Isolated CP1 domain of Escherichia coli leucyl-tRNA synthetase is dependent on flanking hinge motifs for amino acid editing activity
Isolated CP1 domain of Escherichia coli leucyl-tRNA synthetase is dependent on flanking hinge motifs for amino acid editing activity
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DOI：
10.1021/bi061965j
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发表时间：
2007-05-29
期刊：
影响因子：
2.9
通讯作者：
Martinis, Susan A.
中科院分区：
文献类型：
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作者：
Betha, Aswini K.;Williams, Amy M.;Martinis, Susan A.
蛋白质合成及其保真度依赖于氨酰-tRNA合成酶。亮氨酰-tRNA合成酶（LeuRS）、异亮氨酰-tRNA合成酶（IleRS）和缬氨酰-tRNA合成酶（ValRS）已经进化出称为CP 1的离散编辑结构域，其水解相应的错误氨酰化的非同源氨基酸。虽然已经分离出IleRS和ValRS的活性CP 1结构域片段，但先前的报告表明LeuRS CP 1结构域需要特异质适应以赋予独立于全长酶的编辑活性。在本文中，一系列合理设计的大肠杆菌LeuRS片段的表征表明，连接CP 1结构域与LeuRS的氨酰化核心的β-链是编辑错误电荷的tRNA（Leu）所必需的。水解活性也通过在两条LeuRS β链末端包含被称为“铰链”的短柔性肽而增强。我们提出，这些长的β链延伸的LeuRS CP 1结构域相互作用的tRNA特异性转移后编辑的misaminoacylated氨基酸。
Protein synthesis and its fidelity rely upon the aminoacyl-tRNA synthetases. Leucyl-tRNA synthetase (LeuRS), isoleucyl-tRNA synthetase (IleRS), and valyl-tRNA synthetase (ValRS) have evolved a discrete editing domain called CP1 that hydrolyzes the respective incorrectly misaminoacylated noncognate amino acids. Although active CP1 domain fragments have been isolated for IleRS and ValRS, previous reports suggested that the LeuRS CP1 domain required idiosyncratic adaptations to confer editing activity independent of the full-length enzyme. Herein, characterization of a series of rationally designed Escherichia coli LeuRS fragments showed that the beta-strands, which link the CP1 domain to the aminoacylation core of LeuRS, are required for editing of mischarged tRNA(Leu). Hydrolytic activity was also enhanced by inclusion of short flexible peptides that have been called "hinges" at the end of both LeuRS beta-strands. We propose that these long beta-strand extensions of the LeuRS CP1 domain interact specifically with the tRNA for post-transfer editing of misaminoacylated amino acids.