Phosphatidylinositol 3-phosphate (PI(3)P) levels in Plasmodium falciparum correlate with tolerance to cellular stresses caused by artemisinin and environmental factors. However, PI(3)P function during the Plasmodium stress response was unknown. Here, we used PI3K inhibitors and antimalarial agents to examine the importance of PI(3)P under thermal conditions recapitulating malarial fever. Live cell microscopy using chemical and genetic reporters revealed that PI(3)P stabilizes the digestive vacuole (DV) under heat stress. We demonstrate that heat-induced DV destabilization in PI(3)P-deficient P. falciparum precedes cell death and is reversible after withdrawal of the stress condition and the PI3K inhibitor. A chemoproteomic approach identified PfHsp70-1 as a PI(3)P-binding protein. An Hsp70 inhibitor and knockdown of PfHsp70-1 phenocopy PI(3)P-deficient parasites under heat shock. Furthermore, PfHsp70-1 downregulation hypersensitizes parasites to heat shock and PI3K inhibitors. Our findings underscore a mechanistic link between PI(3)P and PfHsp70-1 and present a novel PI(3)P function in DV stabilization during heat stress.

中文翻译：

---

磷脂酰肌醇 3-磷酸和 Hsp70 保护恶性疟原虫免受热诱导的细胞死亡

恶性疟原虫中的磷脂酰肌醇 3-磷酸 (PI(3)P) 水平与对青蒿素和环境因素引起的细胞应激的耐受性相关。然而，在疟原虫应激反应过程中 PI(3)P 函数是未知的。在这里，我们使用 PI3K 抑制剂和抗疟药来检查 PI(3)P 在重现疟疾热的热条件下的重要性。使用化学和遗传记者的活细胞显微镜检查显示 PI(3)P 在热应激下稳定消化液泡 (DV)。我们证明了 PI(3)P 缺陷型恶性疟原虫中的热诱导 DV 不稳定先于细胞死亡，并且在退出应激条件和 PI3K 抑制剂后是可逆的。化学蛋白质组学方法将 PfHsp70-1 鉴定为 PI(3)P 结合蛋白。热休克下 Hsp70 抑制剂和 PfHsp70-1 表型 PI(3)P 缺陷寄生虫的敲低。此外，PfHsp70-1 下调使寄生虫对热休克和 PI3K 抑制剂过敏。我们的研究结果强调了 PI(3)P 和 PfHsp70-1 之间的机械联系，并在热应激期间在 DV 稳定中呈现了一种新的 PI(3)P 功能。