A mevalonate bypass system facilitates elucidation of apicoplast biology in malaria parasites
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ABSTRACT:
ORGANISM(S): Plasmodium falciparum
PROVIDER: GSE136169 | GEO | 2020/02/11
REPOSITORIES: GEO
Similar Datasets
Project description:The apicoplast of Plasmodium falciparum parasites is believed to rely on the import of three-carbon phosphate compounds for use in organelle anabolic pathways, in addition to the generation of energy and reducing power within the organelle. We generated a series of genetic deletions in an apicoplast metabolic bypass line to determine which genes involved in apicoplast carbon metabolism are required for blood-stage parasite survival and organelle maintenance. We were able to demonstrate that pyruvate kinase II (PyrKII), the sole predicted source of pyruvate and NTPs within the apicoplast, is essential for organelle maintenance. However, deletions within apicoplast pathways that metabolize pyruvate did not result in organelle disruption, indicating that NTPs generated by PyrKII are the products required for this process. Enzymatic characterization of PyrKII revealed that it was active against all NDPs and dNDPs tested with broad substrate specificity, suggesting that it may be capable of generating any and all NTPs and dNTPs within the organelle. Conditional mislocalization of PyrKII resulted in a decrease in transcript levels within the apicoplast that preceded organelle disruption, suggesting that PyrKII is required for organelle maintenance due to its role in nucleotide triphosphate generation within the apicoplast.
2020-07-31 | GSE136688 | GEO
Project description:Tetracyclines are effective but slow-acting antimalarial drugs whose mechanism of action remains uncertain. To characterize the antimalarial mechanism of tetracyclines, we evaluated their stage-specific activities, impacts on parasite transcription, and effects on two predicted organelle targets, the apicoplast and the mitochondrion, in cultured Plasmodium falciparum. Antimalarial effects were much greater after two 48-h life cycles than after one cycle, even if the drugs were removed at the end of the first cycle. Doxycycline-treated parasites appeared morphologically normal until late in the second cycle of treatment but failed to develop into merozoites. Doxycycline specifically impaired the expression of apicoplast genes. Apicoplast morphology initially appeared normal in the presence of doxycycline. However, apicoplasts were abnormal in the progeny of doxycycline-treated parasites, as evidenced by a block in apicoplast genome replication, a lack of processing of an apicoplast-targeted protein, and failure to elongate and segregate during schizogeny. Replication of the nuclear and mitochondrial genomes and mitochondrial morphology appeared normal. Our results demonstrate that tetracyclines specifically block expression of the apicoplast genome, resulting in the distribution of nonfunctional apicoplasts into daughter merozoites. The loss of apicoplast function in the progeny of treated parasites leads to a slow but potent antimalarial effect. We analyzed a series of 12 microarrays covering 55 hours of Plasmodium falciparum treated with doxycycline and 12 microarrays covering the same 55 hours with no doxycycline treatment
2010-07-01 | E-GEOD-5267 | biostudies-arrayexpress
Project description:A mevalonate bypass system facilitates elucidation of apicoplast biology in malaria parasites
| PRJNA561421 | ENA
Project description:Tetracyclines are effective but slow-acting antimalarial drugs whose mechanism of action remains uncertain. To characterize the antimalarial mechanism of tetracyclines, we evaluated their stage-specific activities, impacts on parasite transcription, and effects on two predicted organelle targets, the apicoplast and the mitochondrion, in cultured Plasmodium falciparum. Antimalarial effects were much greater after two 48-h life cycles than after one cycle, even if the drugs were removed at the end of the first cycle. Doxycycline-treated parasites appeared morphologically normal until late in the second cycle of treatment but failed to develop into merozoites. Doxycycline specifically impaired the expression of apicoplast genes. Apicoplast morphology initially appeared normal in the presence of doxycycline. However, apicoplasts were abnormal in the progeny of doxycycline-treated parasites, as evidenced by a block in apicoplast genome replication, a lack of processing of an apicoplast-targeted protein, and failure to elongate and segregate during schizogeny. Replication of the nuclear and mitochondrial genomes and mitochondrial morphology appeared normal. Our results demonstrate that tetracyclines specifically block expression of the apicoplast genome, resulting in the distribution of nonfunctional apicoplasts into daughter merozoites. The loss of apicoplast function in the progeny of treated parasites leads to a slow but potent antimalarial effect. Keywords: Plasmodium falciparum treated with Doxycycline
2006-07-11 | GSE5267 | GEO
