Project description:Malaria parasites rely on a plastid organelle for survival during the blood stages of infection. However, the entire organelle is dispensable as long as the isoprenoid precursor isopentenyl pyrophosphate (IPP) is supplemented in the culture medium. We engineered parasites to produce isoprenoid precursors from a mevalonate-dependent pathway, creating a parasite line that replicates normally after the loss of the apicoplast organelle. We show that carbon-labeled mevalonate is specifically incorporated into isoprenoid products, opening new avenues for researching this essential class of metabolites in malaria parasites. We also show that essential apicoplast proteins, such as the enzyme target of the drug fosmidomycin, can be deleted in this mevalonate bypass parasite line, providing a method to determine the roles of other important apicoplast-resident proteins. Several antibacterial drugs kill malaria parasites because they target basic processes, such as transcription, in the organelle. We used metabolomic and transcriptomic methods to characterize parasite metabolism after azithromycin treatment triggered loss of the apicoplast. These results provide insight into the effects of apicoplast-disrupting drugs, several of which have been used to treat malaria infections in humans. Overall, the mevalonate bypass system provides a way to probe essential aspects of apicoplast biology and study the effects of drugs that target apicoplast processes.
2020-02-11 | GSE136169 | GEO
Project description:CaaX-like protease of cyanobacterial origin is required for complex plastid biogenesis in malaria parasites
Project description:Chloroplast biogenesis represents a crucial step in seedling development, and is essential for the transition to autotrophic growth in plants. This light-controlled process relies on the transcription of nuclear and plastid genomes that drives the effective assembly and regulation of the photosynthetic machinery. Here we reveal a novel regulation level for this process by showing the involvement of chromatin remodelling in the coordination of nuclear and plastid gene expression for proper chloroplast biogenesis and function. The two Arabidopsis homologs of the yeast EPL1 proteins, core components of the NuA4 histone acetyl-transferase complex, are essential for the correct assembly and performance of chloroplasts. EPL1 proteins are necessary for the coordinated expression of nuclear genes encoding most of the components of chloroplast transcriptional machinery, specifically promoting H4K5Ac deposition in these loci. These data unveil a key participation of epigenetic regulatory mechanisms in the coordinated expression of the nuclear and plastid genomes.
Project description:AP2-G is a transcription factor (TF) that is essential for gametocytogenesis of malaria parasites; however, the mechanisms for its inducing the cell linage for sexual reproduction remain unclear. In this paper, this problem is addressed by investigating its expression profile and by determining target genes genome-wide in Plasmodium berghei.
Project description:AP2-G is a transcription factor (TF) that is essential for gametocytogenesis of malaria parasites; however, the mechanisms for its inducing the cell linage for sexual reproduction remain unclear. In this paper, this problem is addressed by investigating its expression profile and by determining target genes genome-wide in Plasmodium berghei.
Project description:Plastids emit signals that broadly affect cellular processes. Based on previous genetic analyses, we propose that plastid signaling regulates the downstream components of a light signaling network and that these interactions coordinate chloroplast biogenesis with both the light environment and development by regulating gene expression. We tested these ideas by analyzing light-regulated and plastid-regulated transcriptomes. We found that the plastid is a major regulator of light signaling, attenuating the expression of more than half of all light-regulated genes in our dataset and changing the nature of light regulation for a smaller fraction of these light-regulated genes. Our analyses provide evidence that light and plastid signaling are interactive processes and are consistent with these interactions serving as major drivers of chloroplast biogenesis and function.
Project description:Gametocytes are nonreplicative sexual forms that mediate malaria transmission to a mosquito vector. They are generated from asexual blood stage parasites, which proliferate in the circulation. However, it remains largely unknown as to how this transition is genetically regulated. Here, we report that an Apetala2 (AP2) family transcription factor, AP2-G2, regulates the transition as a transcriptional repressor. Disruption of AP2-G2 in the rodent malaria parasites, Plasmodium berghei, did not prevent commitment to the sexual stage but halted their development before manifesting sex-specific morphologies. ChIP-seq analysis revealed that AP2-G2 targets approximately 1,500 genes and recognizes a five-base motif on their promoters. Most of these target genes are required for asexual proliferation in the blood by the parasites, thereby suggesting that AP2-G2 blocks the program for asexual replication of parasites in the blood. DNA microarray analysis showed that the identified targets constituted approximately 70% of the upregulated genes in AP2-G2-depleted parasites, and a promoter assay using a centromere plasmid demonstrated that the binding motif functions as a cis-acting negative regulatory element. These results suggest that global transcriptional repression, which occurs during the initial phase of gametocytogenesis, is an essential step to promote conversion to the sexual stage.
Project description:AP2-G is a transcription factor (TF) that is essential for gametocytogenesis of malaria parasites; however, the mechanisms for its inducing the cell linage for sexual reproduction remain unclear. In this paper, this problem is addressed by investigating its expression profile and by determining target genes genome-wide in Plasmodium berghei.
Project description:The family of apicomplexa-specific proteins with DNA binding AP2 domains (ApiAP2s) includes sequence-specific transcription factors that are key regulators of development in malaria parasites. However, functions for the majority of ApiAP2 genes remain unknown. Here, a systematic knockout screen in Plasmodium berghei identifies ten ApiAP2 genes essential for mosquito transmission, of which four are critical for the formation of infectious ookinetes and three for sporogony. We describe unexpected non-essential functions for AP2-O and AP2-SP proteins in blood stages and identify AP2-G2 as a universal repressor active in both, asexual and sexual stages. Comparative transcriptomics across mutants and developmental stages reveals clusters of co-regulated genes with shared cis elements in their promoters, whose expression can be controlled positively or negatively by different ApiAP2 gene deletions. We propose that stage-specific interactions between ApiAP2 proteins on partly overlapping sets of target genes generate the complex transcriptional network that controls the Plasmodium life cycle.