Deletion of a conserved, central ribosomal intersubunit RNA bridge
Deletion of a conserved, central ribosomal intersubunit RNA bridge
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DOI：
10.1016/j.molcel.2006.08.011
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发表时间：
2006-09-15
期刊：
影响因子：
16
通讯作者：
Noller, Harry F.
中科院分区：
文献类型：
--
作者：
Ali, Iraj K.;Lancaster, Laura;Noller, Harry F.
核糖体结构的阐明激发了许多关于特定 rRNA 元件作用的提议，包括 23S rRNA 普遍保守的螺旋 69 (H69)，它形成亚基间桥 B2a 并接触 A 位点和 P 位点 tRNA 的 D 茎。 H69 不仅参与亚基关联和 tRNA 结合，还参与起始、易位、翻译准确性、肽基转移酶反应和核糖体回收。与这些建议一致，H69 的缺失赋予显性致死表型。值得注意的是，体外测定表明，亲和纯化的 Delta h69 核糖体具有正常的翻译准确性，从天然 mRNA 模板合成全长蛋白质，并支持野生型速率下的 EF-G 依赖性易位。然而，h Delta 69 50S 亚基在没有 tRNA 的情况下无法与 30S 亚基结合，在 RF1 催化的肽释放中存在缺陷，并且可以在没有 RRF 的情况下回收。
Elucidation of the structure of the ribosome has stimulated numerous proposals for the roles of specific rRNA elements, including the universally conserved helix 69 (H69) of 23S rRNA, which forms intersubunit bridge B2a and contacts the D stems of A- and P-site tRNAs. H69 has been proposed to be involved not only in subunit association and tRNA binding but also in initiation, translocation, translational accuracy, the peptidyl transferase reaction, and ribosome recycling. Consistent with such proposals, deletion of H69 confers a dominant lethal phenotype. Remarkably, in vitro assays show that affinity-purified Delta h69 ribosomes have normal translational accuracy, synthesize a full-length protein from a natural mRNA template, and support EF-G-dependent translocation at wild-type rates. However, h Delta 69 50S subunits are unable to associate with 30S subunits in the absence of tRNA, are defective in RF1-catalyzed peptide release, and can be recycled in the absence of RRF.