The Leishmania PABP1-eIF4E4 interface: a novel 5'-3' interaction architecture for trans-spliced mRNAs
The Leishmania PABP1-eIF4E4 interface: a novel 5'-3' interaction architecture for trans-spliced mRNAs
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利什曼原虫 PABP1-eIF4E4 界面：反式剪接 mRNA 的新型 5-3 相互作用架构
DOI：
10.1093/nar/gky1187
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发表时间：
2019
影响因子：
14.9
通讯作者：
Dos Santos Rodrigues F
中科院分区：
文献类型：
--
作者：
Dos Santos Rodrigues F
锥虫多顺反子转录物的反式剪接产生多聚腺苷酸化单顺反子mRNA，经修饰形成5′ cap 4结构（m7 Gpppm 36，6，2′ Apm 2 ′ Apm 2 ′ Cpm 23，2′U）。核磁共振和X射线晶体学研究表明利什曼原虫具有一种独特的N-末端延伸的帽结合蛋白（eIF 4 E4），它通过PAM 2基序与PABP 1结合。这依赖于极性和带电荷的氨基酸侧链与多种疏水相互作用的组合的相互作用，并支持了利什曼原虫4结合翻译因子复合物中的新结构。使用微尺度热泳，荧光各向异性和表面等离子体共振测量表征的关键相互作用驱动theLeishmaniatranslation起始复合物的组装。我们证明，这种复合物可以deliverateLeishmaniaeIF 4G 3，不像标准的真核起始复合物的范例，紧密结合eIF 4 E4，但不PABP 1。因此，在利什曼原虫中，相互作用链5′ cap 4-eIF 4 E4-PABP 1-poly（A）桥接mRNA 5′和3′末端。因此，通过与两个蛋白质配体和mRNA 5′帽4结构紧密结合，锥虫N末端延伸形式的eIF 4 E作为mRNA帽结合复合物的核心分子支架。最后，eIF 4 E4 N-末端延伸是一个内在无序的区域，在与PABP 1结合时转变为部分折叠的形式，由此这种相互作用不受与PABP 1结合的poly（A）的调节。
Trans-splicing of trypanosomatid polycistronic transcripts produces polyadenylated monocistronic mRNAs modified to form the 5′ cap4 structure (m7Gpppm36,6,2′Apm2′Apm2′Cpm23,2′U). NMR and X-ray crystallography reveal thatLeishmaniahas a unique type of N-terminally-extended cap-binding protein (eIF4E4) that binds via a PAM2 motif to PABP1. This relies on the interactions of a combination of polar and charged amino acid side-chains together with multiple hydrophobic interactions, and underpins a novel architecture in theLeishmaniacap4-binding translation factor complex. Measurements using microscale thermophoresis, fluorescence anisotropy and surface plasmon resonance characterize the key interactions driving assembly of theLeishmaniatranslation initiation complex. We demonstrate that this complex can accommodateLeishmaniaeIF4G3 which, unlike the standard eukaryotic initiation complex paradigm, binds tightly to eIF4E4, but not to PABP1. Thus, inLeishmania, the chain of interactions 5′cap4-eIF4E4–PABP1-poly(A) bridges the mRNA 5′ and 3′ ends. Exceptionally, therefore, by binding tightly to two protein ligands and to the mRNA 5′ cap4 structure, the trypanosomatid N-terminally extended form of eIF4E acts as the core molecular scaffold for the mRNA-cap-binding complex. Finally, the eIF4E4 N-terminal extension is an intrinsically disordered region that transitions to a partly folded form upon binding to PABP1, whereby this interaction is not modulated by poly(A) binding to PABP1.