N-terminal acetylation (Nt-acetylation) is one of the most common protein modifications in eukaryotes. The function of Naa50, the catalytic subunit of the evolutionarily conserved N-terminal acetyltransferase (Nat) E complex, has not been reported in Arabidopsis. In this study, we found that a loss of Naa50 resulted in a pleiotropic phenotype that included dwarfism and sterility, premature leaf senescence and a shortened primary root. Further analysis revealed that root cell patterning and various root cell properties were severely impaired in naa50 mutant plants. Moreover, defects in auxin distribution were observed due to the mislocalization of PIN auxin transporters. In contrast to its homologs in yeast and animals, Naa50 showed no co-immunoprecipitation with any subunit of the Nat A complex. Moreover, plants lacking Naa50 displayed hypersensitivity to abscisic acid and osmotic stress. Therefore, our results suggest that protein N-terminal acetylation catalyzed by Naa50 plays an essential role in Arabidopsis growth and osmotic stress responses.

中文翻译：

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N末端乙酰转移酶Naa50调节拟南芥的生长和渗透胁迫反应。

N-末端乙酰化（Nt-乙酰化）是真核生物中最常见的蛋白质修饰之一。Naa50的功能，在进化上保守的N末端乙酰转移酶（Nat）E复杂的催化亚基，尚未在拟南芥中报道。在这项研究中，我们发现失去Naa50会导致多效性表型，包括矮化和不育，叶片过早衰老和缩短的初生根。进一步的分析表明，naa50严重破坏了根细胞模式和各种根细胞特性突变植物。此外，由于PIN生长素转运蛋白的定位错误，观察到了生长素分布的缺陷。与它在酵母和动物中的同系物相比，Naa50没有与Nat A复合物的任何亚基共免疫沉淀。此外，缺乏Naa50的植物对脱落酸和渗透胁迫表现出超敏性。因此，我们的结果表明，Naa50催化的蛋白N末端乙酰化在拟南芥生长和渗透胁迫响应中起着至关重要的作用。