Phospho-dependent and phospho-independent interactions of the helicase UPF1 with the NMD factors SMG5-SMG7 and SMG6.
Phospho-dependent and phospho-independent interactions of the helicase UPF1 with the NMD factors SMG5-SMG7 and SMG6.
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DOI：
10.1093/nar/gku578
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发表时间：
2014-08
影响因子：
14.9
通讯作者：
Conti E
中科院分区：
文献类型：
--
作者：
Chakrabarti S;Bonneau F;Schüssler S;Eppinger E;Conti E
无义介导的mRNA衰变（NMD）是一种真核生物的监视途径，它识别具有提前终止密码子的mRNA并靶向它们以使其快速降解。以往研究的证据表明UPF 1是NMD的核心因素。在人类细胞中，SMG 1激酶在N-末端和C-末端尾部磷酸化UPF 1，进而允许NMD因子SMG 5、SMG 6和SMG 7的募集。为了了解分子机制，我们使用纯化的组分在体外重述了NMD的这些步骤。我们发现，一个短的C-末端片段的磷酸化UPF 1含有最后两个丝氨酸-谷氨酰胺基序被识别的异源二聚体的SMG 5和SMG 7 14-3-3样蛋白。相比之下，SMG 6 14-3-3样结构域是单体。晶体结构表明，SMG 6 14-3-3-like结构域的磷酸丝氨酸结合位点与SMG 5相似，可以介导与UPF 1的弱磷酸依赖性相互作用。SMG 6-UPF 1的主要相互作用由SMG 6的14-3-3样结构域边界的低复杂性区域以及UPF 1的解旋酶结构域和C末端尾部介导。这种相互作用不依赖于磷酸化。我们的研究表明，SMG 5-SMG 7和SMG 6表现出不同的和非重叠的UPF 1识别模式，从而指出在整合复杂的NMD相互作用网络的区别作用。
Nonsense-mediated mRNA decay (NMD) is a eukaryotic surveillance pathway that recognizes mRNAs with premature stop codons and targets them for rapid degradation. Evidence from previous studies has converged on UPF1 as the central NMD factor. In human cells, the SMG1 kinase phosphorylates UPF1 at the N-terminal and C-terminal tails, in turn allowing the recruitment of the NMD factors SMG5, SMG6 and SMG7. To understand the molecular mechanisms, we recapitulated these steps of NMD in vitro using purified components. We find that a short C-terminal segment of phosphorylated UPF1 containing the last two Ser-Gln motifs is recognized by the heterodimer of SMG5 and SMG7 14–3–3-like proteins. In contrast, the SMG6 14–3–3-like domain is a monomer. The crystal structure indicates that the phosphoserine binding site of the SMG6 14–3–3-like domain is similar to that of SMG5 and can mediate a weak phospho-dependent interaction with UPF1. The dominant SMG6–UPF1 interaction is mediated by a low-complexity region bordering the 14–3–3-like domain of SMG6 and by the helicase domain and C-terminal tail of UPF1. This interaction is phosphorylation independent. Our study demonstrates that SMG5–SMG7 and SMG6 exhibit different and non-overlapping modes of UPF1 recognition, thus pointing at distinguished roles in integrating the complex NMD interaction network.
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影响因子：
14.9
作者：
Fiorini F;Boudvillain M;Le Hir H
通讯作者：
Le Hir H
DOI：
10.1073/pnas.1000993107
发表时间：
2010-06-01
影响因子：
11.1
作者：
Buchwald, Gretel;Ebert, Judith;Conti, Elena
通讯作者：
Conti, Elena
DOI：
10.1107/s0907444904019158
发表时间：
2004-12-01
影响因子：
2.2
作者：
Emsley, P;Cowtan, K
通讯作者：
Cowtan, K
影响因子：
4.5
作者：
Bhattacharya, A;Czaplinski, K;Peltz, SW
通讯作者：
Peltz, SW
影响因子：
4.8
作者：
Denning, G;Jamieson, L;Fields, AP
通讯作者：
Fields, AP