Ribosomal Protein L11 Selectively Stabilizes a Tertiary Structure of the GTPase Center rRNA Domain.
Ribosomal Protein L11 Selectively Stabilizes a Tertiary Structure of the GTPase Center rRNA Domain.
复制标题
核糖体蛋白 L11 选择性地稳定 GTP 酶中心 rRNA 结构域的三级结构。
DOI：
10.1016/j.jmb.2019.12.010
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发表时间：
2020
影响因子：
5.6
通讯作者：
Hall,KathleenB
中科院分区：
文献类型：
--
作者：
Welty,Robb;Rau,Michael;Pabit,Suzette;Dunstan,MarkS;Conn,GraemeL;Pollack,Lois;Hall,KathleenB
细菌 23S rRNA 中的 GTP 酶中心 (GAC) RNA 结构域直接与核糖体蛋白 L11 结合，该复合物对于核糖体功能至关重要。先前与 L11 结合的 58 核苷酸 GAC RNA 的共晶结构揭示了 RNA 结构域的复杂三级折叠，其中一个一价离子和几个二价离子位于结构内的特定位点。在这里，我们报告了游离 GAC 的新晶体结构，该结构与 L11 结合结构基本相同，保留了许多常见的二价离子占据位点。这种新结构表明，RNA 单独折叠成与结合的二价离子的三级结构。在解决方案中，我们发现这种三级结构不是静态的，而是最好将其描述为状态的集合。虽然 L11 蛋白在 RNA 采用其三级结构之前无法与 GAC 结合，但新的实验数据表明 L11 与 Mg2+ 依赖性折叠状态结合，我们认为这种折叠状态位于 RNA 的折叠途径中。我们认为 L11 稳定了特定的 GAC RNA 三级态，对应于晶体结构，并且该结构反映了完全组装的核糖体中 rRNA 结构域的功能关键构象。
The GTPase Center (GAC) RNA domain in bacterial 23S rRNA is directly bound by ribosomal protein L11, and this complex is essential to ribosome function. Previous cocrystal structures of the 58-nucleotide GAC RNA bound to L11 revealed the intricate tertiary fold of the RNA domain, with one monovalent and several divalent ions located in specific sites within the structure. Here, we report a new crystal structure of the free GAC that is essentially identical to the L11-bound structure, which retains many common sites of divalent ion occupation. This new structure demonstrates that RNA alone folds into its tertiary structure with bound divalent ions. In solution, we find that this tertiary structure is not static, but rather is best described as an ensemble of states. While L11 protein cannot bind to the GAC until the RNA has adopted its tertiary structure, new experimental data show that L11 binds to Mg2+-dependent folded states, which we suggest lie along the folding pathway of the RNA. We propose that L11 stabilizes a specific GAC RNA tertiary state, corresponding to the crystal structure, and that this structure reflects the functionally critical conformation of the rRNA domain in the fully assembled ribosome.