Affinage · Plasmodium

CDPK5

PF3D7_1337800 · calcium-dependent protein kinase 5

Annotated
2026-09-08
7 papers in source corpus 5 papers cited in narrative 5 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

CDPK5 (PF3D7_1337800) is a calcium-dependent protein kinase that drives egress of Plasmodium from its host cell by triggering microneme discharge, acting downstream of and in cooperation with cGMP-dependent protein kinase (PKG) (PMID:20466936, PMID:29487234). In P. falciparum, CDPK5 is expressed in invasive merozoites and is essential for erythrocyte egress: conditional knockdown arrests parasites as mature schizonts with intact membranes, even though egress proteases and invasion ligands mature normally, and merozoites physically freed from stalled schizonts remain invasion-competent, functionally separating egress from invasion (PMID:20466936). Mechanistically, CDPK5 colocalizes with micronemes in schizonts and its loss blocks microneme discharge; hyperactivation of PfPKG bypasses the CDPK5-dependent arrest and restores microneme release, placing CDPK5 within the PKG-coordinated protease cascade that executes egress (PMID:29487234). Phosphoproteomics of CDPK5-deficient schizonts identified 58 reduced phosphosites on 50 proteins enriched for transmembrane and transport functions, including the plasma-membrane transporter PfNPT1 as a candidate substrate (PMID:31915223). In P. berghei, CDPK5 additionally supports sporozoite motility, hepatocyte invasion, and merosome formation/release, with elevated cGMP compensating for its loss during sporozoite invasion (PMID:32866196). CDPK5 mutations, together with PfATP4 mutations, confer full resistance to pyrazoleamide antimalarials, implicating it in the targeted pathway (PMID:25422853).

Mechanistic history

Synthesis pass · year-by-year structured walk · 5 steps
  1. 2010 High

    Establishing whether CDPK5 has an essential and stage-specific role addressed whether the kinase controls a discrete step of the blood-stage cycle rather than general viability.

    Evidence Conditional knockdown in P. falciparum with schizont-arrest and membrane-integrity readouts, plus physical-release rescue and PKG-inhibitor epistasis

    PMID:20466936

    Open questions at the time
    • The direct molecular event blocked by CDPK5 loss was not identified
    • Kinase substrates were unknown
    • Relationship to PKG was defined by epistasis but not mechanistically
  2. 2014 Medium

    Linking CDPK5 to pyrazoleamide resistance placed the kinase within a druggable pathway and connected it to PfATP4 biology.

    Evidence Selection of resistant P. falciparum, whole-genome sequencing, and gene-transfer experiments showing CDPK5 plus PfATP4 mutations confer full resistance

    PMID:25422853

    Open questions at the time
    • The mechanistic role of the CDPK5 mutation in resistance is unresolved
    • Whether resistance reflects altered kinase activity is unknown
    • Direct interaction between CDPK5 and PfATP4 not demonstrated
  3. 2018 High

    Identifying microneme discharge as the CDPK5-dependent step defined the molecular mechanism of the egress block and positioned CDPK5 relative to PKG.

    Evidence Conditional knockdown with microneme-marker colocalization, PKG-hyperactivation rescue, and physical-disruption rescue in P. falciparum schizonts

    PMID:29487234

    Open questions at the time
    • Direct substrates mediating microneme discharge not identified
    • How CDPK5 and PKG signals converge biochemically unknown
    • Calcium signal activating CDPK5 not defined
  4. 2020 Medium

    Phosphoproteomic profiling began defining the CDPK5 substrate landscape, nominating membrane and transport proteins including PfNPT1.

    Evidence Label-free quantitative phosphoproteomics on CDPK5 conditional-knockdown P. falciparum schizonts, with fluorescence localization of PfNPT1

    PMID:31915223

    Open questions at the time
    • PfNPT1 substrate relationship not confirmed by in vitro kinase assay
    • Reduced phosphosites may be indirect
    • Functional link between candidate substrates and microneme discharge not established
  5. 2020 Medium

    Extending analysis to pre-erythrocytic stages showed CDPK5 function is not restricted to blood-stage egress but recurs across the life cycle.

