Resuming translation on tmRNA: a unique mode of determining a reading frame
Resuming translation on tmRNA: a unique mode of determining a reading frame
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DOI：
10.1093/emboj/18.19.5423
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发表时间：
1999-10-01
期刊：
影响因子：
11.4
通讯作者：
Bartel, DP
中科院分区：
文献类型：
--
作者：
Williams, KP;Martindale, KA;Bartel, DP
细菌核糖体从缺少框内终止密码子的mRNA转换，并在称为tmRNA、SsrA或10 Sa RNA的专门RNA上恢复翻译。我们发现，核糖体可以达到和使用的极端3'末端密码子的缺陷mRNA之前转换。在两个水平上确定在tmRNA中翻译的第一个三联体（恢复密码子）：tmRNA中的远端元件将恢复密码子的选择限制在狭窄的窗口内，而本地上游元件提供精确度。从随机选择实验中获得的见解确保了来自不同物种的tmRNA序列的比对。三联体UA（A/G）（通常被释放因子-1识别为终止密码子）在恢复密码子上游的两个核苷酸处高度保守，该三联体的中心腺苷对于tmRNA活性是必需的。tmRNA的阅读框架与所有其他已知的阅读框架不同，因为第一个翻译密码子不是由特定的tRNA反密码子指定的。
The bacterial ribosome switches from an mRNA lacking an in-frame stop codon and resumes translation on a specialized RNA known as tmRNA, SsrA or 10Sa RNA. We find that the ribosome can reach and use the extreme 3' terminal codon of the defective mRNA prior to switching. The first triplet to be translated in tmRNA (the resume codon) is determined at two levels: distant elements in tmRNA restrict resume codon choice to a narrow window and local upstream elements provide precision. Insights from a randomization-selection experiment secure the alignment of tmRNA sequences from diverse species. The triplet UA(A/G) (normally recognized as a stop codon by release factor-1) is strongly conserved two nucleotides upstream of the resume codon, The central adenosine of this triplet is essential for tmRNA activity. The reading frame of tmRNA is determined differently from all other known reading frames in that the first translated codon is not specified by a particular tRNA anticodon.