Department of Biochemistry, Max Planck Institute for Developmental Biology, D-72076 Tübingen, Germany.
European Molecular Biology Laboratory, 38042 Grenoble Cedex 9, France.
Genes Dev. 2019 Oct 1;33(19-20):1355-1360. doi: 10.1101/gad.329219.119. Epub 2019 Aug 22.
GIGYF (Grb10-interacting GYF [glycine-tyrosine-phenylalanine domain]) proteins coordinate with 4EHP (eIF4E [eukaryotic initiation factor 4E] homologous protein), the DEAD (Asp-Glu-Ala-Asp)-box helicase Me31B/DDX6, and mRNA-binding proteins to elicit transcript-specific repression. However, the underlying molecular mechanism remains unclear. Here, we report that GIGYF contains a motif necessary and sufficient for direct interaction with Me31B/DDX6. A 2.4 Å crystal structure of the GIGYF-Me31B complex reveals that this motif arranges into a coil connected to a β hairpin on binding to conserved hydrophobic patches on the Me31B RecA2 domain. Structure-guided mutants indicate that 4EHP-GIGYF-DDX6 complex assembly is required for tristetraprolin-mediated down-regulation of an AU-rich mRNA, thus revealing the molecular principles of translational repression.
GIGYF（Grb10 相互作用的 GYF [甘氨酸-酪氨酸-苯丙氨酸结构域]）蛋白与 4EHP（eIF4E [真核起始因子 4E]同源蛋白）、DEAD（Asp-Glu-Ala-Asp）盒解旋酶 Me31B/DDX6 和 mRNA 结合蛋白协同作用，引发转录物特异性抑制。然而，其潜在的分子机制仍不清楚。在这里，我们报告 GIGYF 包含一个与 Me31B/DDX6 直接相互作用所必需且充分的基序。GIGYF-Me31B 复合物的 2.4Å 晶体结构揭示了该基序在与 Me31B RecA2 结构域上保守的疏水性斑块结合时，排列成一个与β发夹相连的卷曲，形成一个卷曲。结构引导突变表明，4EHP-GIGYF-DDX6 复合物的组装是 tristetraprolin 介导的 AU 丰富 mRNA 下调所必需的，从而揭示了翻译抑制的分子原理。
