The NTP Generating Activity of Pyruvate Kinase II is Critical for Apicoplast Maintenance in Plasmodium falciparum
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ABSTRACT:
PROVIDER: PRJNA563082 | ENA |
REPOSITORIES: ENA
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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. Keywords: Plasmodium falciparum treated with Doxycycline
2006-07-11 | GSE5267 | 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: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 found that pyruvate kinase II (PyrKII) is essential for organelle maintenance, but that production of pyruvate by PyrKII is not responsible for this phenomenon. Enzymatic characterization of PyrKII revealed activity against all NDPs and dNDPs tested, suggesting that it may be capable of generating a broad range of nucleotide triphosphates. Conditional mislocalization of PyrKII resulted in decreased 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.
| S-EPMC7556864 | biostudies-literature
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: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:In the malaria parasite Plasmodium falciparum, the expression of many genes is regulated by heterochromatin (HC) based on the histone mark tri-methylation of histone H3 lysine 9 (H3K9me3). HC assembly involves three distinct steps: de novo nucleation, spreading and maintenance. Nucleation, which consists in formation of HC in a previously euchromatic region, determines at which specific regions of the genome HC occurs, but this process is not well understood in malaria parasites. Here we investigated the DNA sequence cis determinants of HC nucleation in P. falciparum, using a screening approach based on integration of fragments from different heterochromatic genes into an euchromatic locus, followed by chromatin immunoprecipitation (ChIP). We found that fragments of var gene upstream regions nucleated HC efficiently, whereas fragments from the pfap2-g upstream region or from the mspdbl2 locus did not nucleate HC. Fragments from the beginning of the coding sequence (CDS) of pfap2-g nucleated HC with low efficiency, as evidenced by nucleation requiring long fragments of ~2 kb and occurring only in a fraction of the parasites. These results demonstrate that the primary DNA sequence is a main determinant of HC nucleation in P. falciparum. We also studied HC maintenance at the pfap2-g locus, which demonstrated that specific parts of the upstream region, different from the regions competent for HC nucleation, are required for maintenance. Together, our results provide initial insight into how HC is directed to specific loci and maintained in P. falciparum.
2025-04-07 | GSE287562 | GEO
Project description:Tetracyclines Specifically Target the Apicoplast of the Malaria Parasite Plasmodium falciparum
| PRJNA96375 | ENA
Project description:Heterochromatin de novo formation and maintenance in Plasmodium falciparum
| PRJNA1213753 | ENA
Project description:Blood-stage Plasmodium falciparum parasites rely on a non-photosynthetic plastid, the apicoplast, for survival, making it an attractive target for antimalarial intervention. Like the mitochondrion, the apicoplast cannot be generated de novo and must be inherited by daughter parasites during cell division. This process relies on coordinated fission events, yet the molecular mechanisms remain poorly understood. Here, we identify a previously uncharacterized P. falciparum protein (Pf3D7_0613600), which we name PfAnchor, as a key regulator of apicoplast fission. Using Ultrastructure Expansion Microscopy (U-ExM), we show that PfAnchor localizes to the apicoplast throughout the asexual life cycle. Conditional depletion disrupts apicoplast fission, leading to incomplete cytokinesis and parasite death. Notably, loss of apicoplast branching via azithromycin treatment rescues these defects, underscoring Anchor’s specific role in apicoplast division. Immunoprecipitation further identifies an interaction with the dynamin-like GTPase PfDyn2, a key mediator of both apicoplast and mitochondrial fission, establishing PfAnchor as the first apicoplast-specific dynamin adaptor protein. Our findings define PfAnchor as an essential factor for apicoplast fission and inheritance in P. falciparum blood-stage parasites, highlighting parasite-specific organelle division as a potential vulnerability for therapeutic intervention.
2025-10-27 | PXD062126 | Pride