A recurrent magnesium-binding motif provides a framework for the ribosomal peptidyl transferase center.
A recurrent magnesium-binding motif provides a framework for the ribosomal peptidyl transferase center.
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DOI：
10.1093/nar/gkp119
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发表时间：
2009-06
影响因子：
14.9
通讯作者：
Williams LD
中科院分区：
文献类型：
--
作者：
Hsiao C;Williams LD
核糖体是一种古老的大分子机器，负责合成所有生物体内的所有蛋白质。在这里，我们证明了核糖体肽转移酶中心(Ptc)是由镁微团簇(mg2+-μc‘s)支撑的。镁离子-μc的共同特征包括两个成对的镁离子，它们被一个共同的桥联磷酸基团以Mg(A)2+-(O1P-P-O2P)-Mg(B)2+的形式螯合。这种桥联磷酸盐是Mg(a)2+–(OP-P-O5′-C5′-C4′-C3′-O3′-P-OP)–Mg(a)2+.形式的10元螯合环的一部分这个10元环的两个磷酸基团是由RNA骨架上相邻的残基贡献的。这两个镁离子都是八面体配位的，但由于与额外的RNA磷酸基团相互作用而基本上脱水。LSU(大亚基)中的镁离子-μc‘s在进化过程中似乎是高度保守的，因为它们在细菌(Thermus thermophilus，pdb条目2J01)和古菌(Haloarcula marismortui，pdb条目1JJ2)中没有变化。由Mg~(2+)-μc‘s连接的23S rRNA的2D元件在细菌、古生菌和真核生物的rRNA之间和线粒体rRNA中以及在一个建议的最小23S-rRNA中是保守的。我们在其他RNA中观察到镁离子-μc‘s，包括细菌的16SRRNA和四膜虫I组内含子核酶的P4-P6结构域。这表明，镁离子-核糖核酸c‘s是一个原始基序，在μ折叠、功能和进化中起着关键作用。
The ribosome is an ancient macromolecular machine responsible for the synthesis of all proteins in all living organisms. Here we demonstrate that the ribosomal peptidyl transferase center (PTC) is supported by a framework of magnesium microclusters (Mg2+-μc's). Common features of Mg2+-μc's include two paired Mg2+ ions that are chelated by a common bridging phosphate group in the form Mg(a)2+–(O1P-P-O2P)–Mg(b)2+. This bridging phosphate is part of a 10-membered chelation ring in the form Mg(a)2+–(OP-P-O5′-C5′-C4′-C3′-O3′-P-OP)–Mg(a)2+. The two phosphate groups of this 10-membered ring are contributed by adjacent residues along the RNA backbone. Both Mg2+ ions are octahedrally coordinated, but are substantially dehydrated by interactions with additional RNA phosphate groups. The Mg2+-μc's in the LSU (large subunit) appear to be highly conserved over evolution, since they are unchanged in bacteria (Thermus thermophilus, PDB entry 2J01) and archaea (Haloarcula marismortui, PDB entry 1JJ2). The 2D elements of the 23S rRNA that are linked by Mg2+-μc's are conserved between the rRNAs of bacteria, archaea and eukarya and in mitochondrial rRNA, and in a proposed minimal 23S-rRNA. We observe Mg2+-μc's in other rRNAs including the bacterial 16S rRNA, and the P4–P6 domain of the tetrahymena Group I intron ribozyme. It appears that Mg2+-μc's are a primeval motif, with pivotal roles in RNA folding, function and evolution.