A paradigm shift for the amino acid editing mechanism of human cytoplasmic leucyl-tRNA synthetase.
A paradigm shift for the amino acid editing mechanism of human cytoplasmic leucyl-tRNA synthetase.
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DOI：
10.1021/bi901111y
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发表时间：
2009-09-29
期刊：
影响因子：
2.9
通讯作者：
Martinis SA
中科院分区：
文献类型：
--
作者：
Pang YL;Martinis SA
亮基trna合成酶（LeuRS）已被确定为一类新型含硼小分子结合其编辑活性位点的靶标。当tRNALeu的3 '端与编辑活性位点结合时，硼与末端核糖的顺式二醇交联。交联rna -蛋白复合物阻断了酶的整体氨基酰化活性。与其他leurs类似，人细胞质酶（hscLeuRS）编辑活性位点位于一个称为结缔多肽1结构域（CP1）的离散结构域，在该结构域，错误带电的tRNA结合以水解非同源氨基酸。hscLeuRS的编辑位点包括高度保守的苏氨酸鉴别器和普遍保守的天冬氨酸，并进行了突变表征。将苏氨酸残基替换为与其他leurs类似的丙氨酸解偶联特异性。然而，在氨基酸结合口袋中引入大块残基未能阻止tRNA的去酰化，这表明氨基酸结合口袋的结构与其他表征的leurs不同。此外，普遍保守的天冬氨酸突变使tRNALeu去酰化失效。然而令人惊讶的是，这个编辑缺陷的hscLeuRS保持了保真度。在传输后编辑活动位点失败时，可能已经激活了备用编辑机制。
Leucyl-tRNA synthetase (LeuRS) has been identified as a target for a novel class of boron-containing small molecules that bind to its editing active site. When the 3′ end of tRNALeu binds to the editing active site, the boron crosslinks to the cis diols of its terminal ribose. The crosslinked RNA-protein complex blocks the overall aminoacylation activity of the enzyme. Similar to other LeuRSs, the human cytoplasmic enzyme (hscLeuRS) editing active site resides in a discrete domain called the connective polypeptide 1 domain (CP1), where mischarged tRNA binds for hydrolysis of the noncognate amino acid. The editing site of hscLeuRS includes a highly conserved threonine discriminator and universally conserved aspartic acid that were mutationally characterized. Substitution of the threonine residue to alanine uncoupled specificity similar to other LeuRSs. However, the introduction of bulky residues in the amino acid binding pocket failed to block deacylation of tRNA, indicating that the architecture of the amino acid binding pocket is different compared to other characterized LeuRSs. In addition, mutation of the universally conserved aspartic acid abolished tRNALeu deacylation. Surprisingly though, this editing-defective hscLeuRS maintained fidelity. It is possible that an alternate editing mechanism may have been activated upon failure of the post-transfer editing active site.
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影响因子：
8
作者：
Norcum, MT;Warrington, JA
通讯作者：
Warrington, JA
影响因子：
2.9
作者：
Betha, Aswini K.;Williams, Amy M.;Martinis, Susan A.
通讯作者：
Martinis, Susan A.
影响因子：
11.4
作者：
Cusack, S;Yaremchuk, A;Tukalo, M
通讯作者：
Tukalo, M
影响因子：
4.8
作者：
Hati, Sanchita;Ziervogel, Brigitte;Musier-Forsyth, Karin
通讯作者：
Musier-Forsyth, Karin
DOI：
10.1073/pnas.85.4.1033
发表时间：
1988-02-01
影响因子：
11.1
作者：
SAMPSON, JR;UHLENBECK, OC
通讯作者：
UHLENBECK, OC