Alternative tertiary structure of tRNA for recognition by a posttranscriptional modification enzyme
Alternative tertiary structure of tRNA for recognition by a posttranscriptional modification enzyme
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DOI：
10.1016/s0092-8674(03)00280-0
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发表时间：
2003-05-02
期刊：
影响因子：
64.5
通讯作者：
Yokoyama, S
中科院分区：
文献类型：
--
作者：
Ishitani, R;Nureki, O;Yokoyama, S
转移RNA （tRNA）通常具有三叶草二级结构，受体、D臂、反密码子和T臂折叠成l形三级结构。为了加强L型，转录后修饰发生在核心内的核苷酸上，但修饰酶在L型中是矛盾的。在本研究中，我们测定了与古苷tRNA-鸟嘌呤转糖基化酶结合的tRNA的晶体结构，该酶修饰了核心D臂的G15。结合的tRNA具有与L型截然不同的另一种构象（“λ型”）。所有的d臂二级碱基对和规范的三级相互作用都被破坏。此外，一个螺旋结构被重组，而D臂的其余部分是单链和突出。因此，该酶通过计算从G1到G15的λ形式的核苷酸数，精确地定位暴露在活性位点的G15。
Transfer RNA (tRNA) canonically has the clover-leaf secondary structure with the acceptor, D, anticodon, and T arms, which are folded into the L-shaped tertiary structure. To strengthen the L form, posttranscriptional modifications occur on nucleotides buried within the core, but the modification enzymes are paradoxically inaccessible to them in the L form. In this study, we determined the crystal structure of tRNA bound with archaeosine tRNA-guanine transglycosylase, which modifies G15 of the D arm in the core. The bound tRNA assumes an alternative conformation ("lambda form") drastically different from the L form. All of the D-arm secondary base pairs and the canonical tertiary interactions are disrupted. Furthermore, a helical structure is reorganized, while the rest of the D arm is single stranded and protruded. Consequently, the enzyme precisely locates the exposed G15 in the active site, by counting the nucleotide number from G1 to G15 in the lambda form.