The invariant U5 snRNA loop 1 sequence is dispensable for the first catalytic step of pre-mRNA splicing in yeast
The invariant U5 snRNA loop 1 sequence is dispensable for the first catalytic step of pre-mRNA splicing in yeast
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DOI：
10.1016/s0092-8674(00)80140-3
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发表时间：
1996-08-23
期刊：
影响因子：
64.5
通讯作者：
Newman, AJ
中科院分区：
文献类型：
--
作者：
OKeefe, RT;Norman, C;Newman, AJ
我们建立了一个体外重组系统来研究U5SnRNA在前mRNA剪接的两个催化步骤中的作用。已知不变的U5环1在第一催化步骤之前与5‘剪接点的外显子序列相互作用。值得注意的是，对U5突变的体外分析表明，第一次酯交换是在没有U5环的情况下准确发生的。因此，该序列不是第一个催化步骤的剪接体活性部位的重要组成部分。第二个催化步骤，尽管强烈依赖于U5环的存在来连接外显子1剪接中间产物，但令人惊讶的是对不变序列中的突变具有耐受性。
We have developed an in vitro reconstitution system to investigate the role of U5 snRNA in the two catalytic steps of pre-mRNA splicing. The invariant U5 loop 1 is known to interact with exon sequences at the 5' splice site before the first catalytic step. Remarkably, analysis of U5 mutations in vitro reveals that the first transesterification occurs accurately in the absence of the U5 loop. Therefore this sequence is not an essential component of the spliceosomal active site for the first catalytic step. The second catalytic step, although strongly dependent on the presence of a U5 loop to tether the exon 1 splicing intermediate, is surprisingly tolerant of mutations in the invariant sequence.