Project description:In the malaria parasite Plasmodium falciparum, the switch from asexual multiplication to sexual differentiation into gametocytes is essential for transmission to mosquitos. One of the key determinants of sexual commitment is the transcription factor PfAP2-G, which has been proposed to orchestrate this crucial cell fate decision by driving expression of gametocyte genes. We show conclusively that PfAP2-G is a transcriptional activator of gametocyte genes and identify the earliest known markers expressed during commitment. Remarkably, we also find that in sexually committed cells, PfAP2-G is associated with the promoters of genes important for red blood cell invasion and activates them through its interactions with a second transcription factor. We thus demonstrate an intriguing transcriptional link between the apparently opposing processes of red blood cell invasion and gametocytogenesis that is coordinated by the master regulator PfAP2-G. This finding has important implications for the development of new anti-malarial drugs that block the invasion of red blood cells by sexually committed cells, thereby preventing parasite transmission.
Project description:Obligate intracellular parasites must efficiently invade host cells in order to mature and be transmitted. For the malaria parasite Plasmodium falciparum, invasion of host red blood cells (RBCs) is essential. Here we describe a parasite-specific transcription factor belonging to the Apicomplexan Apetala 2 (ApiAP2) family that is responsible for regulating the expression of a subset of merozoite genes involved in RBC invasion (PfAP2-I). Our genome-wide analysis by ChIP-seq shows that PfAP2-I interacts with a specific DNA motif in the promoters of these genes. msp5 transcription levels decrease when the PfAP2-I DNA-binding motif is mutated in PfAP2-I-GFP parasites, showing that PfAP2-I must bind the DNA motif in order for msp5 to be transcribed.
Project description:Obligate intracellular parasites must efficiently invade host cells in order to mature and be transmitted. For the malaria parasite Plasmodium falciparum, invasion of host red blood cells (RBCs) is essential. Here we describe a parasite-specific transcription factor belonging to the Apicomplexan Apetala 2 (ApiAP2) family that is responsible for regulating the expression of a subset of merozoite genes involved in RBC invasion (PfAP2-I). Our genome-wide analysis by ChIP-seq shows that PfAP2-I interacts with a specific DNA motif in the promoters of these genes. msp5 transcription levels decrease when the PfAP2-I DNA-binding motif is mutated in PfAP2-I-GFP parasites, showing that PfAP2-I must bind the DNA motif in order for msp5 to be transcribed.
Project description:Transcriptional profiling of transgenic P. falciparum asexual blood stage parasites of the transgenic strain 3D7/DDGFP-PfAP2-HC at five time points during intra-erythrocytic parasite development. The DD (FKBP destabilisation domain) allows for the conditional expression of fusion proteins: DD fusion proteins are rapidly degraded or stably expressed in absence or presence of the stabilising ligand Shield-1, respectively (Banaszynski LA, Chen LC, Maynard-Smith LA, Ooi AG, Wandless TJ. A rapid, reversible, and tunable method to regulate protein function in living cells using synthetic small molecules.Cell. 2006 Sep 8;126(5):995-1004). The goal of this experiment was to identify genes differentially expressed in DDGFP-PfAP2-HC-expressing compared to DDGFP-PfAP2-HC-depleted parasites during the intra-erythtrocytic cell cycle.
Project description:In the malaria parasite Plasmodium falciparum, the switch from asexual multiplication to sexual differentiation into gametocytes is essential for transmission to mosquitos. One of the key determinants of sexual commitment is the transcription factor PfAP2-G, which has been proposed to orchestrate this crucial cell fate decision by driving expression of gametocyte genes. We show conclusively that PfAP2-G is a transcriptional activator of gametocyte genes and identify the earliest known markers expressed during commitment. Remarkably, we also find that in sexually committed cells, PfAP2-G is associated with the promoters of genes important for red blood cell invasion and activates them through its interactions with a second transcription factor. We thus demonstrate an intriguing transcriptional link between the apparently opposing processes of red blood cell invasion and gametocytogenesis that is coordinated by the master regulator PfAP2-G. This finding has important implications for the development of new anti-malarial drugs that block the invasion of red blood cells by sexually committed cells, thereby preventing parasite transmission.
Project description:Differentiation from asexual blood stages to sexual gametocytes is required for transmission of malaria parasites from the human to the mosquito host. Preventing gametocyte commitment and development would block parasite transmission, but the underlying molecular mechanisms behind these processes remain poorly understood. Here, we report that the ApiAP2 transcription factor, PfAP2-G2 (PF3D7_1408200) plays a critical role in the maturation of Plasmodium falciparum gametocytes. PfAP2-G2 binds to the promoters of a wide array of genes that are expressed at many stages of the parasite life cycle. Interestingly, we also find binding of PfAP2-G2 within the gene body of almost 3000 genes, which strongly correlates with the location of H3K36me3 and several other histone modifications as well as Heterochromatin Protein 1 (HP1), suggesting that occupancy of PfAP2-G2 in gene bodies may serve as an alternative regulatory mechanism. Disruption of pfap2-g2 does not impact asexual development, parasite multiplication rate, or commitment to sexual development but the majority of sexual parasites are unable to mature beyond stage III gametocytes. The absence of pfap2-g2 leads to overexpression of 28% of the genes bound by PfAP2-G2 and none of the PfAP2-g2 bound are downregulated, suggesting that it is a repressor. We also find that PfAP2-G2 interacts with chromatin remodeling proteins, a microrchidia (MORC) protein, and another ApiAP2 protein (PF3D7_1139300). Overall our data demonstrate that PfAP2-G2 is an important transcription factor that establishes an essential gametocyte maturation program in association with other chromatin-related proteins.