Structure of the most conserved internal loop in SRP RNA
Structure of the most conserved internal loop in SRP RNA
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DOI：
10.1038/10683
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发表时间：
1999-07-01
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影响因子：
--
通讯作者：
Walter, P
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文献类型：
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作者：
Schmitz, U;James, TL;Walter, P
信号识别颗粒（SRP）引导核糖体翻译至内质网（ER）膜或细菌质膜的蛋白质易位装置。 SRP 普遍保守，在原核生物中由两个必需亚基组成：SRP RNA 和 SRP54，后者与新生蛋白链上的信号序列结合。在这里，我们描述了 28 聚体 RNA 的溶液 NMR 结构，该 RNA 构成了 SRP54 结合的 SRP RNA 最保守的部分。该功能的核心是一个六核苷酸内部环，它呈现出一种新颖的 Mg2+ 依赖性结构，具有不寻常的跨链相互作用；除了跨链 A/A 堆叠外，两个鸟嘌呤还与相反链的磷酸盐形成氢键，该结构完全解释了环碱基的系统发育保守性，强调了其对 SRP54 结合和 SRP 功能的重要性。
The signal recognition particle (SRP) directs translating ribosomes to the protein translocation apparatus of endoplasmic reticulum (ER) membrane or the bacterial plasma membrane. The SRP is universally conserved, and in prokaryotes consists of two essential subunits, SRP RNA and SRP54, the latter of which binds to signal sequences on the nascent protein chains. Here we describe the solution NMR structure of a 28-mer RNA composing the most conserved part of SRP RNA to which SRP54 binds. Central to this function is a six-nucleotide internal loop that assumes a novel Mg2+-dependent structure with unusual cross-strand interactions; besides a cross-strand A/A stack, two guanines form hydrogen bonds with opposite-strand phosphates, The structure completely explains the phylogenetic conservation of the loop bases, underlining its importance for SRP54 binding and SRP function.