Crystal Structure of the Coiled-coil Domain of Drosophila TRIM Protein Brat
Crystal Structure of the Coiled-coil Domain of Drosophila TRIM Protein Brat
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果蝇 TRIM 蛋白 Brat 卷曲螺旋结构域的晶体结构
DOI：
10.1002/prot.25691
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Wang Wenning
中科院分区：
文献类型：
--
作者：
Liu Chunhua;Shan Zelin;Diao Jianqiao;Wen Wenyu;Wang Wenning
果蝇脑肿瘤（Drosophilabrain tumor，Brat）是TRIM蛋白超家族中的一个翻译抑制因子。在果蝇成神经细胞不对称分裂过程中，Brat通过与支架蛋白米兰达（Mira）的直接相互作用定位于基底皮质，并在细胞分裂后分离到基底节母细胞中。先前报道，Brat的卷曲螺旋（CC）和NHL结构域都是与Mira相互作用所必需的，但潜在的结构基础是难以捉摸的。在这里，我们确定了2.5 nm处Brat-CC结构域（aa 376 - 511）的晶体结构，表明Brat-CC通过非常规的CC结构形成了一个伸长的反平行二聚体。Brat-CC结构中的二聚体组装与其他TRIM蛋白中的对应物相似，但Brat-CC也表现出一些独特的结构特征。我们还表明，CC结构域不能结合米拉通过自己的，也没有孤立的NHL结构域的布拉特。相反，Brat通过CC-NHL结构域串联结合Mira，表明CC结构域的功能是以二聚体形式组装Brat-NHL，这是Mira结合所必需的。
Drosophilabrain tumor (Brat) is a translational repressor belonging to the tripartite motif (TRIM) protein superfamily. During the asymmetric division ofDrosophilaneuroblasts, Brat localizes at the basal cortex via direct interaction with the scaffolding protein Miranda (Mira), and segregates into the basal ganglion mother cells after cell division. It was previously reported that both the coiled‐coil (CC) and NHL domains of Brat are required for the interaction with Mira, but the underlying structural basis is elusive. Here, we determine the crystal structure of Brat‐CC domain (aa 376‐511) at 2.5 Å, showing that Brat‐CC forms an elongated antiparallel dimer through an unconventional CC structure. The dimeric assembly in Brat‐CC structure is similar to its counterparts in other TRIM proteins, but Brat‐CC also exhibits some distinct structural features. We also demonstrate that the CC domain could not bind Mira by its own, neither does the isolated NHL domain of Brat. Rather, Brat binds to Mira through the CC‐NHL domain tandem, indicating that the function of the CC domain is to assemble Brat‐NHL in dimeric form, which is necessary for Mira binding.