A potential RNA drug target in the hepatitis C virus internal ribosomal entry site
A potential RNA drug target in the hepatitis C virus internal ribosomal entry site
复制标题
DOI：
10.1017/s1355838200000935
复制
发表时间：
2000-10-01
期刊：
影响因子：
4.5
通讯作者：
Aboul-Ela, F
中科院分区：
文献类型：
--
作者：
Klinck, R;Westhof, E;Aboul-Ela, F
来自丙型肝炎病毒（HCV）内部核糖体进入位点（IRES）的亚结构域IIId已被证明对帽无关翻译至关重要。我们对与IIId序列相同的27-nt片段进行了结构研究，以探索该子结构域的结构特征。提出的IIId二级结构由两个3bp螺旋区域组成，由一个内部环分隔，一端由一个6-nt末端环闭合。核磁共振和分子模型相互作用，建立了一个验证模型的三维结构的IIId。我们发现该片段包含几个非规范结构基序和非沃森-克里克碱基对，其中一些是其他rna所共有的，特别是rRNA α -sarcin/ricin环的一个特征基序位于内部环中。末端环，5'- uguggu，被发现折叠形成一个由跨摆动U（）关闭的三核苷酸环。G碱基对。第六个核苷酸被凸出，以允许这个U（）堆叠。相邻螺旋区域上的G对。在完整IRES背景下的体内突变分析证实了iid中每个结构基序对IRES功能的重要性。这些发现可能为宿主细胞蛋白在ires定向翻译中发挥作用，特别是宿主核糖体为病毒功能而隔离的机制提供线索。
Subdomain IIId from the hepatitis C virus (HCV) internal ribosome entry site (IRES) has been shown to be essential for cap-independent translation. We have conducted a structural study of a 27-nt fragment, identical in sequence to IIId, to explore the structural features of this subdomain, The proposed secondary structure of IIId is comprised of two 3 bp helical regions separated by an internal loop and closed at one end by a 6-nt terminal loop. NMR and molecular modeling were used interactively to formulate a validated model of the three-dimensional structure of IIId. We found that this fragment contains several noncanonical structural motifs and non-Watson-Crick base pairs, some of which are common to other RNAs, In particular, a motif characteristic of the rRNA alpha -sarcin/ricin loop was located in the internal loop. The terminal loop, 5'-UUGGGU, was found to fold to form a trinucleotide loop closed by a trans-wobble U(.)G base pair. The sixth nucleotide was bulged out to allow stacking of this U(.)G pair on the adjacent helical region. In vivo mutational analysis in the context of the full IRES confirmed the importance of each structural motif within IIId for IRES function. These findings may provide clues as to host cellular proteins that play a role in IRES-directed translation and, in particular, the mechanism through which host ribosomes are sequestered for viral function.