Agmatine-conjugated cytidine in a tRNA anticodon is essential for AUA decoding in archaea
Agmatine-conjugated cytidine in a tRNA anticodon is essential for AUA decoding in archaea
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DOI：
10.1038/nchembio.323
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发表时间：
2010-04-01
影响因子：
14.8
通讯作者：
Suzuki, Tsutomu
中科院分区：
文献类型：
--
作者：
Ikeuchi, Yoshiho;Kimura, Satoshi;Suzuki, Tsutomu
一些 tRNA 反密码子的第一个（摆动）位置的碱基修饰对于破译遗传密码至关重要。在真核生物和真细菌中，AUA 密码子由分别带有修饰碱基假尿苷（和/或肌苷）和赖氨酸的 tRNA（Ile）解码。古菌物种翻译 AUA 密码子的机制尚不清楚。我们描述了位于古菌 tRNA(Ile) 摆动位置的多胺缀合修饰碱基 2-agmatinylcytidine（agm(2)C 或 agmatidine），可特异性解码 AUA 密码子。我们证明古菌细胞使用胍丁胺合成 tRNA(Ile) 的 agm(2)C。我们还鉴定了一种新酶 tRNA(Ile)-agm(2)C 合成酶 (TiaS)，它在胍丁胺和 ATP 存在的情况下催化 agm(2)C 形成。尽管 agm2C 在化学上与赖氨酸相似，但 TiaS 构成了与 tRNA(Ile)-赖氨酸合成酶 (TilS) 不同的一类酶，这表明解码系统跨域趋同进化。
A modified base at the first (wobble) position of some tRNA anticodons is critical for deciphering the genetic code. In eukaryotes and eubacteria, AUA codons are decoded by tRNAs(Ile) with modified bases pseudouridine (and/or inosine) and lysidine, respectively. The mechanism by which archaeal species translate AUA codons is unclear. We describe a polyamine-conjugated modified base, 2-agmatinylcytidine (agm(2)C or agmatidine), at the wobble position of archaeal tRNA(Ile) that decodes AUA codons specifically. We demonstrate that archaeal cells use agmatine to synthesize agm(2)C of tRNA(Ile). We also identified a new enzyme, tRNA(Ile)-agm(2)C synthetase (TiaS), that catalyzes agm(2)C formation in the presence of agmatine and ATP. Although agm2C is chemically similar to lysidine, TiaS constitutes a distinct class of enzyme from tRNA(Ile)-lysidine synthetase (TilS), suggesting that the decoding systems evolved convergently across domains.