Dph3, a small protein required for diphthamide biosynthesis, is essential in mouse development
Dph3, a small protein required for diphthamide biosynthesis, is essential in mouse development
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DOI：
10.1128/mcb.26.10.3835-3841.2006
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发表时间：
2006-05-01
影响因子：
5.3
通讯作者：
Leppla, Stephen H.
中科院分区：
文献类型：
--
作者：
Liu, Shihui;Wiggins, Jason F.;Leppla, Stephen H.
真核生物中的翻译延伸因子2（eEF-2）含有一个独特的后修饰组氨酸残基，称为白喉酰胺，其作为白喉毒素和铜绿假单胞菌外毒素A的唯一靶标。二苯二甲酰胺的生物合成是由五个高度保守的蛋白质，Dph 1至Dph 5，和一个尚未确定的酰胺化酶。复杂的双苯二甲酰胺生物合成途径在整个真核生物中的进化保守性意味着双苯二甲酰胺在正常细胞生理学中的关键作用。在合成邻苯二甲酰胺所需的蛋白质中，Dph 3是最小的，仅含有82个残基。除了在二苯二甲酰胺生物合成中起作用外，Dph 3还参与调节酵母中的延伸子复合物的功能。为了探索Dph 3的生理作用并开始研究联苯二胺的功能，我们产生了dph 3敲除小鼠，并显示dph 3（+/-）小鼠是表型正常的，而dph 3（-/-）小鼠，其在eEF-2上缺乏联苯二胺修饰，是胚胎致死的。dph 3两个等位基因的缺失导致胚胎发育普遍延迟，伴随着尿囊与绒毛膜融合的缺乏和神经管变性和坏死的增加，并且与超过胚胎11.5天的生命不相容。dph 3（-/-）胎盘也发育异常，表现为较薄的迷路，缺乏胚胎红细胞和血管。这些结果证明了Dph 3在发育中的生理重要性。本文还讨论了Dph 3的生物学作用。
The translation elongation factor 2 in eukaryotes (eEF-2) contains a unique posttranslationally modified histidine residue, termed diphthamide, which serves as the only target for diphtheria toxin and Pseudomonas aeruginosa exotoxin A. Diphthamide biosynthesis is carried out by five highly conserved proteins, Dph1 to Dph5, and an as-yet-unidentified amidating enzyme. The evolutionary conservation of the complex diphthamide biosynthesis pathway throughout eukaryotes implies a key role for diphthamide in normal cellular physiology. Of the proteins required for diphthamide synthesis, Dph3 is the smallest, containing only 82 residues. In addition to having a role in diphthamide biosynthesis, Dph3 is also involved in modulating the functions of the Elongator complex in yeast. To explore the physiological roles of Dph3 and to begin to investigate the function of diphthamide, we generated dph3 knockout mice and showed that dph3(+/-) mice are phenotypically normal, whereas dph3(-/-) mice, which lack the diphthamide modification on eEF-2, are embryonic lethal. Loss of both dph3 alleles causes a general delay in embryonic development accompanied by lack of allantois fusion to the chorion and increased degeneration and necrosis in neural tubes and is not compatible with life beyond embryonic day 11.5. The dph3(-/-) placentas also developed abnormally, showing a thinner labyrinth lacking embryonic erythrocytes and blood vessels. These results attest to the physiological importance of Dph3 in development. The biological roles of Dph3 are also discussed.