The regulation of mDia1 by autoinhibition and its release by Rho•GTP
The regulation of mDia1 by autoinhibition and its release by Rho•GTP
复制标题
DOI：
10.1038/sj.emboj.7600879
复制
发表时间：
2005-12-07
期刊：
影响因子：
11.4
通讯作者：
Wittinghofer, A
中科院分区：
文献类型：
--
作者：
Lammers, M;Rose, R;Wittinghofer, A
福明通过福明同源结构域 1 和 2 诱导无支化肌动蛋白丝的成核和聚合。透明相关福明 (Drfs) 受位于氨基末端（N 末端）区域的 RhoGTPase 结合结构域和羧基末端透明自动调节结构域 (DAD) 的调节，其相互作用稳定了 自抑制非活性构象。活性 Rho 的结合释放 DAD 并激活 mDia 的催化活性。在这里，我们报告了 DAD 与 mDia1 (mDia(N)) 的调节性 N 末端的相互作用及其通过 Rho 中心点 GTP 的释放。我们定义了紧密结合所需的元素，并通过 X 射线晶体学解析了 mDiaN 结构和 DAD 之间复合物的三维结构。核心 DAD 区域是一个 α 螺旋肽，它主要通过疏水相互作用结合在 mDiaN 最高度保守的区域。该结构表明释放自抑制的两步机制，其中 Rho 中心点 GTP 尽管具有部分不重叠的结合位点，但通过离子排斥和空间冲突取代 DAD。我们发现 Rho 中心点 GTP 加速了 DAD 从 mDia(N) 中心点 DAD 复合物的解离。
Formins induce the nucleation and polymerisation of unbranched actin filaments via the formin-homology domains 1 and 2. Diaphanous-related formins (Drfs) are regulated by a RhoGTPase-binding domain situated in the amino-terminal (N-terminal) region and a carboxyterminal Diaphanous-autoregulatory domain (DAD), whose interaction stabilises an autoinhibited inactive conformation. Binding of active Rho releases DAD and activates the catalytic activity of mDia. Here, we report on the interaction of DAD with the regulatory N-terminus of mDia1 (mDia(N)) and its release by Rho center dot GTP. We have defined the elements required for tight binding and solved the three-dimensional structure of a complex between an mDiaN construct and DAD by X-ray crystallography. The core DAD region is an a-helical peptide, which binds in the most highly conserved region of mDiaN using mainly hydrophobic interactions. The structure suggests a two-step mechanism for release of autoinhibition whereby Rho center dot GTP, although having a partially nonoverlapping binding site, displaces DAD by ionic repulsion and steric clashes. We show that Rho center dot GTP accelerates the dissociation of DAD from the mDia(N)center dot DAD complex.