The Putative Exchange Factor Gef3p Interacts with Rho3p GTPase and the Septin Ring during Cytokinesis in Fission Yeast*
The Putative Exchange Factor Gef3p Interacts with Rho3p GTPase and the Septin Ring during Cytokinesis in Fission Yeast*
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DOI：
10.1074/jbc.m114.548792
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发表时间：
2014-06
期刊：
影响因子：
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通讯作者：
Sofía Muñoz;E. Manjón;Y. Sánchez
中科院分区：
文献类型：
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作者：
Sofía Muñoz;E. Manjón;Y. Sánchez
背景：鸟嘌呤核苷酸交换因子（GEFs）调节小GTP酶的活性以控制细胞功能。结果：Gef 3 p在分裂位点与GTP酶Rho 3 p相互作用，定位于Septin环。结论：Gef 3 p/Rho 3 p模块参与了分泌途径的下游事件。意义：septins和Rho-GEFs之间的相互作用为GTP酶在胞质分裂中指导分泌提供了一种新的靶向机制。Rho家族的小GTP结合蛋白及其调节蛋白在细胞动力学肌动球蛋白环组装和胞质分裂中起核心作用。在这里，我们表明，分裂酵母鸟嘌呤核苷酸交换因子Gef 3 p与Rho 3 p在分裂位点相互作用。Gef 3 p包含一个推定的DH同源结构域和一个BAR/IMD样结构域。该蛋白定位于有丝分裂后期的分裂位点，在那里它形成了一个环，不与肌动球蛋白环（细胞动力学肌动球蛋白环）内陷收缩;相反，它分裂成一个类似于隔蛋白环的双环。Gef 3 p与septins和Mid 2 p共定位，并且其定位需要septins和Mid 2 p。Gef 3 p与Rho 3 p的GTP结合形式物理相互作用。虽然Gef 3 p不是细胞分离所必需的，但同时破坏gef 3+和Rho 3 p相互作用的蛋白质，如外囊组分Sec 8 p、网格蛋白接头复合物的亚基Apm 1 p或肌动蛋白聚合蛋白For 3 p，分别产生在分隔和极性上具有强烈缺陷的细胞。我们的研究结果表明，septins和Rho-GEFs之间的相互作用提供了一个新的靶向机制，GTP酶在胞质分裂，在这种情况下，可能有助于Rho 3 p功能的小泡拴系和小泡贩运在细胞分离的后期步骤。
Background: Guanine nucleotide exchange factors (GEFs) regulate the activity of small GTPases to control cellular functions. Results: Gef3p interacts with the GTPase Rho3p at the division site and localizes to the septin ring. Conclusion: The module Gef3p/Rho3p contributes to downstream events in the secretory pathway. Significance: The interactions between septins and Rho-GEFs provide a new targeting mechanism for GTPases to direct secretion in cytokinesis. The small GTP-binding proteins of the Rho family and its regulatory proteins play a central role in cytokinetic actomyosin ring assembly and cytokinesis. Here we show that the fission yeast guanine nucleotide exchange factor Gef3p interacts with Rho3p at the division site. Gef3p contains a putative DH homology domain and a BAR/IMD-like domain. The protein localized to the division site late in mitosis, where it formed a ring that did not constrict with actomyosin ring (cytokinetic actomyosin ring) invagination; instead, it split into a double ring that resembled the septin ring. Gef3p co-localized with septins and Mid2p and required septins and Mid2p for its localization. Gef3p interacts physically with the GTP-bound form of Rho3p. Although Gef3p is not essential for cell separation, the simultaneous disruption of gef3+ and Rho3p-interacting proteins, such as Sec8p, an exocyst component, Apm1p, a subunit of the clathrin adaptor complex or For3p, an actin-polymerizing protein, yielded cells with strong defects in septation and polarity respectively. Our results suggest that interactions between septins and Rho-GEFs provide a new targeting mechanism for GTPases in cytokinesis, in this case probably contributing to Rho3p function in vesicle tethering and vesicle trafficking in the later steps of cell separation.