A novel 3' splice site recognition by the two zinc fingers in the U2AF small subunit.
A novel 3' splice site recognition by the two zinc fingers in the U2AF small subunit.
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DOI：
10.1101/gad.267104.115
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发表时间：
2015-08-01
影响因子：
10.5
通讯作者：
Obayashi E
中科院分区：
文献类型：
--
作者：
Yoshida H;Park SY;Oda T;Akiyoshi T;Sato M;Shirouzu M;Tsuda K;Kuwasako K;Unzai S;Muto Y;Urano T;Obayashi E
真核细胞的前体mRNA剪接反应必须非常精确地进行，因为不能正确识别剪接位点会导致严重的疾病。U2AF异源二聚体的小亚基对于前体mRNA剪接中3′剪接位点的确定至关重要，并且U2AF小亚基的几个单残基突变导致严重的疾病，如骨髓增生异常综合征。然而，RNA识别的机制知之甚少。在这里，我们解决了晶体结构的U2AF小亚基（U2AF23）从裂殖酵母，由一个RNA识别基序（RRM）域两侧的两个保守的CCCH型锌指（ZF）。两个ZF并排位于RRM结构域的β折叠上。进一步的突变分析显示，ZF与靶RNA序列协同结合，但RRM结构域仅作为组织ZF的支架，本身并不直接接触RNA。U2AF小亚基的这种完全新颖和意想不到的RNA结合机制模式揭示了这种高度保守蛋白质突变引起的剪接错误。
The pre-mRNA splicing reaction of eukaryotic cells has to be carried out extremely accurately, as failure to recognize the splice sites correctly causes serious disease. The small subunit of the U2AF heterodimer is essential for the determination of 3′ splice sites in pre-mRNA splicing, and several single-residue mutations of the U2AF small subunit cause severe disorders such as myelodysplastic syndromes. However, the mechanism of RNA recognition is poorly understood. Here we solved the crystal structure of the U2AF small subunit (U2AF23) from fission yeast, consisting of an RNA recognition motif (RRM) domain flanked by two conserved CCCH-type zinc fingers (ZFs). The two ZFs are positioned side by side on the β sheet of the RRM domain. Further mutational analysis revealed that the ZFs bind cooperatively to the target RNA sequence, but the RRM domain acts simply as a scaffold to organize the ZFs and does not itself contact the RNA directly. This completely novel and unexpected mode of RNA-binding mechanism by the U2AF small subunit sheds light on splicing errors caused by mutations of this highly conserved protein.