Tritschler Felix, Eulalio Ana, Helms Sigrun, Schmidt Steffen, Coles Murray, Weichenrieder Oliver, Izaurralde Elisa, Truffault Vincent
Max Planck Institute for Developmental Biology,Tübingen, Germany.
Mol Cell Biol. 2008 Nov;28(21):6695-708. doi: 10.1128/MCB.00759-08. Epub 2008 Sep 2.
Trailer Hitch (Tral or LSm15) and enhancer of decapping-3 (EDC3 or LSm16) are conserved eukaryotic members of the (L)Sm (Sm and Like-Sm) protein family. They have a similar domain organization, characterized by an N-terminal LSm domain and a central FDF motif; however, in Tral, the FDF motif is flanked by regions rich in charged residues, whereas in EDC3 the FDF motif is followed by a YjeF_N domain. We show that in Drosophila cells, Tral and EDC3 specifically interact with the decapping activator DCP1 and the DEAD-box helicase Me31B. Nevertheless, only Tral associates with the translational repressor CUP, whereas EDC3 associates with the decapping enzyme DCP2. Like EDC3, Tral interacts with DCP1 and localizes to mRNA processing bodies (P bodies) via the LSm domain. This domain remains monomeric in solution and adopts a divergent Sm fold that lacks the characteristic N-terminal alpha-helix, as determined by nuclear magnetic resonance analyses. Mutational analysis revealed that the structural integrity of the LSm domain is required for Tral both to interact with DCP1 and CUP and to localize to P-bodies. Furthermore, both Tral and EDC3 interact with the C-terminal RecA-like domain of Me31B through their FDF motifs. Together with previous studies, our results show that Tral and EDC3 are structurally related and use a similar mode to associate with common partners in distinct protein complexes.
拖车挂钩蛋白（Tral或LSm15）和去帽增强子3（EDC3或LSm16）是（L）Sm（Sm和类Sm）蛋白家族中保守的真核成员。它们具有相似的结构域组织，其特征是N端的LSm结构域和中央的FDF基序；然而，在Tral中，FDF基序两侧是富含带电残基的区域，而在EDC3中，FDF基序后面是YjeF_N结构域。我们发现，在果蝇细胞中，Tral和EDC3与去帽激活因子DCP1和DEAD盒解旋酶Me31B特异性相互作用。然而，只有Tral与翻译阻遏物CUP结合，而EDC3与去帽酶DCP2结合。与EDC3一样，Tral与DCP1相互作用，并通过LSm结构域定位于mRNA加工小体（P小体）。核磁共振分析表明，该结构域在溶液中保持单体状态，并采用一种不同的Sm折叠，缺乏特征性的N端α螺旋。突变分析表明，LSm结构域的结构完整性对于Tral与DCP1和CUP相互作用以及定位于P小体都是必需的。此外，Tral和EDC3都通过它们的FDF基序与Me31B的C端RecA样结构域相互作用。与先前的研究一起，我们的结果表明，Tral和EDC3在结构上相关，并使用相似的模式与不同蛋白质复合物中的共同伙伴结合。
