Macías Sara, Bragulat Mireia, Tardiff Daniel F, Vilardell Josep
Centre de Regulació Genòmica, Doctor Aiguader 88, 08003 Barcelona, Spain.
Mol Cell. 2008 Jun 20;30(6):732-42. doi: 10.1016/j.molcel.2008.05.002.
The mechanisms of pre-mRNA splicing regulation are poorly understood. Here we dissect how the Saccharomyces cerevisiae ribosomal L30 protein blocks splicing of its pre-mRNA upon binding a kink-turn structure including the 5' splice site. We show that L30 binds the nascent RPL30 transcript without preventing recognition of the 5' splice site by U1 snRNP but blocking U2 snRNP association with the branch site. Interaction of the factors BBP and Mud2 with the intron, relevant for U2 snRNP recruitment, is not affected by L30. Furthermore, the functions of neither the DEAD-box protein Sub2 in the incipient spliceosome nor the U2 snRNP factor Cus2 on branch site recognition are required for L30 inhibition. These findings contrast with the effects caused by binding a heterologous protein to the same region, completely blocking intron recognition. Collectively, our data suggest that L30 represses a spliceosomal rearrangement required for U2 snRNP association with the transcript.
前体mRNA剪接调控的机制目前仍知之甚少。在此，我们剖析了酿酒酵母核糖体L30蛋白在结合包括5'剪接位点在内的一个扭结结构时，是如何阻断其前体mRNA剪接的。我们发现，L30结合新生的RPL30转录本，并不阻止U1 snRNP对5'剪接位点的识别，但会阻断U2 snRNP与分支位点的结合。与U2 snRNP招募相关的BBP和Mud2因子与内含子的相互作用不受L30影响。此外，L30抑制作用既不需要起始剪接体中的DEAD-box蛋白Sub2的功能，也不需要U2 snRNP因子Cus2对分支位点的识别功能。这些发现与将一种异源蛋白结合到同一区域所产生的效应形成对比，后者会完全阻断内含子识别。总体而言，我们的数据表明，L30抑制了U2 snRNP与转录本结合所需的剪接体重排。