    Evidence Conditional depletion in P. berghei sporozoites and liver stages with motility assays, cGMP rescue, and stage-specific immunofluorescence

    PMID:32866196

    Open questions at the time
    • Substrates in sporozoite/liver stages not identified
    • Whether the merosome-release role uses the same microneme mechanism as blood-stage egress unknown
    • Single-lab evidence

Open questions

Synthesis pass · forward-looking unresolved questions
  • How CDPK5 is activated by calcium and which direct substrates couple its kinase activity to microneme discharge remain the central open questions.
  • No in vitro-validated direct substrate
  • Mechanism of biochemical convergence with PKG unresolved
  • Upstream calcium signal and regulation undefined

Mechanism profile

Synthesis pass · controlled-vocabulary classification
Partners
PFATP4 (CO-MUTATED IN PYRAZOLEAMIDE RESISTANCE) [#3]PFNPT1 (CANDIDATE SUBSTRATE) [#2]PFPKG (CGMP-DEPENDENT PROTEIN KINASE; FUNCTIONAL/EPISTATIC COOPERATION) [#0, #1]

Evidence

Reading pass · 5 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2010 CDPK5 (PfCDPK5) is expressed in invasive merozoite forms and is essential for parasite egress from erythrocytes; conditional knockdown results in arrest as mature schizonts with intact membranes despite normal maturation of egress proteases and invasion ligands. Merozoites physically released from stalled schizonts retain invasion competence, separating egress and invasion pathways. The egress arrest is downstream of PfPKG function and independent of protease processing. Conditional knockdown with specific phenotypic readout (schizont arrest, membrane integrity assay, physical release rescue); genetic epistasis with PKG inhibitor Science High 20466936
2018 CDPK5 colocalizes with micronemes in P. falciparum schizonts and is required for microneme discharge; failure of microneme release is the molecular mechanism underlying the egress block observed upon CDPK5 knockdown. CDPK5 cooperates with PfPKG to fully activate the protease cascade critical for egress, and hyperactivation of PfPKG can overcome the CDPK5-dependent arrest, restoring microneme release. Conditional knockdown + colocalization (live imaging/IFA with microneme markers) + rescue by PKG hyperactivation + physical disruption rescue assay; genetic epistasis with PKG mBio High 29487234
2020 Phosphoproteomic profiling of CDPK5-deficient late schizonts identified 58 phosphorylation sites on 50 proteins significantly reduced in the absence of CDPK5, including PfNPT1 (a novel putative transporter localized to the parasite plasma membrane) as a potential CDPK5 substrate. Gene ontology analysis of affected proteins showed enrichment for transmembrane/membrane-associated proteins and transport activity. Label-free quantitative phosphoproteomics (mass spectrometry) on synchronized CDPK5 conditional-knockdown parasites; subcellular localization of PfNPT1 by fluorescence microscopy mSphere Medium 31915223
2014 Mutations in CDPK5 (together with PfATP4) are necessary to confer full resistance to pyrazoleamide antimalarial compounds, implicating CDPK5 in the pathway targeted by these drugs; whole-genome sequencing of resistant parasites and gene-transfer experiments established this genotype–resistance relationship. Selection of drug-resistant parasites, whole-genome sequencing, gene transfer Nature Communications Medium 25422853
2020 In P. berghei, CDPK5 is required for optimal sporozoite motility and hepatocyte invasion; elevated cGMP can compensate for loss of CDPK5 during sporozoite invasion. CDPK5 expression is downregulated after sporozoite invasion but reappears in late liver stages and merosomes; depletion of CDPK5 in liver stages/merosomes implicates it in merosome formation/release and delays initiation of the erythrocytic cycle. Genetic depletion (conditional knockdown) of CDPK5 in P. berghei sporozoites and liver stages; motility assays; cGMP rescue experiments; immunofluorescence for stage-specific expression PLoS Pathogens Medium 32866196

Source papers

Stage 0 corpus · 7 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2010 A plant-like kinase in Plasmodium falciparum regulates parasite egress from erythrocytes. Science (New York, N.Y.) 245 20466936
2014 Pyrazoleamide compounds are potent antimalarials that target Na+ homeostasis in intraerythrocytic Plasmodium falciparum. Nature communications 104 25422853
2018 Calcium-Dependent Protein Kinase 5 Is Required for Release of Egress-Specific Organelles in Plasmodium falciparum. mBio 64 29487234
2016 Reduced Activity of Mutant Calcium-Dependent Protein Kinase 1 Is Compensated in Plasmodium falciparum through the Action of Protein Kinase G. mBio 37 27923926
2020 Overlapping and distinct roles of CDPK family members in the pre-erythrocytic stages of the rodent malaria parasite, Plasmodium berghei. PLoS pathogens 22 32866196
2020 Influence of Plasmodium falciparum Calcium-Dependent Protein Kinase 5 (PfCDPK5) on the Late Schizont Stage Phosphoproteome. mSphere 18 31915223
2018 In silico analysis of plasmodium falciparum CDPK5 protein through molecular modeling, docking and dynamics. Journal of theoretical biology 12 30409756