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Phosphodiesterase beta is the master regulator of cAMP signalling during malaria parasite invasion
Christian Flueck1, Laura G Drought1, Andrew Jones2
1Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom.
Abstract:
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 rapid death of those merozoites that invade. We show that this dual phenotype results from elevated cAMP levels and hyperactivation of the cAMP-dependent protein kinase (PKA). Phosphoproteomic analysis of PDEβ-null parasites reveals a >2-fold increase in phosphorylation at over 200 phosphosites, more than half of which conform to a PKA substrate consensus sequence. We conclude that PDEβ plays a critical role in governing correct temporal activation of PKA required for erythrocyte invasion, whilst suppressing untimely PKA activation during early intra-erythrocytic development.
Insights
Plasmodium falciparum phosphodiesterase β (PDEβ) hydrolyzes both cAMP and cGMP, proving essential for malaria parasite survival. Its absence disrupts erythrocyte invasion due to elevated cAMP and PKA hyperactivation.
Area of Science:
- Malariology
- Molecular Parasitology
- Cellular Signalling
Background:
- Cyclic nucleotide signalling regulates malaria parasite differentiation.
- Phosphodiesterases (PDEs) control cyclic GMP (cGMP) but cAMP regulation is unclear.
Purpose of the Study:
- Investigate the role of Plasmodium falciparum phosphodiesterase β (PDEβ) in cyclic nucleotide regulation.
- Determine PDEβ's function in blood-stage malaria parasite viability and erythrocyte invasion.
Main Methods:
- Conditional gene disruption of PDEβ in Plasmodium falciparum.
- Analysis of parasite invasion efficiency and viability.
- Phosphoproteomic analysis to identify PKA substrates.
Main Results:
- PDEβ hydrolyzes both cAMP and cGMP and is essential for blood-stage viability.
- PDEβ disruption leads to reduced erythrocyte invasion and merozoite death.
- Elevated cAMP levels and PKA hyperactivation were observed in PDEβ-null parasites.
- Over 200 phosphosites showed increased phosphorylation, with many matching PKA substrate motifs.
Conclusions:
- PDEβ is critical for regulating PKA activation timing during erythrocyte invasion.
- PDEβ suppresses premature PKA activation in early intra-erythrocytic stages.
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