Activation of Arp2/3 complex-dependent actin polymerization by plant proteins distantly related to Scar/WAVE
Activation of Arp2/3 complex-dependent actin polymerization by plant proteins distantly related to Scar/WAVE
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DOI：
10.1073/pnas.0407392101
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发表时间：
2004-11-16
影响因子：
11.1
通讯作者：
Smith, LG
中科院分区：
文献类型：
--
作者：
Frank, M;Egile, C;Smith, LG
Arp 2/3复合物是一种高度保守的肌动蛋白聚合成核因子，在真核细胞肌动蛋白动力学调控中起着关键作用。在动物细胞和酵母中，Wiskott-Aldrich综合征蛋白（WASP）/cAMP受体抑制因子（Scar）/WASP家族verprolin同源（WAVE）家族蛋白激活Arp 2/3复合物以响应局部信号。与其他真核生物一样，植物也具有Arp 2/3复合体，最近已被证明在F-肌动蛋白组织和细胞形态发生中起重要作用。然而，Arp 2/3复合物的激活剂尚未在植物中鉴定，植物缺乏WASP/Scar/WAVE家族蛋白的明显同源物。在这里，我们确定了一个家庭的疤痕/波相关的植物Arp 2/3激活剂。与Scar/WAVE蛋白一样，在拟南芥中鉴定的四种蛋白（AtSCAR 1至AtSCAR 4）和在玉米中鉴定的一种蛋白（ZmSCAR 1）具有C-末端WASP同源性2（WH 2）/酸性（WA）-verprolin同源性/cofilin同源性/酸性（VCA）样结构域，我们表明其可以激活牛Arp 2/3复合物。在它们的N末端，AtSCAR 1至ATSCAR 4，沿着与在其C末端缺少VCA/WA样结构域的第五种蛋白（At 4g 18600）一起，与Scar/WAVE家族蛋白的N末端Scar同源结构域相关。基因表达模式的分析表明，功能冗余theAtSCAR家族的成员。全长AtSCAR 1和ATSCAR 3蛋白及其Scar同源结构域在体外与AtBRICK 1（AtBRK 1）结合，AtBRK 1是HSPC 300的拟南芥同源物，HSPC 300是一种WAVE结合蛋白，最近被鉴定为涉及Scar/WAVE活性调节的复合物的组分。因此，AtSCAR蛋白很可能与AtBRK 1以及WAVE复合物组分的其他拟南芥同源物一起发挥作用，以调节Arp 2，3复合物在体内的激活。
The Arp2/3 complex, a highly conserved nucleator of F-actin polymerization, plays a key role in the regulation of actin dynamics eukaryotic cells. In animal cells and yeasts, Wiskott-Aldrich Syndrome protein (WASP)/suppressor of cAMP receptor (Scar)/WASP family verprolin homologous (WAVE) family proteins activate the Arp2/3 complex in response to localized cues. Like other eukaryotes, plants have an Arp2/3 complex, which has recently been shown to play an important role in F-actin organization and cell morphogenesis. However, no activators of the Arp2/3 complex have been identified in plants, which lack obvious homologs of WASP/Scar/WAVE family proteins. Here, we identify a family of Scar/WAVE-related plant Arp2/3 activators. Like Scar/WAVE proteins, four proteins identified in Arabidopsis thaliana (AtSCAR1 to AtSCAR4) and one in maize (ZmSCAR1) have a C-terminal WASP homology 2 (WH2)/acidic (WA)-verprolin homology/cofilin homology/acidic (VCA)-like domain, which we show can activate the bovine Arp2/3 complex. At their N termini, AtSCAR1 to ATSCAR4, along with a fifth protein lacking a VCA/WA-like domain at its C terminus (At4g18600), are related to the N-terminal Scar homology domains of Scar/WAVE family proteins. Analysis of gene expression patterns suggests functional redundancy among members of theAtSCAR family. Full-length AtSCAR1 and ATSCAR3 proteins and their Scar homology domains bind in vitro to AtBRICK 1 (AtBRK1), the Arabidopsis homolog of HSPC300, a WAVE-binding protein recently identified as a component of a complex implicated in the regulation of Scar/WAVE activity. Thus, AtSCAR proteins are likely to function in association with AtBRK1, and perhaps other Arabidopsis homologs of WAVE complex components, to regulate activation of the Arp2,3 complex in vivo.