO or its derivatives, suggesting that DARP reacts with N2O3 generated via its pyrimidine moiety.