Jank Thomas, Belyi Yury, Wirth Christophe, Rospert Sabine, Hu Zehan, Dengjel Jörn, Tzivelekidis Tina, Andersen Gregers Rom, Hunte Carola, Schlosser Andreas, Aktories Klaus
From the Institute for Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany,
the Gamaleya Research Centre, Moscow 123098, Russia.
J Biol Chem. 2017 Sep 29;292(39):16014-16023. doi: 10.1074/jbc.M117.801035. Epub 2017 Aug 11.
Ribosomal translation factors are fundamental for protein synthesis and highly conserved in all kingdoms of life. The essential eukaryotic elongation factor 1A (eEF1A) delivers aminoacyl tRNAs to the A-site of the translating 80S ribosome. Several studies have revealed that eEF1A is posttranslationally modified. Using MS analysis, site-directed mutagenesis, and X-ray structural data analysis of eEF1A, we identified a posttranslational modification in which the α amino group of mono-l-glutamine is covalently linked to the side chain of glutamate 45 in eEF1A. The MS analysis suggested that all eEF1A molecules are modified by this glutaminylation and that this posttranslational modification occurs at all stages of yeast growth. The mutational studies revealed that this glutaminylation is not essential for the normal functions of eEF1A in However, eEF1A glutaminylation slightly reduced growth under antibiotic-induced translational stress conditions. Moreover, we identified the same posttranslational modification in eEF1A from but not in various other eukaryotic organisms tested despite strict conservation of the Glu residue among these organisms. We therefore conclude that eEF1A glutaminylation is a yeast-specific posttranslational modification that appears to influence protein translation.
核糖体翻译因子是蛋白质合成所必需的，在所有生命王国中都高度保守。必需的真核延伸因子1A（eEF1A）将氨酰基tRNA转运到正在翻译的80S核糖体的A位点。多项研究表明，eEF1A存在翻译后修饰。通过对eEF1A进行质谱分析、定点诱变和X射线结构数据分析，我们鉴定出一种翻译后修饰，即单L-谷氨酰胺的α氨基与eEF1A中谷氨酸45的侧链共价连接。质谱分析表明，所有eEF1A分子都被这种谷氨酰胺化修饰，且这种翻译后修饰发生在酵母生长的各个阶段。突变研究表明，这种谷氨酰胺化对于eEF1A在酵母中的正常功能并非必不可少。然而，在抗生素诱导的翻译应激条件下，eEF1A的谷氨酰胺化会轻微降低酵母的生长速度。此外，我们在酿酒酵母的eEF1A中鉴定出了相同的翻译后修饰，但在测试的其他各种真核生物中未发现，尽管这些生物中Glu残基严格保守。因此，我们得出结论，eEF1A的谷氨酰胺化是一种酵母特异性的翻译后修饰，似乎会影响蛋白质翻译。
