Isoprenoid Precursor Biosynthesis Is the Essential Metabolic Role of the Apicoplast during Gametocytogenesis in Plasmodium falciparum

Abstract

The malaria parasite harbors a relict plastid called the apicoplast and its discovery opened a new avenue for drug discovery and development due to its unusual, nonmammalian metabolism. The apicoplast is essential during the asexual intraerythrocytic and hepatic stages of the parasite, and there is strong evidence supporting its essential metabolic role during the mosquito stages of the parasite. Supply of the isoprenoid building blocks isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) is the essential metabolic function of the apicoplast during the asexual intraerythrocytic stages. However, the metabolic role of the apicoplast during gametocyte development, the malaria stages transmitted to the mosquito, remains unknown. In this study, we showed that production of IPP for isoprenoid biosynthesis is the essential metabolic function of the apicoplast during gametocytogenesis, by obtaining normal gametocytes lacking the apicoplast when supplemented with IPP. When IPP supplementation was removed early in gametocytogenesis, developmental defects were observed, supporting the essential role of isoprenoids for normal gametocytogenesis. Furthermore, mosquitoes infected with gametocytes lacking the apicoplast developed fewer and smaller oocysts that failed to produce sporozoites. This finding further supports the essential role of the apicoplast in establishing a successful infection in the mosquito vector. Our study supports isoprenoid biosynthesis as a valid drug target for development of malaria transmission-blocking inhibitors.

The apicoplast: now you see it, now you don’t

“…Apicoplast IPP synthesis is also essential for gametocytogenesis in P. falciparum and subsequent development of the oocyst phase in mosquitoes (Wiley et al, 2015). Whether IPP synthesis is essential in liver stage human malarias, and therefore of potential utility as a prophylaxis target, is moot with one group claiming an effect for fosmidomycin in P. berghei liver stages (Nair et al, 2011) and another group claiming no effect (Baumeister et al, 2011).…”

The cell biology of malaria infection of mosquito: advances and opportunities

“…Recognizing the female gametocyte provides the majority of the biomass of the zygote/ookinete, this expansion of energy provision is understandable, but the male gametocyte forms eight microgametes devoid of both plastids, suggesting in the male cell that it performs a vital function during gametocytogenesis or during the dramatic events of gamete formation in the mosquito? It has been shown that the apicoplast provides isoprenoids essential for gametocytogenesis (Wiley et al ., ), and up‐regulation of glyoxalase provides defence against oxidative stress (Okamoto et al ., ) that has recently been shown to be a component of the mosquitoes' responses to malarial infection (Shrinet et al ., ). Up‐regulation of genes encoding type II fatty acid, and 15 of 16 TCA enzymes in the mature gametocyte are also consistent with the cytological observations.…”

Metabolomics profiling reveals new aspects of dolichol biosynthesis inPlasmodium falciparum

“…Downstream de novo cis-polyisoprenoid biosynthesis of dolichols is also inactive in mature RBCs 5 but dolichols synthesized during erythropoiesis are still present in erythrocytes 6,7 . On the other hand, P. falciparum has active isoprenoid biosynthesis during the asexual intraerythrocytic developmental cycle as well as during gametocytogenesis where the isoprenoid precursors IPP and DMAPP are synthesized through the methylerythritol phosphate (MEP) pathway [8][9][10] .The MEP pathway is localized in the apicoplast 11,12 , a unique chloroplast-like organelle essential for growth and pathogenesis of the malaria parasite 13 (Fig. 1).…”

“…Then, cultures were supplemented with a mixture of [3-13 C]IPP and unlabeled IPP (1:1) at 200 µM final concentration in the presence of FOS. It is well established that 200 µM of exogenous IPP is necessary to reverse growth inhibition caused by FOS or the absence of the apicoplast 10,14,[42][43][44] . During optimization of the 13 C-biolabeling experimental design, we established that parasites required at least 20-24 h of growth in the presence of the 13 C-precursor starting at ring stage in order to observe 13 Cenrichment in polyprenols and dolichols (data not shown).…”