AN UNUSUAL RNA TERTIARY INTERACTION HAS A ROLE FOR THE SPECIFIC AMINOACYLATION OF A TRANSFER-RNA
AN UNUSUAL RNA TERTIARY INTERACTION HAS A ROLE FOR THE SPECIFIC AMINOACYLATION OF A TRANSFER-RNA
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DOI：
10.1073/pnas.90.14.6776
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发表时间：
1993-07-15
影响因子：
11.1
通讯作者：
GIEGE, R
中科院分区：
文献类型：
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作者：
HOU, YM;WESTHOF, E;GIEGE, R
已发现 tRNA 中与同源氨酰基-tRNA 合成酶特异性相互作用的核苷酸主要位于螺旋茎、反密码子或鉴别碱基中，其中不同的 tRNA 的核苷酸有所不同。负责 tRNA 三级结构的保守和半保守核苷酸已被证明在合成酶识别中作用不大。在这里，我们报道大肠杆菌 tRNA(Cys) 的氨酰化取决于反密码子、鉴别碱基以及 15 和 48 位半保守核苷酸之间的三级相互作用。虽然所有其他 tRNA 在 15 位含有嘌呤，在 48 位含有互补嘧啶，建立了称为 Levitt 对的三级相互作用，但大肠杆菌 tRNA(Cys)有鸟苷-15和-48。用胞苷替换鸟苷-15或-48实际上消除了氨酰化。化学探针的结构分析表明，鸟苷-15和-48通过环外N-2和环N-3之间的氢键相互作用，以稳定tRNA的两个长螺旋茎的连接。这种三级相互作用不同于莱维特对中传统的碱基配对方案，其中N-1和O-6之间会形成氢键。我们的结果为 RNA 三级结构在合成酶识别中的作用提供了证据。
The nucleotides in a tRNA that specifically interact with the cognate aminoacyl-tRNA synthetase have been found largely located in the helical stems, the anticodon, or the discriminator base, where they vary from one tRNA to another. The conserved and semiconserved nucleotides that are responsible for the tRNA tertiary structure have been shown to have little role in synthetase recognition. Here we report that aminoacylation of Escherichia coli tRNA(Cys) depends on the anticodon, the discriminator base, and a tertiary interaction between the semiconserved nucleotides at positions 15 and 48. While all other tRNAs contain a purine at position 15 and a complementary pyrimidine at position 48 that establish the tertiary interaction known as the Levitt pair, E. coli tRNA(Cys) has guanosine -15 and -48. Replacement of guanosine -15 or -48 with cytidine virtually eliminates aminoacylation. Structural analyses with chemical probes suggest that guanosine -15 and -48 interact through hydrogen bonds between the exocyclic N-2 and ring N-3 to stabilize the joining of the two long helical stems of the tRNA. This tertiary interaction is different from the traditional base pairing scheme in the Levitt pair, where hydrogen bonds would form between N-1 and O-6. Our results provide evidence for a role of RNA tertiary structure in synthetase recognition.