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Ribosomal Protein L11 Selectively Stabilizes a Tertiary Structure of the GTPase Center rRNA Domain.
Journal of Molecular Biology ( IF 4.7 ) Pub Date : 2019-12-24 , DOI: 10.1016/j.jmb.2019.12.010
Robb Welty 1 , Michael Rau 2 , Suzette Pabit 3 , Mark S Dunstan 4 , Graeme L Conn 5 , Lois Pollack 3 , Kathleen B Hall 2
Affiliation  

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.

中文翻译:

核糖体蛋白L11选择性稳定GTPase中心rRNA结构域的三级结构。

细菌23S rRNA中的GTPase Center(GAC)RNA结构域直接与核糖体蛋白L11结合,这种复合物对于核糖体功能至关重要。与L11结合的58个核苷酸的GAC RNA的先前共晶体结构揭示了RNA结构域的复杂三级折叠,其中一个单价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,该结构基本上与L11结合的结构相同,该结构保留了许多常见的二价离子占据位点。这种新结构表明,RNA单独与结合的二价离子折叠成其三级结构。在解决方案中,我们发现此三级结构不是静态的,而是最好描述为状态的整体。尽管L11蛋白只有在RNA采纳其三级结构后才能与GAC结合,但新的实验数据表明L11与Mg2 +依赖的折叠状态结合,我们建议其位于RNA的折叠路径上。我们建议L11稳定特定的GAC RNA叔状态,对应于晶体结构,并且该结构反映了在完全组装的核糖体中rRNA结构域的功能关键性构象。
更新日期:2019-12-25
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