Smu1 and RED are required for activation of spliceosomal B complexes assembled on short introns
Smu1 and RED are required for activation of spliceosomal B complexes assembled on short introns
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DOI：
10.1038/s41467-019-11293-8
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发表时间：
2019-08-13
影响因子：
16.6
通讯作者：
Luehrmann, Reinhard
中科院分区：
文献类型：
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作者：
Keiper, Sandra;Papasaikas, Panagiotis;Luehrmann, Reinhard
人类预催化剪接体含有几种蛋白质，这些蛋白质在剪接体激活之前短暂结合，并且在酵母中不存在，这表明这一关键步骤在高等真核生物中更为复杂。我们通过RNAi结合RNA-Seq证明了其中两种人类特异性蛋白Smu1和RED既可以作为备选剪接调节因子，也可以作为一般剪接因子，主要用于短内含子的有效剪接。体外剪接实验表明Smu1和RED促进剪接体的激活，并且当pre-mRNA的5'剪接位点（SS）和分支位点（BS）之间的距离足够短时，Smu1和RED对于这一步骤至关重要。当短内含子的5‘和3’区域物理分离时，可以绕过Smu1-RED要求。我们的观察结果表明Smu1和RED减轻了由于短5ss - bs距离引起的物理限制，从而使剪接体能够克服与短内含子剪接相关的结构挑战。
Human pre-catalytic spliceosomes contain several proteins that associate transiently just prior to spliceosome activation and are absent in yeast, suggesting that this critical step is more complex in higher eukaryotes. We demonstrate via RNAi coupled with RNA-Seq that two of these human-specific proteins, Smu1 and RED, function both as alternative splicing regulators and as general splicing factors and are required predominantly for efficient splicing of short introns. In vitro splicing assays reveal that Smu1 and RED promote spliceosome activation, and are essential for this step when the distance between the pre-mRNA's 5' splice site (SS) and branch site (BS) is sufficiently short. This Smu1-RED requirement can be bypassed when the 5' and 3' regions of short introns are physically separated. Our observations suggest that Smu1 and RED relieve physical constraints arising from a short 5'SS-BS distance, thereby enabling spliceosomes to overcome structural challenges associated with the splicing of short introns.