A role for ubiquitin in the spliceosome assembly pathway
A role for ubiquitin in the spliceosome assembly pathway
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DOI：
10.1038/nsmb.1401
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发表时间：
2008-05-01
影响因子：
16.8
通讯作者：
Sontheimer, Erik J.
中科院分区：
文献类型：
--
作者：
Bellare, Priya;Small, Eliza C.;Sontheimer, Erik J.
剪接体使用多种策略来调节其在mRNA成熟中的功能。泛素调节许多细胞过程，但其在剪接过程中的潜在作用是未知的。我们已经开发了一种新的策略，揭示了泛素在剪接复合物的动力学中的直接作用。泛素突变体（I44 A）可以进入缀合途径但在下游功能中受损，其通过降低U4/U6-U 5小核核糖核蛋白（snRNP）的水平来降低剪接活性。类似地，泛素的蛋白质-蛋白质相互作用的抑制剂，泛素A，在体外降低U4/U6-U 5三重snRNP水平。当泛素相互作用被阻断时，纯化的U4/U6-U 5颗粒的ATP依赖性解体被加速，表明泛素在抑制U4/U6解旋中的直接作用。最后，我们表明，保守的剪接因子Prp 8是纯化的三重snRNP内的泛素化。这些结果揭示了一个以前未知的泛素依赖性机制，用于控制前mRNA剪接途径。
The spliceosome uses numerous strategies to regulate its function in mRNA maturation. Ubiquitin regulates many cellular processes, but its potential roles during splicing are unknown. We have developed a new strategy that reveals a direct role for ubiquitin in the dynamics of splicing complexes. A ubiquitin mutant (I44A) that can enter the conjugation pathway but is compromised in downstream functions diminishes splicing activity by reducing the levels of the U4/U6-U5 small nuclear ribonucleoprotein (snRNP). Similarly, an inhibitor of ubiquitin's protein-protein interactions, ubistatin A, reduces U4/U6-U5 triple snRNP levels in vitro. When ubiquitin interactions are blocked, ATP-dependent disassembly of purified U4/U6-U5 particles is accelerated, indicating a direct role for ubiquitin in repressing U4/U6 unwinding. Finally, we show that the conserved splicing factor Prp8 is ubiquitinated within purified triple snRNPs. These results reveal a previously unknown ubiquitin-dependent mechanism for controlling the pre-mRNA splicing pathway.