Structural Principles in Robo Activation and Auto-inhibition
Structural Principles in Robo Activation and Auto-inhibition
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DOI：
10.1016/j.cell.2019.02.004
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发表时间：
2019-04-04
期刊：
影响因子：
64.5
通讯作者：
Opatowsky, Yarden
中科院分区：
文献类型：
--
作者：
Barak, Reut;Yom-Tov, Galit;Opatowsky, Yarden
适当的大脑功能需要高精度的神经元扩展和布线，这一过程由跨膜Roundabout（Robo）受体家族及其Slit配体控制。尽管它们非常重要，但Robos从“关闭”状态切换到“打开”状态的分子机制仍然不清楚。在这里，我们报道了完整的人Robo 2胞外域（结构域D1-8）的3.6（A）过点晶体结构。我们证明了通过D4的Robo顺式二聚化通过hRobo 1、2和3是保守的，并且C. elegans同源物SAX-3，并且是SAX-3在体内功能所必需的。该结构揭示了防止过早激活的两个水平的自抑制：（1）D4二聚化界面的顺式阻断和（2）固定D4阻断构象的相对Robo受体之间的反式相互作用。在小鼠原代神经元和C. elegans支持自动抑制模型。这些结果表明，Slit刺激主要驱动二聚化和活化所需的Robo自抑制的释放。
Proper brain function requires high-precision neuronal expansion and wiring, processes controlled by the transmembrane Roundabout (Robo) receptor family and their Slit ligands. Despite their great importance, the molecular mechanism by which Robos' switch from "off" to "on" states remains unclear. Here, we report a 3.6 (A) over dot crystal structure of the intact human Robo2 ectodomain (domains D1-8). We demonstrate that Robo cis dimerization via D4 is conserved through hRobo1, 2, and 3 and the C. elegans homolog SAX-3 and is essential for SAX-3 function in vivo. The structure reveals two levels of auto-inhibition that prevent premature activation: (1) cis blocking of the D4 dimerization interface and (2) trans interactions between opposing Robo receptors that fasten the D4-blocked conformation. Complementary experiments in mouse primary neurons and C. elegans support the auto-inhibition model. These results suggest that Slit stimulation primarily drives the release of Robo auto-inhibition required for dimerization and activation.