Crystal structure of human Edc3 and its functional implications
Crystal structure of human Edc3 and its functional implications
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DOI：
10.1128/mcb.00761-08
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发表时间：
2008-10-01
影响因子：
5.3
通讯作者：
Song, Haiwei
中科院分区：
文献类型：
--
作者：
Ling, Sharon H. M.;Decker, Carolyn J.;Song, Haiwei
Edc3是脱冠的增强子，作为一个支架，将mRNA核糖核蛋白聚集在一起形成p体。Edc3与mRNA脱冠机制的组成部分形成相互作用网络，并具有模块化结构域，由n端Lsm结构域、中心FDF结构域和c端YjeF-N结构域组成。我们以2.2埃的分辨率确定了n端截断的人类Edc3的晶体结构。结构表明Edc3的YjeF-N结构域具有发散的Rossmann褶皱拓扑结构，形成二聚体，这得到了溶液中沉降速度和沉降平衡分析的支持。Edc3的二聚化界面在真核生物中高度保守，尽管整个物种间序列同源性较低。基于结构的位点定向诱变揭示了二聚体是有效RNA结合、p体形成所必需的，也可能是调节酵母Rps28B mRNA所必需的，这表明Edc3的二聚体形式是mRNA降解的结构和功能单元。
Edc3 is an enhancer of decapping and serves as a scaffold that aggregates mRNA ribonucleoproteins together for P-body formation. Edc3 forms a network of interactions with the components of the mRNA decapping machinery and has a modular domain architecture consisting of an N-terminal Lsm domain, a central FDF domain, and a C-terminal YjeF-N domain. We have determined the crystal structure of the N-terminally truncated human Edc3 at a resolution of 2.2 angstrom. The structure reveals that the YjeF-N domain of Edc3 possesses a divergent Rossmann fold topology that forms a dimer, which is supported by sedimentation velocity and sedimentation equilibrium analysis in solution. The dimerization interface of Edc3 is highly conserved in eukaryotes despite the overall low sequence homology across species. Structure-based site-directed mutagenesis revealed dimerization is required for efficient RNA binding, P-body formation, and likely for regulating the yeast Rps28B mRNA as well, suggesting that the dimeric form of Edc3 is a structural and functional unit in mRNA degradation.