DEAD-box helicase eIF4A2 inhibits CNOT7 deadenylation activity
DEAD-box helicase eIF4A2 inhibits CNOT7 deadenylation activity
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DOI：
10.1093/nar/gkz509
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发表时间：
2019-09-05
影响因子：
14.9
通讯作者：
Bushell, Martin
中科院分区：
文献类型：
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作者：
Meijer, Hedda A.;Schmidt, Tobias;Bushell, Martin
CCR4-NOT复合物在mrna的翻译抑制和死蛋白化中起重要作用。然而，人们对相互作用因素的具体作用知之甚少。我们证明DEAD-box解旋酶eIF4A2和DDX6直接与CNOT1的MA3和MIF结构域相互作用并竞争结合。此外，我们现在表明，与DDX6相比，将eIF4A2掺入CCR4-NOT复合物抑制CNOT7死基化活性，而DDX6则增强CNOT7活性。内源性mrna的聚腺苷化测试（PAT）确定eIF4A2结合的mrna比DDX6结合的mrna具有更长的聚(A)尾部。免疫沉淀实验表明，eIF4A2不抑制CNOT7与CCR4-NOT复合物的关联，而是抑制CNOT7的活性。我们发现了一个CCR4-NOT相互作用因子TAB182，它调节解旋酶募集到CCR4-NOT复合体中，潜在地影响目标mRNA的结果。综上所述，这些数据表明mRNA的命运取决于eIF4A2或DDX6对CCR4-NOT复合体的特异性募集，从而导致不同的翻译抑制和mRNA死蛋白化途径。
The CCR4-NOT complex plays an important role in the translational repression and deadenylation of mRNAs. However, little is known about the specific roles of interacting factors. We demonstrate that the DEAD-box helicases eIF4A2 and DDX6 interact directly with the MA3 and MIF domains of CNOT1 and compete for binding. Furthermore, we now show that incorporation of eIF4A2 into the CCR4-NOT complex inhibits CNOT7 deadenylation activity in contrast to DDX6 which enhances CNOT7 activity. Polyadenylation tests (PAT) on endogenous mRNAs determined that eIF4A2 bound mRNAs have longer poly(A) tails than DDX6 bound mRNAs. Immunoprecipitation experiments show that eIF4A2 does not inhibit CNOT7 association with the CCR4-NOT complex but instead inhibits CNOT7 activity. We identified a CCR4-NOT interacting factor, TAB182, that modulates helicase recruitment into the CCR4-NOT complex, potentially affecting the outcome for the targeted mRNA. Together, these data show that the fate of an mRNA is dependent on the specific recruitment of either eIF4A2 or DDX6 to the CCR4-NOT complex which results in different pathways for translational repression and mRNA deadenylation.