Small-GTPase-Associated Signaling by the Guanine Nucleotide Exchange Factors CpDock180 and CpCdc24, the GTPase Effector CpSte20, and the Scaffold Protein CpBem1 in Claviceps purpurea
Small-GTPase-Associated Signaling by the Guanine Nucleotide Exchange Factors CpDock180 and CpCdc24, the GTPase Effector CpSte20, and the Scaffold Protein CpBem1 in Claviceps purpurea
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DOI：
10.1128/ec.00332-13
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发表时间：
2014-04-01
期刊：
影响因子：
--
通讯作者：
Tudzynski, Paul
中科院分区：
文献类型：
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作者：
Herrmann, Andrea;Tillmann, Britta A. M.;Tudzynski, Paul
Rho 亚家族的单体 GTP 酶是多种生物体中极性生长和 NADPH (Nox) 信号传导的重要介质。这些途径影响麦角菌感染宿主植物的能力。 GTP 酶调节剂有助于核苷酸加载循环，这对于 GTP 酶的正常功能至关重要。支架蛋白聚集 GTP 酶复合物以促进正常功能。鸟嘌呤核苷酸交换因子 (GEF) CpCdc24 和 CpDock180 通过触发 GTPase 的核苷酸交换来激活 GTPase 信号传导。在这里，我们表明 CpCdc24 对 Rac 和 Cdc42 同源物具有核苷酸交换活性。 GEF 部分共享 GTP 酶的细胞分布，并与假定的上游 GTP 酶 CpRas1 相互作用。相互作用研究表明，由支架蛋白 CpBem1 介导的高级蛋白复合物的形成。除了 GTPase 和 GEF 之外，这些复合物还包含 GTPase 效应子 CpSte20 和 CpCla4，以及调节蛋白 CpNoxR。功能特征表明 CpCdc24 主要在极性方面发挥作用，而 CpDock180 则参与应激耐受机制。这些发现表明小 GTP 酶复合物的动态形成，并改进了 C. purpurea 中 GTP 酶相关信号传导的模型。
Monomeric GTPases of the Rho subfamily are important mediators of polar growth and NADPH (Nox) signaling in a variety of organisms. These pathways influence the ability of Claviceps purpurea to infect host plants. GTPase regulators contribute to the nucleotide loading cycle that is essential for proper functionality of the GTPases. Scaffold proteins gather GTPase complexes to facilitate proper function. The guanine nucleotide exchange factors (GEFs) CpCdc24 and CpDock180 activate GTPase signaling by triggering nucleotide exchange of the GTPases. Here we show that CpCdc24 harbors nucleotide exchange activity for both Rac and Cdc42 homologues. The GEFs partly share the cellular distribution of the GTPases and interact with the putative upstream GTPase CpRas1. Interaction studies show the formation of higher-order protein complexes, mediated by the scaffold protein CpBem1. Besides the GTPases and GEFs, these complexes also contain the GTPase effectors CpSte20 and CpCla4, as well as the regulatory protein CpNoxR. Functional characterizations suggest a role of CpCdc24 mainly in polarity, whereas CpDock180 is involved in stress tolerance mechanisms. These findings indicate the dynamic formation of small GTPase complexes and improve the model for GTPase-associated signaling in C. purpurea.