The Rho-GEF Gef3 interacts with the septin complex and activates the GTPase Rho4 during fission yeast cytokinesis.
The Rho-GEF Gef3 interacts with the septin complex and activates the GTPase Rho4 during fission yeast cytokinesis.
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DOI：
10.1091/mbc.e14-07-1196
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发表时间：
2015-01-15
影响因子：
3.3
通讯作者：
Wu JQ
中科院分区：
文献类型：
--
作者：
Wang N;Wang M;Zhu YH;Grosel TW;Sun D;Kudryashov DS;Wu JQ
与分裂酵母中的其他六个Rho GEF不同，Gef3在胞质分裂后期与区间蛋白共定位并依赖于区间蛋白定位。Gef3与GDP-Rho4结合，并在体外加速其核苷酸交换。此外，Gef3在体内调节Rho4的活性，并在分裂酵母胞质分裂中以与Rho4相同的遗传途径调节隔膜。Rho GTP酶由Rho鸟嘌呤核苷酸交换因子(GEF)激活，是信号转导的保守分子开关，调节多种细胞过程，包括细胞极化和胞质分裂。裂殖酵母有6个Rho GTP酶(CDc42和Rho1-Rho5)和7个Rho GEF(Scd1、Rgf1-Rgf3和Gef1-Gef3)。Rho2-Rho5的GEF尚未得到明确分配。特别是，规模最小的RHO环境基金Gef3几乎没有得到研究。在这里，我们显示了Gef3与细胞赤道上的Septins共定位。Gef3在物理上与Septins和ANYLING Mid2相互作用，并依赖它们进行定位。Gef3在体外与GDP结合的Rho4共沉淀，加速了Rho4的核苷酸交换，表明Gef3是Rho4的环境基金。Gef3和Rho4在调节隔膜形成和/或细胞分离方面一直处于相同的遗传途径中。在Gef3∆细胞中，两种潜在的Rho4效应物--葡聚糖酶Eng1和AgN1-的定位异常，活性Rho4水平降低，表明Gef3参与了体内Rho4的激活。此外，活性Rho4或Eng1的过表达挽救了含有Gef3∆的突变体的分离缺陷。综上所述，我们的数据支持Gef3与Septin复合体相互作用，并激活Rho4 GTP酶作为Rho Global在分裂酵母中进行隔膜。
Unlike the six other Rho GEFs in fission yeast, Gef3 colocalizes with and depends on septins to localize during late cytokinesis. Gef3 binds to GDP-Rho4 and accelerates its nucleotide exchange in vitro. Moreover, Gef3 modulates Rho4 activity in vivo and works in the same genetic pathways as Rho4 to regulate septation in fission yeast cytokinesis. Rho GTPases, activated by Rho guanine nucleotide exchange factors (GEFs), are conserved molecular switches for signal transductions that regulate diverse cellular processes, including cell polarization and cytokinesis. The fission yeast Schizosaccharomyces pombe has six Rho GTPases (Cdc42 and Rho1–Rho5) and seven Rho GEFs (Scd1, Rgf1–Rgf3, and Gef1–Gef3). The GEFs for Rho2–Rho5 have not been unequivocally assigned. In particular, Gef3, the smallest Rho GEF, was barely studied. Here we show that Gef3 colocalizes with septins at the cell equator. Gef3 physically interacts with septins and anillin Mid2 and depends on them to localize. Gef3 coprecipitates with GDP-bound Rho4 in vitro and accelerates nucleotide exchange of Rho4, suggesting that Gef3 is a GEF for Rho4. Consistently, Gef3 and Rho4 are in the same genetic pathways to regulate septum formation and/or cell separation. In gef3∆ cells, the localizations of two potential Rho4 effectors—glucanases Eng1 and Agn1—are abnormal, and active Rho4 level is reduced, indicating that Gef3 is involved in Rho4 activation in vivo. Moreover, overexpression of active Rho4 or Eng1 rescues the septation defects of mutants containing gef3∆. Together our data support that Gef3 interacts with the septin complex and activates Rho4 GTPase as a Rho GEF for septation in fission yeast.