SF3b1 mutations associated with myelodysplastic syndromes alter the fidelity of branchsite selection in yeast.
SF3b1 mutations associated with myelodysplastic syndromes alter the fidelity of branchsite selection in yeast.
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DOI：
10.1093/nar/gkw1349
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发表时间：
2017-05-05
影响因子：
14.9
通讯作者：
Hoskins AA
中科院分区：
文献类型：
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作者：
Carrocci TJ;Zoerner DM;Paulson JC;Hoskins AA
剪接体的RNA和蛋白质组分共同作用以识别新生前体mRNA的5′剪接位点、3′剪接位点和分支位点（BS）。SF3b1在招募U2小核核糖核蛋白（snRNP）到分支位点方面起关键作用。人类SF3b1的突变与许多疾病相关，如骨髓增生异常综合征（MDS）和癌症。我们利用与MDS相关的SF3b1突变来探究酵母直系同源物Hsh155在分支位点选择和剪接中的作用。这些等位基因改变了剪接体识别分支位点的方式，并且当相对于分支点腺苷在-2、-1和+1位置存在非共有核苷酸时改变剪接。这表明在具有SF3b1突变的人类中观察到的分支位点使用变化可能是由于分支位点识别的保守机制受到干扰。值得注意的是，不同的HSH155等位基因对剪接产生不同的影响：一些提高分支位点选择的准确性，而另一些则降低准确性。我们的数据支持一种模型，即SF3b1的构象变化促进U2与分支位点的结合，而不依赖于DEAD - box ATP酶Prp5的作用。我们提出SF3b1的功能是稳定弱的U2/分支位点双链体以驱动剪接体组装和剪接。
RNA and protein components of the spliceosome work together to identify the 5΄ splice site, the 3΄ splice site, and the branchsite (BS) of nascent pre-mRNA. SF3b1 plays a key role in recruiting the U2 snRNP to the BS. Mutations in human SF3b1 have been linked to many diseases such as myelodysplasia (MDS) and cancer. We have used SF3b1 mutations associated with MDS to interrogate the role of the yeast ortholog, Hsh155, in BS selection and splicing. These alleles change how the spliceosome recognizes the BS and alter splicing when nonconsensus nucleotides are present at the −2, −1 and +1 positions relative to the branchpoint adenosine. This indicates that changes in BS usage observed in humans with SF3b1 mutations may result from perturbation of a conserved mechanism of BS recognition. Notably, different HSH155 alleles elicit disparate effects on splicing: some increase the fidelity of BS selection while others decrease fidelity. Our data support a model wherein conformational changes in SF3b1 promote U2 association with the BS independently of the action of the DEAD-box ATPase Prp5. We propose that SF3b1 functions to stabilize weak U2/BS duplexes to drive spliceosome assembly and splicing.