Cotranscriptional spliceosome assembly occurs in a stepwise fashion and requires the cap binding complex
Cotranscriptional spliceosome assembly occurs in a stepwise fashion and requires the cap binding complex
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DOI：
10.1016/j.molcel.2005.05.007
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发表时间：
2005-07-01
期刊：
影响因子：
16
通讯作者：
Neugebauer, KM
中科院分区：
文献类型：
--
作者：
Görnemann, J;Kotovic, KM;Neugebauer, KM
转录与前体mRNA剪接之间的偶联是基因表达中的一个关键调控机制。在此，我们研究了酵母中的共转录剪接体组装，利用体内交联来确定剪接体组分沿含内含子基因的分布。检测到U1、U2和U5小核核糖核蛋白颗粒（snRNPs）以及3'剪接位点结合因子Mud2p和BBP的积累模式表明了逐步且完整的剪接体组装；十九复合体（NTC）组分Prp19p的募集表明剪接催化也是共转录的。U1、U2和U5 snRNPs各自的动力学与单个snRNPs的逐步募集相一致，而非如最近所提出的预先形成的“五聚体snRNP”。最后，我们表明帽结合复合体（CBC）对于共转录剪接体组装是必要的，但并非充分的。因此，体内CBC与剪接体组装之间关键联系的证明表明5'端加帽将前体mRNA剪接与转录偶联起来。
Coupling between transcription and pre-mRNA splicing is a key regulatory mechanism in gene expression. Here, we investigate cotranscriptional spliceosome assembly in yeast, using in vivo crosslinking to determine the distribution of spliceosome components along intron-containing genes. Accumulation of the U1, U2, and U5 small nuclear ribonucleoprotein particles (snRNPs) and the 3 ' splice site binding factors Mud2p and BBP was detected in patterns indicative of progressive and complete spliceosome assembly; recruitment of the nineteen complex (NTC) component Prp19p suggests that splicing catalysis is also cotranscriptional. The separate dynamics of the U1, U2, and U5 snRNPs are consistent with stepwise recruitment of individual snRNPs rather than a preformed "penta-snRNP," as recently proposed. Finally, we show that the cap binding complex (CBC) is necessary, but not sufficient, for cotranscriptional spliceosome assembly. Thus, the demonstration of an essential link between CBC and spliceosome assembly in vivo indicates that 5 ' end capping couples pre-mRNA splicing to transcription.