Mutational analysis of the RNA pseudoknot component of a coronavirus ribosomal frameshifting signal.
Mutational analysis of the RNA pseudoknot component of a coronavirus ribosomal frameshifting signal.
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DOI：
10.1016/0022-2836(91)90361-9
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发表时间：
1991-08-20
影响因子：
5.6
通讯作者：
Inglis SC
中科院分区：
文献类型：
--
作者：
Brierley I;Rolley NJ;Jenner AJ;Inglis SC
冠状病毒IBV的基因组RNA在重叠的1a和1b开放阅读框的交界处含有一个有效的核糖体移码信号。该信号由两个元素组成，一个七核苷酸“滑移位点”和一个以RNA假结形式存在的下游三级RNA结构。我们通过分析一系列伪结突变体的移帧特性，研究了伪结的结构及其对移帧过程的贡献。我们的研究结果表明，伪结结构与当前构建规则预测的结构非常相似，尽管在两个伪结茎被认为同轴堆叠的区域形成碱基对并不是有效帧移的先决条件。然而，这些茎必须靠得很近才能产生功能性结构。一般来说，在任何一个干中去掉一个碱基对接触就足以减少或消除帧移。茎或环中的主要序列决定因素似乎与移码过程无关；只要保持整体结构，换帧是高效的。因此，假结环中的小插入和环2中的删除将其长度减少到预测的功能最小值，不会影响帧移。然而，在环路2中大量插入（467个核苷酸）消除了帧移。一个简单的茎环结构，具有与假结的堆叠茎相同长度和核苷酸组成的碱基配对茎，不能在功能上取代假结，这表明假结的某些特殊构象特征决定了其促进帧移位的能力。
The genomic RNA of the coronavirus IBV contains an efficient ribosomal frameshift signal at the junction of the overlapping 1a and 1b open reading frames. The signal is comprised of two elements, a heptanucleotide “slip-site” and a downstream tertiary RNA structure in the form of an RNA pseudoknot. We have investigated the structure of the pseudoknot and its contribution to the frameshift process by analysing the frameshifting properties of a series of pseudoknot mutants. Our results show that the pseudoknot structure closely resembles that which can be predicted from current building rules, although base-pair formation at the region where the two pseudoknot stems are thought to stack co-axially is not a pre-requisite for efficient frameshifting. The stems, however, must be in close proximity to generate a functional structure. In general, the removal of a single base-pair contact in either stem is sufficient to reduce or abolish frameshifting. No primary sequence determinants in the stems or loops appear to be involved in the frameshift process; as long as the overall structure is maintained, frameshifting is highly efficient. Thus, small insertions into the pseudoknot loops and a deletion in loop 2 that reduced its length to the predicted functional minimum did not influence frameshifting. However, a large insertion (467 nucleotides) into loop 2 abolished frameshifting. A simple stem-loop structure with a base-paired stem of the same length and nucleotide composition as the stacked stems of the pseudoknot could not functionally replace the pseudoknot, suggesting that some particular conformational feature of the pseudoknot determines its ability to promote frameshifting.
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影响因子：
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