One integral step in the transition from a nucleic acid encoded-genome to functional proteins is the aminoacylation of tRNA molecules. To perform this activity, aminoacyl-tRNA synthetases (aaRSs) activate free amino acids in the cell forming an aminoacyl-adenylate before transferring the amino acid on to its cognate tRNA. These newly formed aminoacyl-tRNA (aa-tRNA) can then be used by the ribosome during mRNA decoding. In Escherichia coli, there are twenty aaRSs encoded in the genome, each of which corresponds to one of the twenty proteinogenic amino acids used in translation. Given the shared chemicophysical properties of many amino acids, aaRSs have evolved mechanisms to prevent erroneous aa-tRNA formation with non-cognate amino acid substrates. Of particular interest is the post-transfer proofreading activity of alanyl-tRNA synthetase (AlaRS) which prevents the accumulation of Ser-tRNAAla and Gly-tRNAAla in the cell. We have previously shown that defects in AlaRS proofreading of Ser-tRNAAla lead to global dysregulation of the E. coli proteome, subsequently causing defects in growth, motility, and antibiotic sensitivity. Here we report second-site AlaRS suppressor mutations that alleviate the aforementioned phenotypes, revealing previously uncharacterized residues within the AlaRS proofreading domain that function in quality control.

中文翻译：

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丙氨酰-tRNA 合成酶质量控制的微调减轻了蛋白质组的全球失调

从核酸编码的基因组到功能性蛋白质的过渡过程中一个不可或缺的步骤是 tRNA 分子的氨酰化。为了执行此活动，氨酰-tRNA 合成酶 (aaRS) 激活细胞中的游离氨基酸，形成氨酰-腺苷酸，然后将氨基酸转移到其同源 tRNA 上。这些新形成的氨酰-tRNA (aa-tRNA) 然后可以在 mRNA 解码过程中被核糖体使用。在大肠杆菌中，基因组中编码了 20 个 aaRS，每个都对应于翻译中使用的 20 个蛋白氨基酸之一。鉴于许多氨基酸具有共同的化学物理特性，aaRS 已经进化出机制来防止与非同源氨基酸底物形成错误的 aa-tRNA。特别令人感兴趣的是丙氨酰-tRNA 合成酶 (AlaRS) 的转移后校对活性，它可以防止 Ser-tRNAAla 和 Gly-tRNAAla 在细胞中的积累。我们之前已经表明，Ser-tRNAAla 的 AlaRS 校对缺陷会导致大肠杆菌蛋白质组的整体失调，随后导致生长、运动和抗生素敏感性方面的缺陷。在这里，我们报告了减轻上述表型的第二位 AlaRS 抑制突变，揭示了 AlaRS 校对域内在质量控制中起作用的先前未表征的残基。和抗生素敏感性。在这里，我们报告了减轻上述表型的第二位 AlaRS 抑制突变，揭示了 AlaRS 校对域内在质量控制中起作用的先前未表征的残基。和抗生素敏感性。在这里，我们报告了减轻上述表型的第二位 AlaRS 抑制突变，揭示了 AlaRS 校对域内在质量控制中起作用的先前未表征的残基。