Bag-1 internal ribosome entry segment activity is promoted by structural changes mediated by Poly(rC) binding protein 1 and recruitment of polypyrimidine tract binding protein 1
Bag-1 internal ribosome entry segment activity is promoted by structural changes mediated by Poly(rC) binding protein 1 and recruitment of polypyrimidine tract binding protein 1
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DOI：
10.1128/mcb.24.12.5595-5605.2004
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发表时间：
2004-06-01
影响因子：
5.3
通讯作者：
Willis, AE
中科院分区：
文献类型：
--
作者：
Pickering, BM;Mitchell, SA;Willis, AE
我们之前已经证明，内部核糖体进入片段 (IRES) 指导 Bag-1 p36 同种型的合成，并且聚嘧啶束结合蛋白 1 (PTB-1) 和聚 (rC) 结合蛋白 1 (PCBP1) 在体外和体内刺激 IRES 介导的翻译起始。在这里，通过使用化学和酶探测数据作为 RNA 折叠算法 Mfold 的约束，导出了 Bag-1 IRES 的二级结构模型。核糖体进入窗口已在该结构模型中被识别，并且位于许多残基参与碱基配对相互作用的区域。 PTB-1 和 PCBP1 与其 IRES 上的同源结合位点的相互作用破坏了许多 RNA-RNA 相互作用，这产生了一个大约 40 个核苷酸的非结构化区域，可以允许核糖体结合。 PTB-1 和 PCBP1 结合位点的突变分析表明，PCBP1 作为 RNA 伴侣在核糖体进入窗口附近打开 RNA，而 PTB-1 可能是预起始复合物的重要组成部分。
We have shown previously that an internal ribosome entry segment (IRES) directs the synthesis of the p36 isoform of Bag-1 and that polypyrimidine tract binding protein 1 (PTB-1) and poly(rC) binding protein 1 (PCBP1) stimulate IRES-mediated translation initiation in vitro and in vivo. Here, a secondary structural model of the Bag-1 IRES has been derived by using chemical and enzymatic probing data as constraints on the RNA folding algorithm Mfold. The ribosome entry window has been identified within this structural model and is located in a region in which many residues are involved in base-pairing interactions. The interactions of PTB-1 and PCBP1 with their cognate binding sites on the IRES disrupt many of the RNA-RNA interactions, and this creates a largely unstructured region of approximately 40 nucleotides that could permit ribosome binding. Mutational analysis of the PTB-1 and PCBP1 binding sites suggests that PCBP1 acts as an RNA chaperone to open the RNA in the vicinity of the ribosome entry window while PTB-1 is probably an essential part of the preinitiation complex.