A conserved amphipathic helix in WASP/Scar proteins is essential for activation of Arp2/3 complex
A conserved amphipathic helix in WASP/Scar proteins is essential for activation of Arp2/3 complex
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DOI：
10.1038/nsb952
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发表时间：
2003-08-01
期刊：
影响因子：
--
通讯作者：
Rosen, MK
中科院分区：
文献类型：
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作者：
Panchal, SC;Kaiser, DA;Rosen, MK
Wiskott-Aldrich综合征蛋白（WASP）家族成员通过称为Arp2/3复合物的多蛋白组装将Rho GTPase信号通路连接到细胞骨架。WASP及其亲缘蛋白的c端VCA区（verprolin同源区、中心疏水区和酸性区）刺激Arp2/3复合体形成肌动蛋白丝分支。在这里，我们通过核磁共振谱的差异线展宽表明，来自WASP、N-WASP和Scar的VCA结构域的C（中心）和A（酸性）片段结合了Arp2/3复合物。这些蛋白的C区具有由疏水残基和精氨酸残基组成的保守序列基序。这个保守序列基序的点突变表明，它形成了一个两亲螺旋，这是激活Arp2/3复合物的生化分析所必需的。在WASP和N-WASP的自抑制结构中，该基序的关键残基通过与GTPase结合域的接触而被埋没，这表明这些残基的隔离是自抑制的一个重要方面。
Members of the Wiskott-Aldrich syndrome protein ( WASP) family link Rho GTPase signaling pathways to the cytoskeleton through a multiprotein assembly called Arp2/3 complex. The C-terminal VCA regions ( verprolin-homology, central hydrophobic, and acidic regions) of WASP and its relatives stimulate Arp2/3 complex to nucleate actin filament branches. Here we show by differential line broadening in NMR spectra that the C ( central) and A ( acidic) segments of VCA domains from WASP, N-WASP and Scar bind Arp2/3 complex. The C regions of these proteins have a conserved sequence motif consisting of hydrophobic residues and an arginine residue. Point mutations in this conserved sequence motif suggest that it forms an amphipathic helix that is required in biochemcial assays for activation of Arp2/3 complex. Key residues in this motif are buried through contacts with the GTPase binding domain in the autoinhibited structure of WASP and N-WASP, indicating that sequestration of these residues is an important aspect of autoinhibition.