Dataset Information

Phosphodiesterase beta controls cAMP signalling during malaria parasite erythrocyte invasion

ABSTRACT: Cyclic nucleotide signalling is a major regulator of malaria parasite differentiation. Specific phosphodiesterase (PDE) enzymes are known to control cGMP levels in the parasite, but the mechanisms by with cAMP is regulated remain enigmatic. Here we show that P. falciparum PDEbeta translocates via the ER to an apical location and finally to the plasma membrane of merozoites within the segmented schizont. PDEbeta is essential for blood stage replication, with conditional gene disruption causing a profound invasion phenotype and rapid death of those merozoites that are able to invade a host erythrocyte. Importantly we also demonstrate that PDEbeta is able to hydrolyse both cAMP and cGMP. Loss of PDEbeta activity results in significantly elevated levels of cAMP which correlate temporally with the observed reduction in merozoite invasion. Quantitative phosphoproteomic analysis revealed a >2-fold increase in phosphorylation for >250 phosphosites following silencing of PfPDEbeta. These included a highly significant increase in phosphorylation at PKA substrate consensus sequences. Our results suggest that dysregulated phosphorylation of MyoA S19 and AMA1 S610 likely contributes to the PfPDEbeta knockout invasion phenotype, that PKG activity governs cAMP levels and PKA activation prior to merozoite egress, and that PfPDEbeta has an essential function in regulation cAMP levels in early intra-erythrocytic development in P. falciparum.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Homo Sapiens (human) Plasmodium Falciparum Mad71/papua New Guinea

SUBMITTER: Andrew Jones

LAB HEAD: Bram Snijders

PROVIDER: PXD009157 | Pride | 2019-02-27

REPOSITORIES: Pride

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Publications

Phosphodiesterase beta is the master regulator of cAMP signalling during malaria parasite invasion.

Flueck Christian C Drought Laura G LG Jones Andrew A Patel Avnish A Perrin Abigail J AJ Walker Eloise M EM Nofal Stephanie D SD Snijders Ambrosius P AP Blackman Michael J MJ Baker David A DA

PLoS biology 20190222 2

Cyclic nucleotide signalling is a major regulator of malaria parasite differentiation. Phosphodiesterase (PDE) enzymes are known to control cyclic GMP (cGMP) levels in the parasite, but the mechanisms by which cyclic AMP (cAMP) is regulated remain enigmatic. Here, we demonstrate that Plasmodium falciparum phosphodiesterase β (PDEβ) hydrolyses both cAMP and cGMP and is essential for blood stage viability. Conditional gene disruption causes a profound reduction in invasion of erythrocytes and rapi ...[more]

PMID: 30794532

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Project description:Ubiquitylation is a common post translational modification of eukaryotic proteins. Protein ubiquitylation increases in the transition from intracellular schizont to extracellular merozoite in the asexual blood stage cycle of the human malaria parasite, Plasmodium falciparum (Pf). Here, we identify specific ubiquitylation sites of protein substrates in three intracellular parasite stages and extracellular merozoites; a total of 1464 sites in 546 proteins were identified. 469 ubiquitylated proteins were identified in merozoites compared with only 160 in the preceding intracellular schizont stage, indicating a large increase in protein ubiquitylation associated with merozoite maturation. Following merozoite invasion of erythrocytes, few ubiquitylated proteins were detected in the first intracellular ring stage but as parasites matured through trophozoite to schizont stages the extent of ubiquitylation increased. We identified commonly used ubiquitylation motifs and groups of ubiquitylated proteins in specific areas of cellular function, for example merozoite pellicle proteins involved in erythrocyte invasion, exported proteins, and histones. To investigate the importance of ubiquitylation we screened ubiquitin pathway inhibitors in a parasite growth assay and identified the ubiquitin activating enzyme (UBA1 or E1) inhibitor, MLN7243 (TAK-243) to be particularly effective. This small molecule was shown to be a potent inhibitor of recombinant PfUBA1, and a structural homology model of MLN7243 bound to the parasite enzyme highlights avenues for the development of P. falciparum specific inhibitors. We constructed a genetically modified parasite with a rapamycin-inducible functional deletion of uba1; addition of either MLN7243 or rapamycin to the recombinant parasite line resulted in the same phenotype, with parasite development blocked at the schizont stage. These results indicate that the intracellular target of MLN7243 is UBA1, and this activity is essential for the final differentiation of schizonts to merozoites. The ubiquitylation of many merozoite proteins and their disappearance in ring stages are consistent with the idea that ubiquitylation leads to their destruction via the proteasome once their function is complete following invasion, which would allow amino acid recycling in the period prior to the parasite’s elaboration of a new food vacuole.

Project description:Gene expression in malaria parasites is subject to various layers of regulation, including histone post-translational modifications (PTMs). Gene regulatory mechanisms have been extensively studied during the main developmental stages of Plasmodium parasites inside erythrocytes, from the ring stage following invasion to the schizont stage leading up to egress. However, gene regulation in merozoites that mediate the transition from one host cell to the next is an understudied area of parasite biology. Here, we sought to characterize gene expression and the corresponding histone PTM landscape during this stage of the parasite lifecycle through RNA-seq and ChIP-seq on P. falciparum blood stage schizonts, merozoites, and rings, as well as P. berghei liver stage merozoites. In both hepatic and erythrocytic merozoites, we identified a subset of genes with a unique histone PTM profile characterized by depletion of H3K4me3 in their promoter regions. These genes were upregulated in merozoites and rings, had roles in protein export, translation, and host cell remodeling, and shared a DNA motif. These results indicate that similar regulatory mechanisms may underlie merozoite formation in the liver and blood stages. We also observed that H3K4me2 was deposited in gene bodies of gene families encoding variant surface antigens in erythrocytic merozoites, which may facilitate switching of gene expression between different members of these families. Finally, H3K18me and H2K27me were uncoupled from gene expression and were enriched around the centromeres in erythrocytic merozoites, suggesting roles in the maintenance of chromosomal organization during schizogony. Together, our results demonstrate that extensive changes in gene expression and histone landscape occur during the schizont-to-ring transition to facilitate productive erythrocyte infection. The dynamic remodeling of the transcriptional program in hepatic and erythrocytic merozoites makes this stage attractive as a target for novel anti-malarial approaches that may have activity against both the liver and blood stages.

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Dataset Information

Phosphodiesterase beta controls cAMP signalling during malaria parasite erythrocyte invasion

Publications

Phosphodiesterase beta is the master regulator of cAMP signalling during malaria parasite invasion.

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