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首页> 外文期刊>Journal of Molecular Biology >On the Mechanism and Origin of Isoleucyl-tRNA Synthetase Editing against Norvaline
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On the Mechanism and Origin of Isoleucyl-tRNA Synthetase Editing against Norvaline

机译：对诺韦伐氏菌脱孔-TrNA合成酶编辑的机制及起源

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Aminoacyl-tRNA synthetases (aaRSs), the enzymes responsible for coupling tRNAs to their cognate amino acids, minimize translational errors by intrinsic hydrolytic editing. Here, we compared norvaline (Nva), a linear amino acid not coded for protein synthesis, to the proteinogenic, branched valine (Val) in their propensity to mistranslate isoleucine (Ile) in proteins. We show that in the synthetic site of isoleucyl-tRNA synthetase (IleRS), Nva and Val are activated and transferred to tRNA at similar rates. The efficiency of the synthetic site in pre-transfer editing of Nva and Val also appears to be similar. Post-transfer editing was, however, more rapid with Nva and consequently IleRS misaminoacylates Nva-tRNA(Ile) at slower rate than Val-tRNA(Ile). Accordingly, an Escherichia coli strain lacking IleRS post-transfer editing misincorporated Nva and Val in the proteome to a similar extent and at the same Ile positions. However, Nva mistranslation inflicted higher toxicity than Val, in agreement with IleRS editing being optimized for hydrolysis of Nva-tRNA(Ile). Furthermore, we found that the evolutionary-related IleRS, leucyl- and valyl-tRNA synthetases (I/L/VRSs), all efficiently hydrolyze Nva-tRNAs even when editing of Nva seems redundant. We thus hypothesize that editing of Nva-tRNAs had already existed in the last common ancestor of I/L/VRSs, and that the editing domain of I/L/VRSs had primarily evolved to prevent infiltration of Nva into modern proteins. (C) 2019 Elsevier Ltd. All rights reserved.
机译：氨基酰基-TRNA合成酶（AARS），负责将TRNA与其同源氨基酸偶联的酶，最大限度地通过固有的水解编辑最小化平移误差。在此，我们将诺甲酸盐（NVA）进行比较，未编码蛋白质合成的线性氨基酸，以蛋白质化，支链缬氨酸（VAL）以蛋白质中的递增替代的蛋白质（ILE）。我们表明，在异孔-TrNA合成酶（ILELES）的合成位点，NVA和VAL以相似的速率激活并转移至TRNA。合成站点在NVA和Val的预传递编辑中的效率也似乎是相似的。然而，转移后编辑与NVA更快，因此ILERS以比VAL-TRNA（ILE）更慢的速率在较慢的速率下释放NVA-TRNA（ILE）。因此，缺乏ILERS的大肠杆菌菌株在蛋白质组中转移后转移的MISIND掺入的NVA和VAL在相似的程度和相同的ILE位置。然而，NVA isranslation与val的毒性造成更高的毒性，同意ILERS编辑被针对水解NVA-TRNA（ILE）进行了优化。此外，我们发现进化相关的ILERE，白胶和缬氨酸-TRNA合成酶（I / L / VRS），即使在NVA的编辑似乎是多余的时，也能够有效地水解NVA-TRNA。因此，我们假设NVA-TRNA的编辑已经存在于I / L / VRSS的最后一个常见的祖先中，并且I / L / VRSS的编辑结构域主要进化以防止NVA渗入现代蛋白质。 （c）2019 Elsevier Ltd.保留所有权利。

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