The AAA-ATPase MIDASIN 1 Functions in Ribosome Biogenesis and Is Essential for Embryo and Root Development
The AAA-ATPase MIDASIN 1 Functions in Ribosome Biogenesis and Is Essential for Embryo and Root Development
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AAA-ATPase MIDASIN 1 在核糖体生物发生中发挥作用，对于胚胎和根发育至关重要
DOI：
10.1104/pp.18.01225
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发表时间：
2019-05-01
期刊：
影响因子：
7.4
通讯作者：
Wang, Xing-Jun
中科院分区：
文献类型：
--
作者：
Li, Peng-Cheng;Li, Ke;Wang, Xing-Jun
核糖体生物合成是一个精心策划的过程，依赖于许多组装因素。 AAA-ATPase Midasin 1 (Mdn1) 在酵母（酿酒酵母）中充当核糖体组装因子，但 MDN1 在拟南芥（Arabidopsis thaliana）中的作用知之甚少。在这里，我们证明 MDN1 的拟南芥无效突变体是胚胎致死的。使用维持活力的弱突变体mdn1-1，我们发现MDN1对于球状胚中生长素最大值的规则模式以及根分生组织维持的功能至关重要。通过检测核糖体蛋白的亚细胞分布，我们注意到 mdn1-1 会损害 60S 前核糖体颗粒的核输出。核糖体前体 RNA（包括 35S、27SB 和 20S）的加工也在该突变体中受到影响。 MDN1 与 PESCADILLO2 (PES2) 发生物理相互作用，PESCADILLO2 (PES2) 是 60S 核糖体的重要组装因子，并且观察到 PES2 在 mdn1-1 中的错误定位进一步表明 MDN1 在 60S 核糖体生物发生中发挥着不可或缺的作用。因此，观察到的 mdn1-1 对真核翻译抑制剂和高糖条件的超敏性可能与核糖体生物合成的缺陷有关。总体而言，这项工作确立了拟南芥 MDN1 在核糖体生物发生中的作用，这与其在胚胎发生和根发育中的作用一致。
Ribosome biogenesis is an orchestrated process that relies on many assembly factors. The AAA-ATPase Midasin 1 (Mdn1) functions as a ribosome assembly factor in yeast (Saccharomyces cerevisiae), but the roles of MDN1 in Arabidopsis (Arabidopsis thaliana) are poorly understood. Here, we showed that the Arabidopsis null mutant of MDN1 is embryo-lethal. Using the weak mutant mdn1-1, which maintains viability, we found that MDN1 is critical for the regular pattern of auxin maxima in the globular embryo and functions in root meristem maintenance. By detecting the subcellular distribution of ribosome proteins, we noted that mdn1-1 impairs nuclear export of the pre-60S ribosomal particle. The processing of ribosomal precusor RNAs, including 35S, 27SB, and 20S, is also affected in this mutant. MDN1 physically interacts with PESCADILLO2 (PES2), an essential assembly factor of the 60S ribosome, and the observed mislocalization of PES2 in mdn1-1 further implied that MDN1 plays an indispensable role in 60S ribosome biogenesis. Therefore, the observed hypersensitivity of mdn1-1 to a eukaryotic translation inhibitor and high-sugar conditions might be associated with the defect in ribosome biogenesis. Overall, this work establishes a role of Arabidopsis MDN1 in ribosome biogenesis, which agrees with its roles in embryogenesis and root development.