Project description:The malaria parasite Plasmodium falciparum contains the apicoplast organelle that synthesize isoprenoids, which are metabolites necessary for post-translational modification of Plasmodium proteins. We used fosmidomycin, an antibiotic that inhibits isoprenoid biosynthesis, to identify mechanisms that underlie the development of the parasite’s adaptation to the drug at sub-lethal concentrations. We first determined a concentration of fosmidomycin that reduced parasite growth by ~50% over one intraerythrocytic developmental cycle (IDC). At this dose, we maintained synchronous parasite cultures for one full IDC, and collected metabolomic and transcriptomic data at multiple time points to capture global and stage-specific alterations. We integrated the data with a genome-scale metabolic model of P. falciparum to characterize the metabolic adaptations of the parasite in response to fosmidomycin treatment. Our simulations showed that, in treated parasites, the synthesis of purine-based nucleotides increased, whereas the synthesis of phosphatidylcholine during the trophozoite and schizont stages decreased. Specifically, the increased polyamine synthesis led to increased nucleotide synthesis, while the reduced methyl-group cycling led to reduced phospholipid synthesis and methyltransferase activities. These results indicate that fosmidomycin-treated parasites compensate for the loss of prenylation modifications by directly altering processes that affect nucleotide synthesis and ribosomal biogenesis to control the rate of RNA translation during the IDC. This also suggests that combination therapies with antibiotics that target the compensatory response of the parasite, such as nucleotide synthesis or ribosomal biogenesis, may be more effective than treating the parasite with fosmidomycin alone.
2021-01-27 | GSE159516 | GEO
Project description:Abstract: The antimalarial activity of the antibiotic thiostrepton has long been attributed to inhibition of apicoplast protein synthesis through binding of apicoplast ribosomal RNA. However, the kinetics of parasite death upon thiostrepton treatment differ from those seen for other inhibitors of apicoplast housekeeping functions. We have analysed global changes in gene expression of the malaria parasite, Plasmodium falciparum, in an attempt to shed light on the responses of the parasite to this drug. Our results indicate a delay in gene expression profiles of thiostrepton-treated parasites. A small number of genes appear to be regulated outside of this trend; our data suggest a response from genes encoding components of the mitochondrial translational machinery, while little response is seen from genes encoding apicoplast-targeted proteins. Our findings are consistent with an effect of thiostrepton on mitochondrial protein synthesis, and thus warrant a re-evaluation of the target of thiostrepton in Plasmodium. They also provide some suggestion of mitochondrion – nucleus signalling in the parasite. 3 biological replicates each for treated and untreated: control (1/2000 DMSO) and LD70 thiostrepton, respectively
2011-06-30 | E-GEOD-28701 | biostudies-arrayexpress
Project description:Abstract: The antimalarial activity of the antibiotic thiostrepton has long been attributed to inhibition of apicoplast protein synthesis through binding of apicoplast ribosomal RNA. However, the kinetics of parasite death upon thiostrepton treatment differ from those seen for other inhibitors of apicoplast housekeeping functions. We have analysed global changes in gene expression of the malaria parasite, Plasmodium falciparum, in an attempt to shed light on the responses of the parasite to this drug. Our results indicate a delay in gene expression profiles of thiostrepton-treated parasites. A small number of genes appear to be regulated outside of this trend; our data suggest a response from genes encoding components of the mitochondrial translational machinery, while little response is seen from genes encoding apicoplast-targeted proteins. Our findings are consistent with an effect of thiostrepton on mitochondrial protein synthesis, and thus warrant a re-evaluation of the target of thiostrepton in Plasmodium. They also provide some suggestion of mitochondrion – nucleus signalling in the parasite.
2011-06-30 | GSE28701 | GEO
Project description:New antimalarial drugs are urgently needed to control drug resistant forms of the malaria parasite, Plasmodium falciparum. Although mitochondrial metabolism is the target of both existing drugs and new lead compounds, the role of the mitochondrial tricarboxylic acid (TCA) cycle remains poorly understood. Herein, we describe 11 genetic knockout parasite lines that delete six of the eight TCA cycle enzymes. Although all TCA knockouts grew normally in asexual blood stages, these metabolic deficiencies halted lifecycle progression in later stages. Specifically, aconitase knockout parasites arrested as late gametocytes, whereas α-ketoglutarate dehydrogenase deficient parasites failed to develop oocysts in the mosquitoes. Mass-spectrometry analysis of 13C isotope-labeled TCA mutant parasites showed that P. falciparum has significant flexibility in TCA metabolism. This flexibility manifested itself through changes in pathway fluxes and through altered exchange of substrates between cytosolic and mitochondrial pools. Our findings suggest that mitochondrial metabolic plasticity is essential for parasite development . Two parallel timecourses resulting in a total of 16 samples (8 wildtype, Isocitrate Dehydrogenase/alpha-Ketogluterate Dehydrogenase double knockout) were hybridized against a Cy3-labeled reference pool of 3D7 mixed stage parasites on a two-color array.
