A DDX6-CNOT1 Complex and W-Binding Pockets in CNOT9 Reveal Direct Links between miRNA Target Recognition and Silencing
A DDX6-CNOT1 Complex and W-Binding Pockets in CNOT9 Reveal Direct Links between miRNA Target Recognition and Silencing
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DOI：
10.1016/j.molcel.2014.03.034
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发表时间：
2014-06-05
期刊：
影响因子：
16
通讯作者：
Izaurralde, Elisa
中科院分区：
文献类型：
--
作者：
Chen, Ying;Boland, Andreas;Izaurralde, Elisa
CCR 4-NOT是miRNA介导的基因沉默中的主要效应复合物。它通过与TNRC 6/GW 182蛋白中含有色氨酸（W）的基序相互作用被募集到miRNA靶标，并且是miRNA靶标的翻译抑制和降解所需的。在这里，我们阐明了CCR 4-NOT的抑制活性及其与TNRC 6/GW 182的相互作用的结构基础。我们发现保守的hocT 9亚基连接到hocT 1支架中的未知功能域（DUF 3819）。所得复合物提供了TNRC 6/GW 182的结合位点，其晶体结构揭示了位于hocT 9中的串联W结合口袋。我们进一步表明，hocT 1 MIF 4G结构域与DDX 6的C-末端RecA结构域相互作用，DDX 6是一种翻译阻遏物和去帽激活剂。该复合物的晶体结构与eIF 4G-eIF 4A复合物具有惊人的相似性。总之，我们的数据提供了一个分子途径中缺失的物理链接，该分子途径将miRNA靶点识别与翻译抑制、去腺苷化和去帽连接起来。
CCR4-NOT is a major effector complex in miRNA-mediated gene silencing. It is recruited to miRNA targets through interactions with tryptophan (W)containing motifs in TNRC6/GW182 proteins and is required for both translational repression and degradation of miRNA targets. Here, we elucidate the structural basis for the repressive activity of CCR4-NOT and its interaction with TNRC6/GW182s. We show that the conserved CNOT9 subunit attaches to a domain of unknown function (DUF3819) in the CNOT1 scaffold. The resulting complex provides binding sites for TNRC6/GW182, and its crystal structure reveals tandem W-binding pockets located in CNOT9. We further show that the CNOT1 MIF4G domain interacts with the C-terminal RecA domain of DDX6, a translational repressor and decapping activator. The crystal structure of this complex demonstrates striking similarity to the eIF4G-eIF4A complex. Together, our data provide the missing physical links in a molecular pathway that connects miRNA target recognition with translational repression, deadenylation, and decapping.