Structural snapshots of the mechanism and inhibition of a guanine nucleotide exchange factor
Structural snapshots of the mechanism and inhibition of a guanine nucleotide exchange factor
复制标题
DOI：
10.1038/nature02197
复制
发表时间：
2003-12-04
期刊：
影响因子：
64.8
通讯作者：
Cherfils, J
中科院分区：
文献类型：
--
作者：
Renault, L;Guibert, B;Cherfils, J
小的GTP结合(G)蛋白被鸟嘌呤核苷酸交换因子(GEF)刺激的GDP/GTP核苷酸交换激活。小G蛋白-全球环境基金复合体的核苷酸解离涉及GDP结合的瞬时中间体，其结构从未被描述过。在真核细胞中调节细胞膜运输的小G蛋白Arf蛋白的情况下，这样的中间产物可以被天然抑制剂Brefield din A捕获，也可以通过在其GEF的Sec7结构域的催化谷氨酸上进行电荷反转来捕获。在这里，我们报道了这些中间体的晶体结构，表明Arf的膜募集和核苷酸解离是Sec7刺激的单独反应。这些反应通过Arf.GDP核心朝向Sec7催化中心的顺序旋转进行，并被Brefield din A的界面结合和通过电荷反转对GDP的无效稳定所阻止。该反应的结构特征及其抑制模式揭示了抑制小G蛋白激活的未知方法。
Small GTP-binding (G) proteins are activated by GDP/GTP nucleotide exchange stimulated by guanine nucleotide exchange factors ( GEFs). Nucleotide dissociation from small G protein - GEF complexes involves transient GDP-bound intermediates whose structures have never been described. In the case of Arf proteins, small G proteins that regulate membrane traffic in eukaryotic cells, such intermediates can be trapped either by the natural inhibitor brefeldin A or by charge reversal at the catalytic glutamate of the Sec7 domain of their GEFs. Here we report the crystal structures of these intermediates that show that membrane recruitment of Arf and nucleotide dissociation are separate reactions stimulated by Sec7. The reactions proceed through sequential rotations of the Arf.GDP core towards the Sec7 catalytic site, and are blocked by interfacial binding of brefeldin A and unproductive stabilization of GDP by charge reversal. The structural characteristics of the reaction and its modes of inhibition reveal unexplored ways in which to inhibit the activation of small G proteins.