Residues in a class I tRNA synthetase which determine selectivity of amino acid recognition in the context of tRNA.
Residues in a class I tRNA synthetase which determine selectivity of amino acid recognition in the context of tRNA.
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DOI：
10.1021/bi00035a028
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发表时间：
1995-09
期刊：
影响因子：
2.9
通讯作者：
Eric F. Schmidt;Paul Schimmel
中科院分区：
文献类型：
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作者：
Eric F. Schmidt;Paul Schimmel
某些氨酰-tRNA合成酶通过在其同源tRNA存在下的水解编辑反应来区分非常相似的氨基酸。一个例子是I类异亮氨酰-tRNA合成酶。我们最近表明，在初始氨基酸结合和活化步骤中消除异亮氨酸（Ile）和缬氨酸（瓦尔）之间的区别的突变对在异亮氨酸tRNA（tRNA（Ile））存在下活化的缬氨酸的水解编辑几乎没有影响。结果表明，初始的氨基酸结合和歧视是功能独立的tRNA依赖的氨基酸歧视。在这项工作中，我们交联（异亮氨酰-tRNA合成酶）的反应类似物的缬氨酸misacylated到tRNA（Ile）。通过交联分析鉴定的肽段内特定残基的突变严重影响Val-tRNA（Ile）与Ile-tRNA（Ile）的区分。突变敏感残基是插入催化结构域的一部分，并且它们本身在酶的所有已知原核和真核序列中完全保守。
Certain aminoacyl-tRNA synthetases discriminate between closely similar amino acids by hydrolytic editing reactions in the presence of their cognate tRNA. An example is the class I isoleucyl-tRNA synthetase. We recently showed that a mutation which eliminates discrimination between isoleucine (Ile) and valine (Val) in the initial amino acid binding and activation steps had little effect on the hydrolytic editing of activated valine in the presence of isoleucine tRNA (tRNA(Ile)). The results showed that initial amino acid binding and discrimination are functionally independent of tRNA-dependent amino acid discrimination. In this work, we cross-linked (to isoleucyl-tRNA synthetase) a reactive analog of valine misacylated onto tRNA(Ile). Mutation of specific residues within a peptide segment identified by the cross-linking analysis severely affected discrimination of Val-tRNA(Ile) versus Ile-tRNA(Ile). The mutationally sensitive residues are part of an insertion into the catalytic domain and are themselves completely conserved among all known prokaryotic and eukaryotic sequences of the enzyme.