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Cooperative binding of ApiAP2 transcription factors is crucial for the expression of virulence genes in Toxoplasma gondii. [ChIP-chip]

ABSTRACT: Toxoplasma gondii is a unicellular eukaryote belonging to the Apicomplexa phylum. It is an obligate intracellular parasite of critical importance to primarily infected pregnant women and immunosuppressed patient. ApiAP2 are a family of conserved transcription factors (TF) that play an important role in regulating gene expression in apicomplexan parasites. Previous studies had revealed the ability of one of these TFs, TgAP2XI-5, to bind to transcriptionally active promoters of genes expressed during the S/M phase such as rhoptry and micronemes genes. However, expression of TgAP2XI-5 is constitutive during the tachyzoite cell cycle. To better understand how its function is regulated, we identified proteins interacting with TgAP2XI-5 including a cell cycle regulated ApiAP2 TFs, TgAP2X-5. The purpose of the study is to determine the impact of the absence of TgAP2X-5 on the binding of TgAP2XI-5 on its targets. Chromatin immunoprecipitation (ChIP) of TgAP2XI-5 together with chromatin in absence of TgAP2X-5 profiling by ChIP-on-chip analysis demonstrated that TgAP2X-5 co-acts with TgAP2XI-5 for its binding to DNA of certain promoter targets.

ORGANISM(S): Toxoplasma gondii ME49 Toxoplasma gondii

PROVIDER: GSE109086 | GEO | 2018/05/30

REPOSITORIES: GEO

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Cooperative binding of ApiAP2 transcription factors is crucial for the expression of virulence genes in Toxoplasma gondii. [RNA-seq]

Project description:Toxoplasma gondii is a unicellular eukaryote belonging to the Apicomplexa phylum. It is an obligate intracellular parasite of critical importance to primarily infected pregnant women and immunosuppressed patient. ApiAP2 are a family of conserved transcription factors (TF) that play an important role in regulating gene expression in apicomplexan parasites. Previous studies had revealed the ability of one of these TFs, TgAP2XI-5, to bind to transcriptionally active promoters of genes expressed during the S/M phase such as rhoptry and micronemes genes. However, expression of TgAP2XI-5 is constitutive during the tachyzoite cell cycle. To better understand how its function is regulated, we identified proteins interacting with TgAP2XI-5 including a cell cycle regulated ApiAP2 TFs, TgAP2X-5. The purpose of the study is to determine the impact of the absence of a TF (TgAP2X-5) on the wide expression profile of a Toxoplasma gondii strain.

2018-05-30 | GSE106864 | GEO

Transcriptomic analysis of Plasmodium berghei apiAP2 KO mutants

Project description:During the progress through its complex life cycle, the malaria parasite requires strict control of gene expression but the mechanism controlling this process remain poorly understood and unexplored for therapeutic purposes. A group of the apicomplexa-specific putative transcription factors with AP2 DNA binding domain (apiAP2) has been identified as the major regulators of the parasite transcriptome at multiple stages. The targets and the role of the majority of the members of the family however are unknown.

2017-03-08 | GSE80634 | GEO

A single master regulator controls asexual cell cycle division patterns in Toxoplasma gondii [ChIP-Seq]

Project description:ApiAP2 are a family of conserved transcription factors (TF) that play an important role in regulating gene expression in apicomplexan parasites. ApiAP2 proteins that may control the cell cycle dependent expression program are to be discovered. To better understand how these cell-cycle dependent gene expression profiles are established, we identified ApiAP2 proteins showing a cell cycle dependent expression. Using the Auxin-degradation system, we produced several inducible knock-down (iKD) mutant for these ApiAP2 proteins. Among them, a cell-cycle regulated ApiAP2 is expressed during the late S-phase of the tachyzoite cell-cycle. The iKD mutant parasites for this gene are unable to proliferate. In presence of Auxin, the mutant parasites do not produce daughter cells and are arrested in the early phase of budding. This indicates that this TF may specifically regulate the early steps of the daughter cell formation. Using RNA-Seq, we demonstrate that the level of expression of number of transcripts is affected by the knock-down of this potential TF.

2020-10-29 | GSE150405 | GEO

A single master regulator controls asexual cell cycle division patterns in Toxoplasma gondii [RNA-Seq]

2020-10-29 | GSE150334 | GEO

A knockout screen of ApiAP2 genes reveals networks of interacting transcriptional regulators controlling the Plasmodium life cycle.

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.

