Structure of the phylogenetically most conserved domain of SRP RNA.
Structure of the phylogenetically most conserved domain of SRP RNA.
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SRP RNA 系统发育上最保守的结构域的结构。
DOI：
10.1017/s1355838299991458
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
James,TL
中科院分区：
文献类型：
--
作者：
Schmitz,U;Behrens,S;Freymann,DM;Keenan,RJ;Lukavsky,P;Walter,P;James,TL
信号识别颗粒(SRP)是一种系统发育保守的核糖核蛋白，需要将蛋白质共翻译靶向细菌质膜的内质网膜。SRP RNA的IV结构域由一个短茎环结构组成，其中有两个内部环，其中包含分子中最保守的核苷酸。所有已知的SRP的基本相互作用都发生在含有结构域IV的部分。通过多维核磁共振和约束分子动力学精化确定了包含完整的大肠杆菌结构域IV的43个核苷酸的RNA的溶液结构。我们的数据证实了先前确定的包含最保守、对称内环A的较小亚片段的刚性结构(Schmitz等人，NAT Struct Biol，1999，6：634-638)，其中所有保守的核苷酸都参与核苷酸特异性的结构相互作用。不对称的内环B在RNA分子中提供了一个铰链；它部分是灵活的，但也是独特的结构。较长的内环B链通过创建窗台状排列来延伸主槽；然而，对于环B，保守的核苷酸没有明显的结构作用。结构域IV的结构表明，环A是RNA/蛋白质相互作用的初始部位，产生特异性，而环B提供第二个相互作用部位。
The signal recognition particle (SRP) is a phylogenetically conserved ribonucleoprotein required for cotranslational targeting of proteins to the membrane of the endoplasmic reticulum of the bacterial plasma membrane. Domain IV of SRP RNA consists of a short stem-loop structure with two internal loops that contain the most conserved nucleotides of the molecule. All known essential interactions of SRP occur in that moiety containing domain IV. The solution structure of a 43-nt RNA comprising the complete Escherichia coli domain IV was determined by multidimensional NMR and restrained molecular dynamics refinement. Our data confirm the previously determined rigid structure of a smaller subfragment containing the most conserved, symmetric internal loop A (Schmitz et al., Nat Struct Biol, 1999, 6:634–638), where all conserved nucleotides are involved in nucleotide-specific structural interactions. Asymmetric internal loop B provides a hinge in the RNA molecule; it is partially flexible, yet also uniquely structured. The longer strand of internal loop B extends the major groove by creating a ledge-like arrangement; for loop B however, there is no obvious structural role for the conserved nucleotides. The structure of domain IV suggests that loop A is the initial site for the RNA/protein interaction creating specificity, whereas loop B provides a secondary interaction site.