The contribution of metal ions to the structural stability of the large ribosomal subunit
The contribution of metal ions to the structural stability of the large ribosomal subunit
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DOI：
10.1261/rna.7390804
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发表时间：
2004-09-01
期刊：
影响因子：
4.5
通讯作者：
Steitz, TA
中科院分区：
文献类型：
--
作者：
Klein, DJ;Moore, PB;Steitz, TA
众所周知，一价阳离子和镁离子对于形成复杂和紧凑结构的大RNA分子的折叠和稳定性至关重要。在海盐蚌核糖体大亚基的原子结构中，我们已经确定了116个镁离子和88个主要与rRNA结合的单价阳离子。虽然这些金属离子结合的rRNA结构是高度特异的，但从协调它们的特定官能团的身份中已经出现了一些共同的原则。磷酸基团的非桥氧是Mg++最常见的内壳配体，并且具有一个或两个这样的内壳配体的Mg++离子是非常常见的。非桥磷酸氧和核苷酸碱基的杂原子是Mg++离子的常见外壳配体。一价阳离子通常与核苷酸碱基和蛋白质基团相互作用，尽管也发现了一些与非桥磷酸氧的相互作用。最常见的一价阳离子结合位点是G-U摆动对的大沟侧。二价和一价阳离子通过介导其结构域之间的相互作用来稳定23 S rRNA的三级结构。结合的金属离子在肽基转移酶中心周围的区域中特别丰富，其中核糖体蛋白的稳定阳离子尾明显不存在。这可能表明，在蛋白质出现之前的进化时期，金属离子对于稳定特定RNA结构的重要性，因此这些金属离子结合位点中的许多可能在所有系统发育王国中是保守的。
Both monovalent cations and magnesium ions are well known to be essential for the folding and stability of large RNA molecules that form complex and compact structures. In the atomic structure of the large ribosomal subunit from Haloarcula marismortui, we have identified 116 magnesium ions and 88 monovalent cations bound principally to rRNA. Although the rRNA structures to which these metal ions bind are highly idiosyncratic, a few common principles have emerged from the identities of the specific functional groups that coordinate them. The nonbridging oxygen of a phosphate group is the most common inner shell ligand of Mg++, and Mg++ ions having one or two such inner shell ligands are very common. Nonbridging phosphate oxygens and the heteroatoms of nucleotide bases are common outer shell ligands for Mg++ ions. Monovalent cations usually interact with nucleotide bases and protein groups, although some interactions with nonbridging phosphate oxygens are found. The most common monovalent cation binding site is the major groove side of G-U wobble pairs. Both divalent and monovalent cations stabilize the tertiary structure of 23S rRNA by mediating interactions between its structural domains. Bound metal ions are particularly abundant in the region surrounding the peptidyl transferase center, where stabilizing cationic tails of ribosomal proteins are notably absent. This may point to the importance of metal ions for the stabilization of specific RNA structures in the evolutionary period prior to the appearance of proteins, and hence many of these metal ion binding sites may be conserved across all phylogenetic kingdoms.