Asymmetric maturation of a dimeric transfer RNA precursor.
Asymmetric maturation of a dimeric transfer RNA precursor.
复制标题
二聚体转移 RNA 前体的不对称成熟。
DOI：
10.1016/0022-2836(80)90135-7
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发表时间：
1980
影响因子：
5.6
通讯作者：
Scholla,CA
中科院分区：
文献类型：
--
作者：
Guthrie,C;Scholla,CA
噬菌体T4编码的8个转移rna中有6个是通过3个二聚体前体分子合成的。其中两个的序列已经确定。这两种前体在体内产生等量的同源tRNA分子。相比之下，即使在野生型感染中，trnaili的含量也不超过tRNAThr的30%，tRNAThr是由一种常见的二聚体前体加工而来。我们现在已经确定了这个二聚体的序列。除了tRNAThrand tRNAIle中存在的核苷酸外，它还含有9个前体特异性残基，位于5 ‘和3 ’端以及两个tRNA序列的间隙连接处。虽然这三种二聚体具有大多数共同的结构特征，但trnathr + ili是唯一在间隙区存在编码tRNA 3 ' -C-C-A末端的情况。这种二聚体在各种生物合成突变体中的处理已经在体内和体外进行了分析，并显示在几个方面是异常的。这些结果表明，trnaile的明显生产不足可以通过一种新的加工途径来解释，该途径产生代谢不稳定的trnaile产物。来自T4 tRNA基因簇的DNA序列分析数据（Fukada & Abelson, 1980）支持该前体的不对称成熟是-C-C-A序列独特配置的结果的结论。这些结果表明基因表达可以在RNA加工水平上被调节。这一现象的生物学意义与trnaile具有独特生理作用的证据有关。
Six of the eight transfer RNAs coded by bacteriophage T4 are synthesizedviathree dimeric precursor molecules. The sequences of two of these have been determined. Both of these precursors give rise to equimolar amounts of the cognate tRNA moleculesin vivo. In contrast, even in wild-type infections, tRNAIleis present in ≤ 30% the amount of tRNAThr, with which it is processed from a common dimeric precursor.We have now determined the sequence of this dimer. In addition to the nucleotides present in tRNAThrand tRNAIle, it contains nine precursor-specific residues, located at the 5′ and 3′ termini and at the interstitial junction of the two tRNA sequences. While the three dimers share the majority of structural features in common, pre-tRNAThr + Ileis the only case in which an encoded tRNA 3′ -C-C-A terminus is present in the interstitial region.The processing of this dimer in various biosynthetic mutants has been analyzedin vivoandin vitroand shown to be anomalous in several respects. These results suggest that the apparent underproduction of tRNAIlecan be explained by a novel processing pathway that generates a metabolically unstable tRNAIleproduct. Data from DNA sequence analysis of the T4 tRNA gene cluster (Fukada & Abelson, 1980) support the conclusion that the asymmetric maturation of this precursor is a consequence of the unique disposition of the -C-C-A sequence. These results argue that gene expression can be modulated at the level of RNA processing. The biological significance of this phenomenon is discussed in relation to evidence that tRNAIlehas a unique physiological role.