The DEAD-box protein Ded1 modulates translation by the formation and resolution of an eIF4F-mRNA complex.
The translation, localization, and degradation of cytoplasmic mRNAs are controlled by the formation and rearrangement of their mRNPs. The conserved Ded1/DDX3 DEAD-box protein functions in an unknown manner to affect both translation initiation and repression. We demonstrate that Ded1 first functions by directly interacting with eIF4G to assemble a Ded1-mRNA-eIF4F ... complex, which accumulates in stress granules. After ATP hydrolysis by Ded1, the mRNP exits stress granules and completes translation initiation. Thus, Ded1 functions both as a repressor of translation, by assembling an mRNP stalled in translation initiation, and as an ATP-dependent activator of translation, by resolving the stalled mRNP. These results identify Ded1 as a translation initiation factor that assembles and remodels an intermediate complex in translation initiation.
Mesh Terms:
Adenosine Triphosphate, Amino Acid Sequence, Cytoplasmic Granules, DEAD-box RNA Helicases, Eukaryotic Initiation Factor-4F, Eukaryotic Initiation Factor-4G, Gene Expression Regulation, Models, Genetic, Molecular Sequence Data, Protein Biosynthesis, RNA, Messenger, Ribonucleoproteins, Saccharomyces cerevisiae Proteins, Sequence Alignment
Adenosine Triphosphate, Amino Acid Sequence, Cytoplasmic Granules, DEAD-box RNA Helicases, Eukaryotic Initiation Factor-4F, Eukaryotic Initiation Factor-4G, Gene Expression Regulation, Models, Genetic, Molecular Sequence Data, Protein Biosynthesis, RNA, Messenger, Ribonucleoproteins, Saccharomyces cerevisiae Proteins, Sequence Alignment
Mol. Cell
Date: Sep. 16, 2011
PubMed ID: 21925384
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