Regulation of Prp43-mediated disassembly of spliceosomes by its cofactors Ntr1 and Ntr2.
Regulation of Prp43-mediated disassembly of spliceosomes by its cofactors Ntr1 and Ntr2.
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DOI：
10.1093/nar/gkw1225
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发表时间：
2017-04-20
影响因子：
14.9
通讯作者：
Lührmann R
中科院分区：
文献类型：
--
作者：
Fourmann JB;Tauchert MJ;Ficner R;Fabrizio P;Lührmann R
Deah-box NTPase Prp43与辅因子Ntr1/Spp382和Ntr2协同分解剪接体，形成NTR复合体。Prp43如何受其辅因子的调节，选择性地只丢弃内质剪接体(ILs)和有缺陷的剪接体，并防止早期正确组装/野生型剪接体的拆解，目前尚不清楚。首先，我们证明了Ntr1΄S G-Patch基序可以被Prp43΄S核糖体生物发生中的辅因子Pfa1/Sqs1的GP基序所取代，证明了Ntr1GP的特定功能是激活Prp43进行剪接体分解，而不是引导Prp43到其在剪接体中的结合位置。此外，我们还发现，Ntr1΄S的C-末端结构域通过阻止Prp43破坏ILS以外的野生型剪接体而发挥保护作用。Ntr1和Ntr2也可以区分野生型和缺陷型剪接体。在这两种剪接体中，Ntr1-CTD阻碍Prp43介导的拆解，而Ntr1GP促进拆卸。有趣的是，Ntr2在有缺陷的剪接体中扮演着特殊的角色，可能是通过稳定Ntr1并允许Prp43与Ntr1的GP基序进行有效的相互作用来实现的。我们的数据表明，Ntr1和Ntr2起到了‘守门人’的作用，并表明这两个辅助因子都可以检查剪接体复合体的RNP结构，从而针对次优的剪接体进行Prp43介导的分解。
The DEAH-box NTPase Prp43 disassembles spliceosomes in co-operation with the cofactors Ntr1/Spp382 and Ntr2, forming the NTR complex. How Prp43 is regulated by its cofactors to discard selectively only intron-lariat spliceosomes (ILS) and defective spliceosomes and to prevent disassembly of earlier and properly assembled/wild-type spliceosomes remains unclear. First, we show that Ntr1΄s G-patch motif (Ntr1GP) can be replaced by the GP motif of Pfa1/Sqs1, a Prp43΄s cofactor in ribosome biogenesis, demonstrating that the specific function of Ntr1GP is to activate Prp43 for spliceosome disassembly and not to guide Prp43 to its binding site in the spliceosome. Furthermore, we show that Ntr1΄s C-terminal domain (CTD) plays a safeguarding role by preventing Prp43 from disrupting wild-type spliceosomes other than the ILS. Ntr1 and Ntr2 can also discriminate between wild-type and defective spliceosomes. In both type of spliceosomes, Ntr1-CTD impedes Prp43-mediated disassembly while the Ntr1GP promotes disassembly. Intriguingly, Ntr2 plays a specific role in defective spliceosomes, likely by stabilizing Ntr1 and allowing Prp43 to enter a productive interaction with the GP motif of Ntr1. Our data indicate that Ntr1 and Ntr2 act as ‘doorkeepers’ and suggest that both cofactors inspect the RNP structure of spliceosomal complexes thereby targeting suboptimal spliceosomes for Prp43-mediated disassembly.