Abstract
The DEAD-box protein DDX6 is a central component of translational repression mechanisms in maternal mRNA storage in oocytes and microRNA-mediated silencing in somatic cells. DDX6 interacts with the CCR4-NOT complex and functions in concert with several post-transcriptional regulators, including Edc3, Pat1, and 4E-T. We show that the conserved CUP-homology domain (CHD) of human 4E-T interacts directly with DDX6 in both the presence and absence of the central MIF4G domain of CNOT1. The 2.1-Å resolution structure of the corresponding ternary complex reveals how 4E-T CHD wraps around the RecA2 domain of DDX6 and contacts CNOT1. Although 4E-T CHD lacks recognizable sequence similarity with Edc3 or Pat1, it shares the same DDX6-binding surface. In contrast to 4E-T, however, the Edc3 and Pat1 FDF motifs dissociate from DDX6 upon CNOT1 MIF4G binding in vitro. The results underscore the presence of a complex network of simultaneous and/or mutually exclusive interactions in DDX6-mediated repression.
Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Binding Sites / genetics
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Binding Sites / physiology
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Carrier Proteins / chemistry*
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Carrier Proteins / genetics
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Carrier Proteins / metabolism*
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DEAD-box RNA Helicases / chemistry
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DEAD-box RNA Helicases / genetics
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DEAD-box RNA Helicases / metabolism*
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Humans
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Models, Biological
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Nuclear Receptor Subfamily 4, Group A, Member 2 / chemistry*
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Nuclear Receptor Subfamily 4, Group A, Member 2 / genetics
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Nuclear Receptor Subfamily 4, Group A, Member 2 / metabolism*
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Nucleocytoplasmic Transport Proteins / chemistry
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Nucleocytoplasmic Transport Proteins / genetics
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Nucleocytoplasmic Transport Proteins / metabolism*
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Protein Binding / genetics
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Protein Binding / physiology
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Protein Structure, Secondary
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Proto-Oncogene Proteins / chemistry
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Proto-Oncogene Proteins / genetics
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Proto-Oncogene Proteins / metabolism*
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Receptors, CCR4 / chemistry
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Receptors, CCR4 / genetics
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Receptors, CCR4 / metabolism*
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Transcription Factors / chemistry
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Transcription Factors / genetics
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Transcription Factors / metabolism*
Substances
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CNOT1 protein, human
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Carrier Proteins
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EIF4ENIF1 protein, human
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NR4A2 protein, human
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Nuclear Receptor Subfamily 4, Group A, Member 2
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Nucleocytoplasmic Transport Proteins
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Proto-Oncogene Proteins
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Receptors, CCR4
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Transcription Factors
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DDX6 protein, human
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DEAD-box RNA Helicases