A potential role for U2AF-SAP 155 interactions in recruiting U2 snRNP to the branch site
A potential role for U2AF-SAP 155 interactions in recruiting U2 snRNP to the branch site
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DOI：
10.1128/mcb.18.8.4752
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发表时间：
1998-08-01
影响因子：
5.3
通讯作者：
Reed, R
中科院分区：
文献类型：
--
作者：
Gozani, O;Potashkin, J;Reed, R
U2 snRNA和分支点序列（BPS）之间的碱基配对对于前体mRNA剪接是必不可少的。由于后生动物BPS是短的和高度简并的，这种相互作用本身是不足以特异性结合的U2 snRNP。剪接因子U2 AF在最早的剪接体复合物E的3'剪接位点与嘧啶段结合，并且对于剪接体复合物A中的U2 snRNP结合至关重要。我们表明，U2 snRNP蛋白SAP 155 UV交联前mRNA的两侧的BPS在A复合物。SAP 155的下游交联位点紧邻U2 AF结合位点，并且这两种蛋白质在蛋白质-蛋白质相互作用测定中直接相互作用。使用UV交联，连同含有重复BPS的前mRNA的功能分析，我们显示BPS选择和SAP 155在BPS两侧的UV交联之间的直接相关性。总之，我们的数据与U2 AF结合E复合物中的嘧啶段，然后与SAP 155相互作用以将U2 snRNP募集到BPS的模型一致。
Base pairing between U2 snRNA and the branchpoint sequence (BPS) is essential for pre mRNA splicing. Because the metazoan BPS is short and highly degenerate, this interaction alone is insufficient for specific binding of U2 snRNP. The splicing factor U2AF binds to the pyrimidine tract at the 3' splice site in the earliest spliceosomal complex, E, and is essential for U2 snRNP binding in the spliceosomal complex A. We show that the U2 snRNP protein SAP 155 UV cross-links to pre-mRNA on both sides of the BPS in the A complex. SAP 155's downstream cross-linking site is immediately adjacent to the U2AF binding site, and the two proteins interact directly in protein-protein interaction assays. Using UV cross-linking, together with functional analyses of pre-mRNAs containing duplicated BPSs, we show a direct correlation between BPS selection and UV cross-linking of SAP 155 on both sides of the BPS. Together, our data are consistent with a model in which U2AF binds to the pyrimidine tract in the E complex and then interacts with SAP 155 to recruit U2 snRNP to the BPS.