Recognition of tRNA(Cys) by Escherichia coli cysteinyl-tRNA synthetase.
Recognition of tRNA(Cys) by Escherichia coli cysteinyl-tRNA synthetase.
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大肠杆菌半胱氨酰-tRNA 合成酶对 tRNA(Cys) 的识别。
DOI：
10.1021/bi00080a014
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发表时间：
1993
期刊：
影响因子：
2.9
通讯作者：
Abelson,J
中科院分区：
文献类型：
--
作者：
Komatsoulis,GA;Abelson,J
1993年5月5日接收的修订版Mandarin pt摘要：使用体内和体外方法进行了大肠杆菌半胱氨酰-tRNA合成酶识别tRNACys的研究。所有三个反密码子核苷酸、第二核苷酸（73）和三级结构域中的一些元件（D茎/环、C茎/环和可变环）对于识别都很重要;反密码子茎和受体茎似乎不含必需元件。对应于tRNACys的T7 RNA聚合酶转录物仅是天然tRNACys的5.5倍差的底物（就特异性常数而言，k^/Km），主要是由于转录物的Km值增加。单核苷酸突变导致的最大特异性损失发生在突变后，根据取代的不同，k^ t/Km下降3-4个数量级。反密码子摆动核苷酸的突变也导致特异性常数降低3个数量级，而其他反密码子核苷酸的突变导致的影响较小。有趣的是，C35 A突变（苯丙氨酸反密码子GAA）对半胱氨酰-tRNA合成酶的氨酰化没有影响。几种琥珀抑制tRNA的构建，其体内特性与其体外特异性无关，这表明需要两种类型的实验来了解维持tRNA特异性的因素。基因准确地转化为蛋白质的物理表现形式，关键取决于翻译的保真度。翻译的准确性要求氨酰-tRNA合成酶在同源和非同源tRNA种类之间保持高度的区分。这种区分的挑战是巨大的，因为所有的tRNA似乎都具有一定程度的结构相似性，这可能是由于它们相互作用的要求。
Revised Manuscript Received May 5, 1993 abstract: A study of the recognition of tRNACys by Escherichia coli cysteinyl-tRNA synthetase using in vivo and in vitro methods was performed. All three anticodon nucleotides, the discriminator nucleotide (73), and some elements within the tertiary domain (the D stem/loop, the€ stem/loop, and the variable loop) are important for recognition; the anticodon stem and acceptor stem appear to contain no essential elements. A T7 RNA polymerase transcript correspondingto tRNACys is only a 5.5-fold worse substrate than native tRNACys (in terms of the specificity constant, k^/Km), mainly due to an increase in the value of Km for the transcript. The greatest loss of specificity caused by mutation of a single nucleotide occurs when the discriminator U7 3 is changed; k^ t/Km declines 3-4 orders of magnitude depending on the substitution. Mutations in thewobble nucleotide of the anticodon also cause reductions in the specificity constant of 3 orders of magnitude, while mutations in the other anticodon nucleotides causedlesser effects. Interestingly, a C35A mutation (with the phenylalanine anticodon GAA) had no effect on aminoacylation by the cysteinyl-tRNA synthetase. Several amber suppressor tRNAs were constructed whose in vivo identity didnot correlate with their in vitro specificity, indicating the need for both types of experiments to understand the factors which maintain tRNA specificity.The accurate conversion of genes into their physical manifestation as proteins is critically dependent upon the fidelity of translation. Translational accuracy requires that aminoacyl-tRNA synthetases maintain a high degree of discrimination between cognate and noncognate tRNA species. The challenge of such discrimination is formidable since all tRNAs appear to share a certain degree of structural similarity, presumably imposed by the requirement that they interact
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DOI：
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影响因子：
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DOI：
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发表时间：
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影响因子：
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作者：
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