The three-dimensional structures of two complexes between recombinant MS2 capsids and RNA operator fragments reveal sequence-specific protein-RNA interactions
The three-dimensional structures of two complexes between recombinant MS2 capsids and RNA operator fragments reveal sequence-specific protein-RNA interactions
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DOI：
10.1006/jmbi.1997.1144
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发表时间：
1997-08-01
影响因子：
5.6
通讯作者：
Liljas, L
中科院分区：
文献类型：
--
作者：
Valegard, K;Murray, JB;Liljas, L
在2.7埃分辨率下测定了两个重组MS2衣壳与RNA操纵子片段的络合物的晶体结构。RNA噬菌体MS2的外壳蛋白具有双功能；它形成二十面体病毒壳来保护病毒核酸，并通过与RNA上唯一的位置高度特异性地结合作为翻译抑制物，这是一个单一的茎环结构，包含病毒复制酶基因的起始密码子。为了确定这些蛋白质-RNA复合体的结构，我们使用了化学合成的茎环片段的变体，并将它们浸泡在重组衣壳的晶体中。RNA茎环与蛋白质结合，形成新月形结构，并与外壳蛋白二聚体的β-折叠表面相互作用。它使蛋白质与茎环51侧的七个磷酸基团接触，在位置-5的嘧啶碱基堆积在酪氨酸上，并与两个暴露的腺嘌呤碱基接触，一个在环中，一个在茎的凸起处。在-5位用胞嘧啶取代野生型尿苷显著增加了RNA对二聚体的亲和力。在该位置含有胞嘧啶的RNA茎环复合体与野生型复合体的不同之处在于，主要是多了一个分子内RNA相互作用和一个额外的水介导的氢键。(C)1997年学术出版社有限公司。
Crystal structures of two complexes between recombinant MS2 capsids and RNA operator fragments have been determined at 2.7 Angstrom resolution. The coat protein of the RNA bacteriophage MS2 is bifunctional; it forms the icosahedral virus shell to protect the viral nucleic acid and it acts as a translational repressor by binding with high specificity to a unique site on the RNA, a single stem-loop structure, containing the initiation codon of the gene for the viral replicase. Tn order to determine the structure of these protein-RNA complexes, we have used chemically synthesized variants of the stem-loop fragment and soaked them into crystals of recombinant capsids. The RNA stem-loop, as bound to the protein, forms a crescent-like structure and interacts with the surface of the beta-sheet of a coat protein dimer. It makes protein contacts with seven phosphate groups on the 51 side of the stem-loop, with a pyrimidine base at position -5, which stacks onto a tyrosine, and with two exposed adenine bases, one in the loop and one at a bulge in the stem. Replacement of the wild-type uridine with a cytosine at position -5 increases the affinity of the RNA to the dimer significantly. The complex with RNA stem-loop having cytosine at this position differs from that of the wild-type complex mainly by having one extra intramolecular RNA interaction and one extra water-mediated hydrogen bond. (C) 1997 Academic Press Limited.