Interaction of the N- and C-terminal Autoregulatory Domains of FRL2 Does Not Inhibit FRL2 Activity
Interaction of the N- and C-terminal Autoregulatory Domains of FRL2 Does Not Inhibit FRL2 Activity
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DOI：
10.1074/jbc.m803156200
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发表时间：
2008-11-28
影响因子：
4.8
通讯作者：
Copeland, John W.
中科院分区：
文献类型：
--
作者：
Vaillant, Dominique C.;Copeland, Sarah J.;Copeland, John W.
福尔明同源蛋白是高度保守的细胞骨架重塑蛋白家族，以其诱导长的无分支肌动蛋白丝形成的能力而闻名。他们通过使F-肌动蛋白从头聚合成核并充当F-肌动蛋白带刺末端的“渗漏封盖器”来实现这一点，该封盖器允许丝伸长，同时拮抗封盖蛋白的功能。最近，据报道，FRL1 和 mDia2 的 FH2 结构域以及植物形式 AFH1 能够通过不同的机制结合和捆绑肌动蛋白丝。我们发现像 FRL1 一样，FRL2 和 FRL3 也能够结合和成束肌动蛋白丝。就 FRL3 而言，该活性依赖于 FH2 结构域 C 端的近端 DAD/WH2 样结构域。此外，我们发现，与其他 Diaphanous 相关的福明斯一样，FRL3 活性受到其 N 端 DID 和 C 端 DAD 之间相互作用介导的自动调节。相比之下，FRL2的DID和DAD在体内和体外也相互作用，但不抑制FRL2活性。这些数据表明，当前通过 FH2 活性的空间位阻描述 DID/DAD 自动调节的模型必须进行修改。最后，与其他福明不同，我们发现 FH2 和 FRL2 和 FRL3 的 N 端二聚化结构域能够形成异源寡聚物。
Formin homology proteins are a highly conserved family of cytoskeletal remodeling proteins best known for their ability to induce the formation of long unbranched actin filaments. They accomplish this by nucleating the de novo polymerization of F-actin and also by acting as F-actin barbed end "leaky cappers" that allow filament elongation while antagonizing the function of capping proteins. More recently, it has been reported that the FH2 domains of FRL1 and mDia2 and the plant formin AFH1 are able to bind and bundle actin filaments via distinct mechanisms. We find that like FRL1, FRL2 and FRL3 are also able to bind and bundle actin filaments. In the case of FRL3, this activity is dependent upon a proximal DAD/WH2-like domain that is found C-terminal to the FH2 domain. In addition, we show that, like other Diaphanous-related formins, FRL3 activity is subject to autoregulation mediated by the interaction between its N-terminal DID and C-terminal DAD. In contrast, the DID and DAD of FRL2 also interact in vivo and in vitro but without inhibiting FRL2 activity. These data suggest that current models describing DID/DAD autoregulation via steric hindrance of FH2 activity must be revised. Finally, unlike other formins, we find that the FH2 and N-terminal dimerization domains of FRL2 and FRL3 are able to form hetero-oligomers.