Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
EMBO J. 2021 Aug 16;40(16):e107247. doi: 10.15252/embj.2020107247. Epub 2021 May 25.
Malaria parasites contain an essential organelle called the apicoplast that houses metabolic pathways for fatty acid, heme, isoprenoid, and iron-sulfur cluster synthesis. Surprisingly, malaria parasites can survive without the apicoplast as long as the isoprenoid precursor isopentenyl pyrophosphate (IPP) is supplemented in the growth medium, making it appear that isoprenoid synthesis is the only essential function of the organelle in blood-stage parasites. In the work described here, we localized an enzyme responsible for coenzyme A synthesis, DPCK, to the apicoplast, but we were unable to delete DPCK, even in the presence of IPP. However, once the endogenous DPCK was complemented with the E. coli DPCK (EcDPCK), we were successful in deleting it. We were then able to show that DPCK activity is required for parasite survival through knockdown of the complemented EcDPCK. Additionally, we showed that DPCK enzyme activity remains functional and essential within the vesicles present after apicoplast disruption. These results demonstrate that while the apicoplast of blood-stage P. falciparum parasites can be disrupted, the resulting vesicles remain biochemically active and are capable of fulfilling essential functions.
疟原虫含有一种必需的细胞器，称为质体，它容纳脂肪酸、血红素、异戊二烯和铁硫簇合成的代谢途径。令人惊讶的是，疟原虫在没有质体的情况下也能存活，只要在生长培养基中补充异戊烯焦磷酸（IPP），这使得异戊二烯合成似乎成为血期寄生虫细胞器的唯一必需功能。在本文所述的工作中，我们将负责辅酶 A 合成的酶 DPCK 定位到质体中，但我们无法删除 DPCK，即使在存在 IPP 的情况下也是如此。然而，一旦用大肠杆菌 DPCK（EcDPCK）补充了内源性 DPCK，我们就成功地删除了它。然后，我们通过敲低互补的 EcDPCK 证明了 DPCK 活性是寄生虫存活所必需的。此外，我们还表明，DPCK 酶活性在质体破坏后存在的囊泡中仍然保持功能和必需。这些结果表明，虽然疟原虫血期 P. falciparum 的质体可以被破坏，但由此产生的囊泡仍然具有生物化学活性，并且能够发挥必需的功能。