2014-08-01 | E-GEOD-59015 | biostudies-arrayexpress
Project description:Plasmodium falciparum is the etiological agent of human malaria, one of the most widespread diseases in tropical and subtropical world regions. One of the biggest problems in controlling the disease is the emergence of drug resistance, which leads to the need to discover new antimalarial compounds. One of the most promissory drugs purposed is fosmidomycin, an inhibitor of the biosynthesis of isoprene units by the methylerythritol 4-phosphate (MEP) pathway which in some cases failed in clinic studies. Once formed, isoprene units are condensed to form longer structures such as farnesyl and geranylgeranyl pyrophosphate (GGPP), which are necessary for heme O and A formation, ubiquinone, and dolichyl phosphate biosynthesis as well as for protein isoprenylation. Even though the natural substrates of polyprenyl transferases and syntheses are polyprenyl pyrophosphates, it was already demonstrated that isoprenoid alcohols (polyprenols) such as farnesol (FOH) and geranylgeraniol (GGOH) can rescue parasites from fosmidomycin. This study better investigated how this rescue phenomenon occurs by performing drug-rescue assays. By this, it was observed that phytol (POH), a 20-carbon plant isoprenoid, rescues parasites from the fosmidomycin effect, similarly to FOH or GGOH. Contrarily, neither dolichols nor nonaprenol rescue parasites from fosmidomycin. Considering this, here we characterized the transport of FOH, GGOH, and POH. Once incorporated, it was observed that these substances are phosphorylated, condensed into longer isoprenoid alcohols, and incorporated into proteins and dolichyl phosphates. Through proteomic and radiolabelling approaches, it was found that prenylated proteins are naturally attached to several isoprenoids including GGOH, dolichol, and POH if exogenously added. Furthermore, results suggest the presence of at least two promiscuous protein prenyltransferases in the parasite: one enzyme which can use FPP among other unidentified substrates and another enzyme that can use GGOH, POH, and dolichols among other substrates not identified here. Thus, was obtained further evidence for dolichols and other isoprenoid products attached to proteins. This study helps better understand apicoplast-targeting antimalarials mechanism of action as well as novel posttranslational modifications of proteins.
2022-11-28 | PXD036092 | Pride
Project description:Resistance to front-line antimalarials (artemisinin combination therapies) is spreading, and development of new drug treatment strategies to rapidly kill Plasmodium parasites that cause malaria are urgently needed. Here, we show that azithromycin—a clinically used macrolide antibiotic that targets the bacterium-like ribosome of the malaria parasites apicoplast organelle and causes a slow-killing ‘delayed death’ phenotype—can also rapidly kill parasites throughout the asexual blood-stages of the lifecycle via a ‘quick-killing’ mechanism of action. Investigation of 84 azithromycin analogues revealed nanomolar quick-killing potency that is directed against the very earliest stage of parasite development within red blood cells. Indeed, the best analogue exhibited 1600-fold higher potency than azithromycin for in vitro treatment windows less than 48 hours. Analogues were also effective against the zoonotic malaria parasite P. knowlesi, and against both multi-drug and artemisinin resistant P. falciparum lines. Metabolomic profiles of azithromycin analogue treated parasites were similar to those of chloroquine treated parasites, suggesting that the quick-killing mechanism of action may in part be localised to the parasite food vacuole. However, metabolomic signatures associated with mitochondrial disruption were also present. In addition, unlike chloroquine, azithromycin and analogues were active across blood stage development, including merozoite invasion, suggesting that these macrolides have a multi-factorial mechanism of quick-killing activity. The positioning of functional groups added to azithromycin and its quick-killing analogues altered their activity against bacterial-like ribosomes but had minimal change on quick-killing activity, which suggests that apicoplast-targeting, delayed-death activity can either be preserved or removed independently of quick-killing. Apicoplast minus parasites remained susceptible to both azithromycin and its analogues, further demonstrating that quick-killing is independent of apicoplast-targeting, delayed-death activity. Therefore, development of azithromycin and analogues as antimalarials offers the possibility of targeting parasites through both a quick-killing and delayed death mechanism of action in a single, multifactorial chemotype.
2020-02-06 | ST001315 | MetabolomicsWorkbench