Structure of Shroom domain 2 reveals a three-segmented coiled-coil required for dimerization, Rock binding, and apical constriction.
Structure of Shroom domain 2 reveals a three-segmented coiled-coil required for dimerization, Rock binding, and apical constriction.
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DOI：
10.1091/mbc.e11-11-0937
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发表时间：
2012-06
影响因子：
3.3
通讯作者：
VanDemark AP
中科院分区：
文献类型：
--
作者：
Mohan S;Rizaldy R;Das D;Bauer RJ;Heroux A;Trakselis MA;Hildebrand JD;VanDemark AP
Shrm SD2 区域包含一个核心，该核心采用 Rock 结合所需的新型三段二聚体。确定了对 Rock 结合、ppMLC 水平和收缩细胞骨架网络形成至关重要的保守界面。该复合物可能是四聚体，这表明 SD2 内的构象变化可能是在 Rock 结合时发生的。 Shroom (Shrm) 蛋白是动物发育过程中细胞形状和组织形态的重要调节因子，通过直接与 Rho 激酶 (Rock) 的卷曲螺旋区域相互作用发挥作用。 Shrm-Rock 相互作用足以指导 Rock 亚细胞定位以及随后在确定的亚细胞区域中收缩肌动球蛋白网络的组装。然而，目前尚不清楚 Shrm-Rock 相互作用如何在分子水平上受到调节。为了开始研究这个问题，我们介绍了 Shrm 结构域 2 (SD2) 的结构，它介导与 Rock 的相互作用，并且是 Shrm 功能所必需的。 SD2 是一种具有内部对称性的独特三段二聚体，我们鉴定了表面和二聚化界面内的保守残基，这些残基是 Rock-Shrm 相互作用和体内 Shrm 活性所需的。我们进一步表明，这些残基在脊椎动物和无脊椎动物的 Shroom 蛋白中都至关重要，表明 Shrm-Rock 信号模块在功能和分子上都是保守的。 Shrm SD2 的结构和生化分析表明，它与 RhoA 等其他 Rock 激活剂不同，并为 Rock 介导的收缩肌动球蛋白网络组装建立了新的范例。
The Shrm SD2 region contains a core that adopts a novel three-segmented dimer required for Rock binding. Conserved interfaces critical for Rock binding, ppMLC levels, and the formation of contractile cytoskeletal networks are identified. The complex is likely tetrameric, which suggests that conformational changes within SD2 are likely upon Rock binding. Shroom (Shrm) proteins are essential regulators of cell shape and tissue morphology during animal development that function by interacting directly with the coiled-coil region of Rho kinase (Rock). The Shrm–Rock interaction is sufficient to direct Rock subcellular localization and the subsequent assembly of contractile actomyosin networks in defined subcellular locales. However, it is unclear how the Shrm–Rock interaction is regulated at the molecular level. To begin investigating this issue, we present the structure of Shrm domain 2 (SD2), which mediates the interaction with Rock and is required for Shrm function. SD2 is a unique three-segmented dimer with internal symmetry, and we identify conserved residues on the surface and within the dimerization interface that are required for the Rock–Shrm interaction and Shrm activity in vivo. We further show that these residues are critical in both vertebrate and invertebrate Shroom proteins, indicating that the Shrm–Rock signaling module has been functionally and molecularly conserved. The structure and biochemical analysis of Shrm SD2 indicate that it is distinct from other Rock activators such as RhoA and establishes a new paradigm for the Rock-mediated assembly of contractile actomyosin networks.