cGMP signaling is one of the master regulators of diverse functions in eukaryotes; however, its architecture and functioning in protozoans remain poorly understood. Herein, we report an exclusive guanylate cyclase coupled with N-terminal P4-ATPase in a common parasitic protist, Toxoplasma gondii This bulky protein (477-kD), termed TgATPase_P-GC to fairly reflect its envisaged multifunctionality, localizes in the plasma membrane at the apical pole of the parasite, whereas the corresponding cGMP-dependent protein kinase (TgPKG) is distributed in the cytomembranes. TgATPase_P-GC is refractory to genetic deletion, and its CRISPR/Cas9-assisted disruption aborts the lytic cycle of T. gondii Besides, Cre/loxP-mediated knockdown of TgATPase_P-GC reduced the synthesis of cGMP and inhibited the parasite growth due to impairments in the motility-dependent egress and invasion events. Equally, repression of TgPKG by a similar strategy recapitulated phenotypes of the TgATPase_P-GC-depleted mutant. Notably, despite a temporally restricted function, TgATPase_P-GC is expressed constitutively throughout the lytic cycle, entailing a post-translational regulation of cGMP signaling. Not least, the occurrence of TgATPase_P-GC orthologs in several other alveolates implies a divergent functional repurposing of cGMP signaling in protozoans, and offers an excellent drug target against the parasitic protists.

中文翻译：

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致病原生物中具有鸟苷酸环化酶和P4-ATPase结构域的异常且重要的蛋白质。

cGMP信号是真核生物中各种功能的主要调节子之一。然而，它的结构和在原生动物中的功能仍然知之甚少。在本文中，我们报道了一个共同的寄生虫原生动物弓形虫中唯一的鸟苷酸环化酶与N末端P4-ATPase偶联。这种庞大的蛋白质（477-kD）被称为Tg ATPase _P -GC，可以公平反映其设想的多功能性，位于血浆中膜在寄生虫的顶极，而相应的cGMP依赖性蛋白激酶（Tg PKG）分布在细胞膜中。Tg ATPase _P -GC难于遗传缺失，其CRISPR / Cas9辅助破坏中止了Tg ATPase _P -GC的裂解周期。弓形虫此外，的酶Cre / loxP位介导的敲低Tg的ATP酶_P -GC减少cGMP的合成和抑制寄生虫生长由于在蠕动依赖性出口和入侵事件损害。同样地，通过类似策略抑制Tg PKG概括了Tg ATPase _P -GC耗尽突变体的表型。值得注意的是，尽管功能受到时间限制，但Tg ATPase _P -GC在整个裂解周期中均组成性表达，这意味着cGMP信号的翻译后调控。尤其重要的是，Tg ATPase _P的发生-GC直向同源物在其他几种肺泡中暗示原生动物中cGMP信号的功能不同，并提供了针对寄生虫原生生物的出色药物靶标。