Formin-1 protein associates with microtubules through a peptide domain encoded by exon-2.
Formin-1 protein associates with microtubules through a peptide domain encoded by exon-2.
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DOI：
10.1016/j.yexcr.2005.12.035
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发表时间：
2006-04
影响因子：
3.7
通讯作者：
Fen Zhou;P. Leder;Stuart S. Martin
中科院分区：
文献类型：
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作者：
Fen Zhou;P. Leder;Stuart S. Martin
福尔明家族蛋白协调肌动蛋白丝和微管。福尔明结合和调节肌动蛋白细胞骨架的机制最近已得到很好的确定。然而，福明协调肌动蛋白丝和微管的分子机制仍然知之甚少。我们在此证明，Formin-1 蛋白 (Fmn1-Ib) 的 Isoform-Ib 通过与已知肌动蛋白结合域物理分离的蛋白质结构域与微管结合。当在 NIH3T3 成纤维细胞中低水平表达时，Fmn1-Ib 蛋白定位于细胞质丝，诺考达唑破坏证实为间期微管。 Fmn1-Ib 的一系列渐进突变体表明，外显子 2 的缺失导致微管解离，并与肌动蛋白膜褶皱产生更强的关联。外显子 2 编码的肽在体外结合纯化的微管蛋白，并且也足以将 GFP 定位到微管。 Exon-2 不包含任何已知的 formin 同源结构域。外显子5、7、8、FH1结构域或FH2结构域的缺失不影响微管结合。因此，我们的结果表明 Fmn1-Ib 的外显子 2 编码一种新型微管结合肽。由于福尔明蛋白通过 FH1 和 FH2 结构域与肌动蛋白丝结合，因此通过该外显子 2 编码结构域与间期微管结合提供了一种新机制，Fmn1-Ib 可以通过该机制协调肌动蛋白丝和微管。
Formin family proteins coordinate actin filaments and microtubules. The mechanisms by which formins bind and regulate the actin cytoskeleton have recently been well defined. However, the molecular mechanism by which formins coordinate actin filaments and microtubules remains poorly understood. We demonstrate here that Isoform-Ib of the Formin-1 protein (Fmn1-Ib) binds to microtubules via a protein domain that is physically separated from the known actin-binding domains. When expressed at low levels in NIH3T3 fibroblasts, Fmn1-Ib protein localizes to cytoplasmic filaments that nocodazole disruption confirmed as interphase microtubules. A series of progressive mutants of Fmn1-Ib demonstrated that deletion of exon-2 caused dissociation from microtubules and a stronger association with actin membrane ruffles. The exon-2-encoded peptide binds purified tubulin in vitro and is also sufficient to localize GFP to microtubules. Exon-2 does not contain any known formin homology domains. Deletion of exon 5, 7, 8, the FH1 domain or FH2 domain did not affect microtubule binding. Thus, our results indicate that exon-2 of Fmn1-Ib encodes a novel microtubule-binding peptide. Since formin proteins associate with actin filaments through the FH1 and FH2 domains, binding to interphase microtubules through this exon-2-encoded domain provides a novel mechanism by which Fmn1-Ib could coordinate actin filaments and microtubules.