2017-02-08 | PXD005180 | Pride

PfAP2-HC, an unusual, heterochromatin-associated ApiAP2 factor of Plasmodium falciparum

Project description:In this study we have investigated PfAP2-HC (PF3D7_1456000), a protein that was identified by co-immunoprecipitation with PfHP1 coupled with liquid chromatography-tandem mass spectrometry. PfAP2-HC belongs to the ApiAP2 family, the main transcription factor family in Apicomplexan parasites. We have confirmed that AP2-HC colocalises with HP1 with the use of immunofluorescence assays and chromatin immunoprecipitation-sequencing. We show that PfAP2-HC is not required for heterochromatin maintenance and inheritance with the use of PfAP2-HC Kock out and knockdown. We show with transcriptome-wide microarray time course analysis that PfAP2-HC does not act as a transcription factor in blood stage parasites. We demonstrate that the AP2 domain is dispensable for heterochromatin targeting by introducing a premature stop codon before the AP2 domain. We show that PfAP2-HC binding to heterochromatin dependents on PfHP1. and PfAP2-HC is likely not involved in de novo heterochromatin formation

2020-11-04 | GSE154840 | GEO

Identification of RON13 binding with with RON4 substrate

Project description:Active host cell invasion by the obligate intracellular apicomplexan parasites relies on the formation of a moving junction (MJ), which joins parasite and host cell plasma membranes during entry. Invading Toxoplasma gondii tachyzoites secrete a complex of RON proteins from the rhoptry organelles that provide the components of the MJ on the cytoplasmic side of the host cell membrane. This study highlights the role of a rhoptry resident kinase, RON13, that plays a crucial role during host cell entry and is a virulence factor in the mouse model of infection. Comparative phosphoproteomics demonstrated RON13-dependent phosphorylation of secreted rhoptry proteins and primarily the RONs complex. Structural and biochemical analysis of RON13 revealed the atypical nature of this active secretory pathway kinase, unique to the Apicomplexa.

2021-05-10 | PXD023791 | Pride

Identification of novel rhoptry secretion factors in Toxoplasma gondii _ ND12

Project description:Apicomplexan parasites, together with ciliates and dinoflagellates, belong to the Alveolata superphylum. Apicomplexa possess secretory organelles called rhoptries that undergo regulated exocytosis during invasion. Upon injection into the host cell, rhoptry proteins support invasion, vacuole formation, and subversion of host immune function. Rhoptry exocytosis involves a “rosette” of 8 particles embedded in the plasma membrane; such peculiar structure is also conserved in Ciliata and its formation requires Alveolata-restricted “Nd” proteins. These findings point to the existence of an Alveolata-conserved mechanism for the discharge of secretory organelles, and provide proof of concept that we can decipher rhoptry exocytosis machinery using a PAN-Alveolata approach. Thus, to uncover new rhoptry secretion factors, we used the transcriptional profiles of Nd genes of the ciliate Tetrahymena thermophila to select genes that are co-regulated, and also conserved in Apicomplexa. In this way we identified two uncharacterized Tetrahymena proteins that contribute to the exocytosis of secretory organelles. They have similar architecture and show homology with Plasmodium Cysteine Repeat Modular Proteins (CRMPs), a family of proteins essential for Plasmodium transmission from the mosquito to the host. We functionally characterized the two Toxoplasma CRMPs, including their dynamic location during invasion. They are not required for rosette formation, but they are essential for rhoptry secretion, suggesting a function distinct from that of previously characterized exocytic “Nd” factors. To characterize interacting proteins we performed pull-down experiments and analyzed the eluates by liquid chromatography-tandem mass spectrometry.

2022-10-20 | PXD031164 | Pride

Identification of novel rhoptry secretion factors in Toxoplasma gondii _ ND11

2022-10-20 | PXD031161 | Pride

An apicomplexan bromodomain protein, TgBDP1 associates with diverse epigenetic factors to regulate essential transcriptional processes in Toxoplasma gondii

Project description:The protozoan pathogen Toxoplasma gondii relies on tight regulation of gene expression to invade and establish infection in its host. The divergent gene regulatory mechanisms of Toxoplasma and related apicomplexan pathogens rely heavily on regulators of chromatin structure and histone modifications. The important contribution of histone acetylation for Toxoplasma in both acute and chronic infection has been demonstrated, where histone acetylation increases at active gene loci. However, the direct consequences of specific histone acetylation marks and the chromatin pathway that influences transcriptional regulation in response to the modification is unclear. As a reader of lysine acetylation, the bromodomain serves as a mediator between the acetylated histone and transcriptional regulators. Here we show that the bromodomain protein TgBDP1 which is conserved amongst Apicomplexa and within the Alveolata superphylum, is essential for Toxoplasma asexual proliferation. Using CUT&TAG we demonstrate that TgBDP1 is recruited to transcriptional start sites of a large proportion of parasite genes. Transcriptional profiling during TgBDP1 knockdown revealed that loss of TgBDP1 leads to major dysregulation of gene expression, implying multiple roles for TgBDP1 in both gene activation and repression. This is supported by interactome analysis of TgBDP1 demonstrating that TgBDP1 forms a core complex with two other bromodomain proteins and an ApiAP2 factor. This core complex appears to interact with other epigenetic factors such as nucleosome remodelling complexes. We conclude that TgBDP1 interacts with diverse epigenetic regulators to exert opposing influences on gene expression in the Toxoplasma tachyzoite.

2023-05-31 | GSE228853 | GEO

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