Decoding the biosynthesis and function of diphthamide, an enigmatic modification of translation elongation factor 2 (EF2).
Decoding the biosynthesis and function of diphthamide, an enigmatic modification of translation elongation factor 2 (EF2).
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DOI：
10.15698/mic2014.06.151
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发表时间：
2014-05-20
期刊：
影响因子：
--
通讯作者：
Stark MJ
中科院分区：
文献类型：
--
作者：
Schaffrath R;Stark MJ
二苯二甲酰胺是古细菌和真核翻译延伸因子2（EF 2）的高度保守修饰，但为什么细胞需要EF 2含有二苯二甲酰胺还不清楚。在酵母中，合成二苯二甲酰胺的第一步和形成中间体白喉所需的基因（DPH 1-DPH 5）有充分的文献记载。然而，最后一步，酰胺化的diphthine到diphthamide，在很大程度上是不明确的。值得注意的是，通过挖掘全基因组合成基因阵列（SGA）和化学基因组学数据库，Uthman等人[PLoS Genetics（2013）9，e1003334]和Su等人[Proc.Natl. Acad. Sci. USA（2012）109，19983-19987]已经鉴定了另外两种联苯二酰胺作用物，DPH 6和DPH 7。与酰胺化步骤中的作用一致，dph 6和dph 7缺失菌株不能完成白喉合成并积累白喉修饰的EF 2。与催化相关的酰胺酶Dph 6相反，Dph 7似乎是调节性的。如Uthman等人所示，它促进白喉合酶（Dph 5）与EF 2的解离，允许发生Dph 6的白喉酰胺化，从而将白喉合成偶联到途径中的末端步骤。值得注意的是，Uthman等人的研究表明，Dph 5作为EF 2抑制剂具有新的作用，当diphthamide合成被阻断或不完全时，Dph 5会影响细胞生长，重要的是，Dph 5表明diphthamide在翻译过程中促进EF 2性能的准确性。
Diphthamide is a highly conserved modification of archaeal and eukaryal translation elongation factor 2 (EF2) and yet why cells need EF2 to contain diphthamide is unclear. In yeast, the first steps of diphthamide synthesis and the genes (DPH1-DPH5) required to form the intermediate diphthine are well-documented. However, the last step, amidation of diphthine to diphthamide, had largely been ill-defined. Remarkably, through mining genome-wide synthetic gene array (SGA) and chemical genomics databases, recent studies by Uthman et al. [PLoS Genetics (2013) 9, e1003334] and Su et al. [Proc. Natl. Acad. Sci. USA (2012) 109, 19983-19987] have identified two more diphthamide players, DPH6 and DPH7. Consistent with roles in the amidation step, dph6 and dph7 deletion strains fail to complete diphthamide synthesis and accumulate diphthine-modified EF2. In contrast to Dph6, the catalytically relevant amidase, Dph7 appears to be regulatory. As shown by Uthman et al., it promotes dissociation of diphthine synthase (Dph5) from EF2, allowing diphthine amidation by Dph6 to occur and thereby coupling diphthine synthesis to the terminal step in the pathway. Remarkably, the study by Uthman et al. suggests that Dph5 has a novel role as an EF2 inhibitor that affects cell growth when diphthamide synthesis is blocked or incomplete and, importantly, shows that diphthamide promotes the accuracy of EF2 performance during translation.