Critical conformational changes in the Arp2/3 complex are induced by nucleotide and nucleation promoting factor
Critical conformational changes in the Arp2/3 complex are induced by nucleotide and nucleation promoting factor
复制标题
DOI：
10.1016/j.molcel.2004.09.018
复制
发表时间：
2004-10-22
期刊：
影响因子：
16
通讯作者：
Welch, MD
中科院分区：
文献类型：
--
作者：
Goley, ED;Rodenbusch, SE;Welch, MD
Arp2/3复合体的肌动蛋白核化和分支受到激活因子的严格调控。然而，Arp2/3复合体的激活机制尚不清楚。我们用荧光共振能量转移(FRET)研究了Arp2/3复合体在激活过程中的构象动力学。我们证明核苷酸结合促进了复合体的实质性构象变化，不同的构象取决于结合的核苷酸。与每个Arp的核苷酸结合是活性的关键，并与成核促进因子(NPF)结合。Wiskott-Aldrich综合征蛋白(WASP)家族NPF的结合诱导了Arp2/3复合体的进一步构象重组，促进这种构象重组的能力与激活效率有关。利用与WASP的肌动蛋白结合域融合的Arp2/3复合体，我们证实了NPF诱导的构象变化是激活的关键，并且WASP的肌动蛋白和Arp2/3结合活性是可分离的，但独立地是活性所必需的。
Actin nucleation and branching by the Arp2/3 complex is tightly regulated by activating factors. However, the mechanism of Arp2/3 complex activation remains unclear. We used fluorescence resonance energy transfer (FRET) to probe the conformational dynamics of the Arp2/3 complex accompanying its activation. We demonstrate that nucleotide binding promotes a substantial conformational change in the complex, with distinct conformations depending on the bound nucleotide. Nucleotide binding to each Arp is critical for activity and is coupled to nucleation promoting factor (NPF) binding. The binding of Wiskott-Aldrich syndrome protein (WASP) family NPFs induces further conformational reorganization of the Arp2/3 complex, and the ability to promote this conformational reorganization correlates with activation efficiency. Using an Arp2/3 complex that is fused to the actin binding domain of WASP, we confirm that the NPF-induced conformational change is critical for activation, and that the actin and Arp2/3 binding activities of WASP are separable, but are independently essential for activity.