Background:

Intracellular protein trafficking is crucial for survival of cell and proper functioning of the organelles; however, these pathways are not well studied in the malaria parasite. Its unique cellular architecture and organellar composition raise an interesting question to investigate.

Methods:

The interaction of Plasmodium falciparum Rab7 (PfRab7) with vacuolar protein sorting-associated protein 26 (PfVPS26) of retromer complex was shown by coimmunoprecipitation (co-IP). Confocal microscopy was used to show the localization of the complex in the parasite with respect to different organelles. Further chemical tools were employed to explore the role of digestive vacuole (DV) in retromer trafficking in parasite and GTPase activity of PfRab7 was examined.

Results:

PfRab7 was found to be interacting with retromer complex that assembled mostly near DV and the Golgi in trophozoites. Chemical disruption of DV by chloroquine (CQ) led to its disassembly that was further validated by using compound 5f, a heme polymerization inhibitor in the DV. PfRab7 exhibited Mg²⁺ dependent weak GTPase activity that was inhibited by a specific Rab7 GTPase inhibitor, CID 1067700, which prevented the assembly of retromer complex in P. falciparum and inhibited its growth suggesting the role of GTPase activity of PfRab7 in retromer assembly.

Conclusion:

Retromer complex was found to be interacting with PfRab7 and the functional integrity of the DV was found to be important for retromer assembly in P. falciparum.

General significance:

This study explores the retromer trafficking in P. falciparum and describes amechanism to validate DV targeting antiplasmodial molecules.

背景：

细胞内蛋白质运输对于细胞存活和细胞器的正常运转至关重要。但是，这些途径在疟疾寄生虫中并未得到很好的研究。其独特的细胞结构和细胞器组成提出了一个有趣的问题进行研究。

方法：

的相互作用恶性疟原虫RAB7（Pf的RAB7）与液泡蛋白分选相关蛋白26（Pf的Retromer Complex上的VPS26）通过免疫共沉淀（共-IP）所示。共聚焦显微镜用于显示复合物中寄生虫相对于不同细胞器的定位。进一步的化学工具被用来探索消化液泡（DV）在寄生虫的逆转录贩运中的作用，并检查了Pf Rab7的GTPase活性。

结果：

Pf Rab7被发现与逆转录复合物相互作用，后者在滋养体中主要在DV和高尔基体附近组装。氯喹（CQ）对DV的化学破坏导致其分解，这可通过在DV中使用血红素聚合抑制剂化合物5f进一步验证。Pf Rab7表现出Mg ²⁺依赖性的弱GTPase活性，该活性被特定的Rab7 GTPase抑制剂CID 1067700抑制，它阻止恶性疟原虫的逆转录复合物组装并抑制其生长，表明Pf Rab7的GTPase活性在逆转录组装中的作用。 。

结论：

发现Retromer复合物与Pf Rab7相互作用，DV的功能完整性对恶性疟原虫的Retromer组装很重要。

一般意义：

这项研究探讨了恶性疟原虫的逆转录酶贩运，并描述了用于验证针对抗疟原虫分子的DV的机制。