Mechanisms of the tRNA wobble cytidine modification essential for AUA codon decoding in prokaryotes
Mechanisms of the tRNA wobble cytidine modification essential for AUA codon decoding in prokaryotes
复制标题
原核生物 AUA 密码子解码所必需的 tRNA 摆动胞苷修饰机制
DOI：
10.1080/09168451.2014.975185
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Tomoyuki Numata
中科院分区：
文献类型：
--
作者：
Kashiwagi Kazuhiro;Takuhiro Ito;and Shigeyuki Yokoyama;Tomoyuki Numata
细菌和古细菌在AUA密码子特异性tRNAIle的反密码子的第一个（摆动）位置分别具有2-赖氨酰胞苷（L或lysidine）和2-胍丁胺基胞苷（agm 2C或agmatidine）。这些赖氨酸或胍基丁胺结合的胞苷衍生物对于精确解码遗传密码至关重要。L是由tRNA赖氨酸合成酶（TilS）以L-赖氨酸和ATP为底物合成的。Agm 2C的形成由tRNAIle-agm 2C合成酶（TiaS）催化，其使用胍丁胺和ATP进行反应。尽管TilS和TiaS合成结构相似的胞苷衍生物，但这些酶属于非相关蛋白质家族。因此，这些酶通过不同的催化机制修饰摆动胞苷，其中TilS通过腺苷酸化激活摆动胞苷的C2碳，而TiaS通过磷酸化激活摆动胞苷。相比之下，TilS和TiaS具有相似的tRNA识别机制，其中酶识别tRNA受体茎以区分tRNAIle和tRNAMet。
Bacteria and archaea have 2-lysylcytidine (L or lysidine) and 2-agmatinylcytidine (agm2C or agmatidine), respectively, at the first (wobble) position of the anticodon of the AUA codon-specific tRNAIle. These lysine- or agmatine-conjugated cytidine derivatives are crucial for the precise decoding of the genetic code. L is synthesized by tRNAIle-lysidine synthetase (TilS), which usesl-lysine and ATP as substrates. Agm2C formation is catalyzed by tRNAIle-agm2C synthetase (TiaS), which uses agmatine and ATP for the reaction. Despite the fact that TilS and TiaS synthesize structurally similar cytidine derivatives, these enzymes belong to non-related protein families. Therefore, these enzymes modify the wobble cytidine by distinct catalytic mechanisms, in which TilS activates the C2 carbon of the wobble cytidine by adenylation, while TiaS activates it by phosphorylation. In contrast, TilS and TiaS share similar tRNA recognition mechanisms, in which the enzymes recognize the tRNA acceptor stem to discriminate tRNAIleand tRNAMet.