Analysis of the function of spire in actin assembly and its synergy with formin and profilin
Analysis of the function of spire in actin assembly and its synergy with formin and profilin
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DOI：
10.1016/j.molcel.2007.09.018
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发表时间：
2007-11-30
期刊：
影响因子：
16
通讯作者：
Carlier, Marie-France
中科院分区：
文献类型：
--
作者：
Bosch, Montserrat;Le, Kim Ho Diep;Carlier, Marie-France
Spire蛋白与Cappuccino蛋白和profilin蛋白一起，在建立卵母细胞极性的基于肌动蛋白的过程中发挥重要作用。Spire包含四个肌动蛋白结合WH 2结构域的簇。它已被证明能使肌动蛋白丝成核，并被认为能保持与它们的尖端结合。在这里，我们表明，WH 2结构域的多功能特性允许Spire隔离四个G-肌动蛋白亚基，它们在紧密的SA（4）复合物中协同结合，并在它们的倒刺末端成核、切断和覆盖细丝。Spire与倒刺末端的结合不影响倒刺末端肌动蛋白组装的热力学，但阻止了来自profilin-actin的倒刺末端生长。螺旋诱导的profilin-actin浓度的增加增强了螺旋的进行性丝组装。Spire和Profilin之间的协同作用在体外运动试验中重建，这为Spire、Profilin和profilin在卵子发生中的遗传相互作用提供了功能基础。
The Spire protein, together with the formin Cappuccino and profilin, plays an important role in actin-based processes that establish oocyte polarity. Spire contains a cluster of four actin-binding WH2 domains. It has been shown to nucleate actin filaments and was proposed to remain bound to their pointed ends. Here we show that the multifunctional character of the WH2 domains allows Spire to sequester four G-actin subunits binding cooperatively in a tight SA(4) complex and to nucleate, sever, and cap filaments at their barbed ends. Binding of Spire to barbed ends does not affect the thermodynamics of actin assembly at barbed ends but blocks barbed end growth from profilin-actin. The resulting Spire-induced increase in profilin-actin concentration enhances processive filament assembly by formin. The synergy between Spire and formin is reconstituted in an in vitro motility assay, which provides a functional basis for the genetic interplay between Spire, formin, and profilin in oogenesis.