Structural basis of tRNA agmatinylation essential for AUA codon decoding
Structural basis of tRNA agmatinylation essential for AUA codon decoding
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DOI：
10.1038/nsmb.2144
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发表时间：
2011-11-01
影响因子：
16.8
通讯作者：
Numata, Tomoyuki
中科院分区：
文献类型：
--
作者：
Osawa, Takuo;Kimura, Satoshi;Numata, Tomoyuki
AUA密码子特异性古细菌tRNA（Ile 2）中反密码子（C34）第一位的胞苷被修饰为2-胍丁胺基胞苷（agm（2）C或agmatidine），这是一种胍丁胺缀合的胞苷衍生物，对于遗传密码的精确解码至关重要。Agm（2）C由tRNA（Ile）-agm（2）C合成酶（TiaS）以ATP依赖性方式合成。在这里，我们提出了与ATP，或与AMPCPP和胍丁胺复合的闪烁古生球菌TiaS-tRNA（Ile 2）的晶体结构，揭示了一个以前未知的激酶模块所需的激活C34磷酸化，并显示TiaS区分tRNA（Ile 2）和tRNA（Met）的分子机制。在TiaS-tRNA（Ile 2）-ATP复合物中，C34被捕获在远离ATP结合位点的口袋中。在含胍丁胺的晶体中，C34位于激酶模块中的AMPCPP γ-磷酸附近，表明胍丁胺对于将C34置于活性位点是必需的。这些观测也提供了agm（2）C形成的结构动力学。
The cytidine at the first position of the anticodon (C34) in the AUA codon-specific archaeal tRNA(Ile2) is modified to 2-agmatinylcytidine (agm(2)C or agmatidine), an agmatine-conjugated cytidine derivative, which is crucial for the precise decoding of the genetic code. Agm(2)C is synthesized by tRNA(Ile)-agm(2)C synthetase (TiaS) in an ATP-dependent manner. Here we present the crystal structures of the Archaeoglobus fulgidus TiaS-tRNA(Ile2) complexed with ATP, or with AMPCPP and agmatine, revealing a previously unknown kinase module required for activating C34 by phosphorylation, and showing the molecular mechanism by which TiaS discriminates between tRNA(Ile2) and tRNA(Met). In the TiaS-tRNA(Ile2)-ATP complex, C34 is trapped within a pocket far away from the ATP-binding site. In the agmatine-containing crystals, C34 is located near the AMPCPP gamma-phosphate in the kinase module, demonstrating that agmatine is essential for placing C34 in the active site. These observations also provide the structural dynamics for agm(2)C formation.