THE EXCHANGE OF THE DISCRIMINATOR BASE A73 FOR G IS ALONE SUFFICIENT TO CONVERT HUMAN TRNA(LEU) INTO A SERINE-ACCEPTOR IN-VITRO
THE EXCHANGE OF THE DISCRIMINATOR BASE A73 FOR G IS ALONE SUFFICIENT TO CONVERT HUMAN TRNA(LEU) INTO A SERINE-ACCEPTOR IN-VITRO
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DOI：
10.1002/j.1460-2075.1994.tb06615.x
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发表时间：
1994-07-01
期刊：
影响因子：
11.4
通讯作者：
GROSS, HJ
中科院分区：
文献类型：
--
作者：
BREITSCHOPF, K;GROSS, HJ
转移RNA（tRNA）的同一性是通过几个定义的核苷酸或核苷酸组（称为同一性元件）与同源氨酰-tRNA合成酶的高度特异性相互作用以及与其他19种氨酰-tRNA合成酶的非生产性相互作用来维持的。大多数tRNA在至少两个位置上有一组身份元件，通常在反密码子环或受体茎中，以及在第73位碱基。我们已经使用T7 RNA聚合酶转录的tRNA来证明，用tRNA（Ser）特异性G对人tRNA（Leu）的碱基A73的唯一替换产生了对丝氨酸接受的完全身份转换。相反的实验，人tRNA（Ser）中的G73交换为tRNA（Leu）特异性A，导致丝氨酸特异性的完全丧失，而不产生任何亮氨酸接受。这些结果表明，人tRNA的丝氨酸碱基A73（Leu）单独保护该tRNA免受丝氨酰-tRNA合成酶的丝氨酰化。这是第一次报告的一个完整的身份转换所造成的交换单基地。
Transfer RNA (tRNA) identity is maintained by the highly specific interaction of a few defined nucleotides or groups of nucleotides, called identity elements, with the cognate aminoacyl-tRNA synthetase, and by nonproductive interactions with the other 19 aminoacyl-tRNA synthetases. Most tRNAs have a set of identity elements in at least two locations, commonly in the anticodon loop or in the acceptor stem, and at the discriminator base position 73. We have used T7 RNA polymerase transcribed tRNAs to demonstrate that the sole replacement of the discriminator base A73 of human tRNA(Leu) with the tRNA(Ser)-specific G generates a complete identity switch to serine acceptance. The reverse experiment, the exchange of G73 in human tRNA(Ser) for the tRNA(Leu)-specific A, causes a total loss of serine specificity without creating any leucine acceptance. These results suggest that the discriminator base A73 of human tRNA(Leu) alone protects this tRNA against serylation by seryl-tRNA synthetase. This is the first report of a complete identity switch caused by an exchange of the discriminator base alone.