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Self-activating G protein α subunits engage seven-transmembrane regulator of G protein signaling (RGS) proteins and a Rho guanine nucleotide exchange factor effector in the amoeba Naegleria fowleri
Journal of Biological Chemistry ( IF 4.0 ) Pub Date : 2022-06-20 , DOI: 10.1016/j.jbc.2022.102167
Dustin E Bosch 1 , William R Jeck 2 , David P Siderovski 3
Affiliation  

The free-living amoeba Naegleria fowleri is a causative agent of primary amoebic meningoencephalitis and is highly resistant to current therapies, resulting in mortality rates >97%. As many therapeutics target G protein–centered signal transduction pathways, further understanding the functional significance of G protein signaling within N. fowleri should aid future drug discovery against this pathogen. Here, we report that the N. fowleri genome encodes numerous transcribed G protein signaling components, including G protein–coupled receptors, heterotrimeric G protein subunits, regulator of G protein signaling (RGS) proteins, and candidate Gα effector proteins. We found N. fowleri Gα subunits have diverse nucleotide cycling kinetics; Nf Gα5 and Gα7 exhibit more rapid nucleotide exchange than GTP hydrolysis (i.e., “self-activating” behavior). A crystal structure of Nf Gα7 highlights the stability of its nucleotide-free state, consistent with its rapid nucleotide exchange. Variations in the phosphate binding loop also contribute to nucleotide cycling differences among Gα subunits. Similar to plant G protein signaling pathways, N. fowleri Gα subunits selectively engage members of a large seven-transmembrane RGS protein family, resulting in acceleration of GTP hydrolysis. We show Nf Gα2 and Gα3 directly interact with a candidate Gα effector protein, RGS-RhoGEF, similar to mammalian Gα12/13 signaling pathways. We demonstrate Nf Gα2 and Gα3 each engage RGS-RhoGEF through a canonical Gα/RGS domain interface, suggesting a shared evolutionary origin with G protein signaling in the enteric pathogen Entamoeba histolytica. These findings further illuminate the evolution of G protein signaling and identify potential targets of pharmacological manipulation in N. fowleri.



中文翻译:

自激活 G 蛋白 α 亚基参与 G 蛋白信号 (RGS) 蛋白的七跨膜调节剂和福氏纳格列虫变形虫中的 Rho 鸟嘌呤核苷酸交换因子效应器

自由生活的阿米巴Naegleria fowleri是原发性阿米巴脑膜脑炎的病原体,对目前的治疗具有高度耐药性,导致死亡率 >97%。由于许多治疗剂针对以 G 蛋白为中心的信号转导通路,因此进一步了解福氏猪瘟内 G 蛋白信号传导的功能意义应​​该有助于未来发现针对这种病原体的药物。在这里,我们报告N. fowleri基因组编码许多转录的 G 蛋白信号成分,包括 G 蛋白偶联受体、异源三聚体 G 蛋白亚基、G 蛋白信号 (RGS) 蛋白调节因子和候选 Gα 效应蛋白。我们发现了N. fowleriGα亚基具有不同的核苷酸循环动力学;Nf Gα5 和 Gα7 表现出比 GTP 水解更快的核苷酸交换(“自激活”行为)。Nf Gα7 的晶体结构突出了其无核苷酸状态的稳定性,与其快速的核苷酸交换一致。磷酸结合环的变化也有助于 Gα 亚基之间的核苷酸循环差异。与植物 G 蛋白信号通路类似,福氏猪笼草Gα 亚基选择性地参与大型七跨膜 RGS 蛋白家族的成员,从而加速 GTP 水解。我们展示了 Nf Gα2 和 Gα3 直接与候选 Gα 效应蛋白 RGS-RhoGEF 相互作用,类似于哺乳动物 Gα 12/13信号通路。我们证明 Nf Gα2 和 Gα3 均通过规范的 Gα/RGS 结构域界面与 RGS-RhoGEF 结合,这表明肠道病原体溶组织内阿米巴中的 G 蛋白信号传导具有共同的进化起源。这些发现进一步阐明了 G 蛋白信号传导的演变,并确定了福氏猪瘟中药理学操作的潜在目标。

更新日期:2022-06-20
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