The length but not the sequence of the polyoma virus late leader exon is important for both late RNA splicing and stability.
The length but not the sequence of the polyoma virus late leader exon is important for both late RNA splicing and stability.
复制标题
多瘤病毒晚期前导外显子的长度而非序列对于晚期 RNA 剪接和稳定性都很重要。
DOI：
10.1093/nar/15.6.2593
复制
发表时间：
1987
影响因子：
14.9
通讯作者：
Carmichael,GG
中科院分区：
文献类型：
--
作者：
Adami,GR;Carmichael,GG
多瘤病毒晚期RNA加工为研究体内剪接机制提供了一个方便的模型系统。为了进一步了解未翻译的“晚期先导”单元在晚期RNA加工中的作用，我们构建了一组先导外显子缺失和替换的多瘤病毒。这使得我们能够确定在这个系统中，前mRNA剪接和稳定性都需要一个最小的外显子大小。我们在这里表明，具有9个碱基的晚期前导单位的突变体(ALM)的不存活是由于后期RNA剪接中的一般缺陷。此外，ALM感染的细胞在晚期核RNA(剪接或非剪接)的积累方面至少显示出40倍的抑制。然而，ALM晚期启动子的功能几乎正常。具有51-96个碱基的无关联序列长外显子的替代前导变体是可行的(G.Adami和G.Carmichael，J.Virol。58,417-425,1986)。我们在这里表明，来自这些替换的前导突变体之一(包含51个碱基的前导外显子)的晚期RNA在野生型水平上被剪接，几乎没有积累缺陷。因此，在多瘤系统中，仅由9个碱基隔开的剪接位点可以抑制彼此的使用，推测是通过空间位阻干扰。我们认为这种类型的抑制会导致RNA的极端不稳定。
Polyoma virus late RNA processing provides a convenient model system in which to study the mechanics of splicing in vivo. In order to understand further the role of the untranslated “late leader” unit in late RNA processing we have constructed a group of polyoma viruses with deletions and substitutions in the leader exon. This has allowed us to determine that there is a minimum exon size required for both pre-mRNA splicing and stability in this system. We show here that the non-viability of a mutant (ALM) with a 9 base late leader unit is due to a general defect in late RNA splicing. In addition, ALM-infected cells show at least 40-fold depression in the accumulation of late nuclear RNA (spliced or unspliced). The ALM late promoter, however, functions nearly normally. Substituted leader variants with 51- to 96-base long exons of unrelated sequence are viable (G. Adami and G. Carmichael, J. Virol. 58, 417-425, 1986). We show here that late RNA from one of these substituted leader mutants (containing a 51-base leader exon) is spliced at wild type levels, with virtually no defect in accumulation. Thus, in the polyoma system, splice sites separated by only 9 bases can inhibit each others usage, presumably by steric interference. We suggest that this type of inhibition leads to extreme RNA instability.