Affinage · Plasmodium

DPAP3

PF3D7_0404700 · dipeptidyl aminopeptidase 3

Annotated
2026-09-07
10 papers in source corpus 6 papers cited in narrative 6 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

DPAP3 (PF3D7_0404700) is a papain-fold cysteine dipeptidyl aminopeptidase of the P. falciparum blood stage whose enzymatic activity is required for efficient erythrocyte invasion (PMID:29768491). Recombinant DPAP3 possesses dipeptidyl aminopeptidase activity, and unlike other DPAPs it does not require removal of its internal prodomain for activation (PMID:29768491). It is expressed in schizonts and merozoites and localizes to apical organelles at the neck of the rhoptries that are distinct from micronemes, rhoptries, and dense granules, and it is secreted immediately before egress (PMID:29768491, PMID:29509772). Conditional knockout complemented with wild-type versus catalytically dead DPAP3 established that its catalytic activity is critical specifically at the step of initial parasite attachment to the red blood cell surface, but is dispensable for egress (PMID:29768491). An earlier chemical-genetic screen had placed DPAP3 upstream of PfSUB1 maturation and SERA5 processing during egress (PMID:18246061); this egress role was subsequently overturned, as both conditional knockdown and conditional knockout showed no effect on PfSUB1 substrate processing or egress, attributing the original phenotype to off-target inhibitor effects (PMID:29768491, PMID:29509772). The active-site specificity of DPAP3 has been mapped and distinguished from DPAP1 and mammalian cathepsin C, and inhibitor screening revealed a distinct allosteric regulatory site targeted by most non-competitive hits (PMID:31177613, PMID:31851699). The physiological substrates cleaved by DPAP3 during invasion have not been established in the available corpus.

Mechanistic history

Synthesis pass · year-by-year structured walk · 5 steps
  1. 2008 Medium

    To find proteases governing erythrocyte rupture, a forward chemical-genetic screen implicated DPAP3, initially placing it upstream of PfSUB1 maturation in the egress pathway.

    Evidence forward chemical genetic screen with >1,200 covalent protease inhibitors plus biochemical assay of SERA5 processing and PfSUB1 maturation in P. falciparum

    PMID:18246061

    Open questions at the time
    • Relied on inhibitors that were later shown to have off-target effects
    • No genetic validation of the egress role
    • Direct DPAP3 substrates not defined
  2. 2010 Medium

    To define which proteolytic events depend on DPAP3, global proteomic profiling with a selective inhibitor produced a first map of DPAP3-dependent processing at rupture.

    Evidence PROTOMAP mass spectrometry comparing selective DPAP3-inhibitor-treated versus untreated P. falciparum at rupture

    PMID:20943600

    Open questions at the time
    • Inhibitor-based, no genetic confirmation of substrate identity
    • Cannot distinguish direct DPAP3 substrates from downstream effects
  3. 2018 High

    To resolve DPAP3's true biochemical activity and function, recombinant enzymology, imaging, and conditional knockout with catalytic-mutant complementation established it as a prodomain-independent cysteine dipeptidyl aminopeptidase whose activity drives erythrocyte invasion, not egress.

    Evidence recombinant enzyme assay, super-resolution/time-lapse/immunoelectron microscopy, DiCre conditional knockout with wild-type and catalytic-mutant complementation, and flow cytometry invasion assays in P. falciparum

    PMID:29768491

    Open questions at the time
    • Physiological substrates cleaved during attachment not identified
    • Molecular mechanism linking catalytic activity to RBC attachment unresolved
    • No experimental structure of the enzyme
  4. 2018 High

    Independent conditional knockdown confirmed DPAP3 resides in apical organelles distinct from micronemes, rhoptries, and dense granules and is dispensable for PfSUB1 substrate processing and egress, directly overturning the earlier egress model.

    Evidence glmS ribozyme conditional knockdown with immunofluorescence co-localization, SUB1 substrate western blots, and egress assays in P. falciparum

    PMID:29509772

    Open questions at the time
    • Knockdown may leave residual protein
    • Does not identify the invasion-relevant substrates
  5. 2019 Medium

    To enable selective targeting, active-site specificity profiling distinguished DPAP3 from DPAP1 and cathepsin C, while inhibitor mechanism studies revealed a druggable allosteric site.

    Evidence positional scanning substrate and covalent inhibitor library screens with homology modelling/docking, and high-throughput inhibitor screening with mechanism-of-inhibition kinetics in P. falciparum

    PMID:31177613 PMID:31851699

    Open questions at the time
    • Allosteric site not structurally mapped
    • Homology model not validated by experimental structure
    • Selectivity profiling in vitro only

Open questions

Synthesis pass · forward-looking unresolved questions
  • The endogenous substrate(s) DPAP3 cleaves during merozoite attachment, and the molecular basis by which its aminopeptidase activity promotes initial RBC contact, remain undefined.
  • No genetically validated physiological substrate
  • Mechanistic link between catalysis and attachment unknown
  • No experimental structure

Mechanism profile

Synthesis pass · controlled-vocabulary classification
No controlled-vocabulary terms were assigned to this entry.

Evidence

Reading pass · 6 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2008 DPAP3 (PF3D7_0404700) was identified as a primary regulator of P. falciparum erythrocyte rupture using a forward chemical genetic screen with covalent serine/cysteine protease inhibitors. Inhibition of DPAP3 caused a block in proteolytic processing of SERA5 and reduced levels of mature PfSUB1, placing DPAP3 upstream of PfSUB1 maturation in the egress pathway. Forward chemical genetic screen with a library of >1,200 covalent protease inhibitors; biochemical assay of SERA5 processing and PfSUB1 maturation upon DPAP3 inhibition Nature chemical biology Medium 18246061
2010 Using a highly selective DPAP3 inhibitor in a global proteolytic profiling (PROTOMAP) approach, specific protein substrates whose processing depends on DPAP3 activity were identified during P. falciparum erythrocyte rupture, providing a first global map of proteolytic events regulated by DPAP3 at this stage. PROTOMAP proteomics platform combined with selective DPAP3 chemical inhibitor; mass spectrometry-based peptographs comparing inhibitor-treated vs. untreated parasites at rupture Molecular & cellular proteomics : MCP Medium 20943600
2018 Recombinantly expressed DPAP3 (PF3D7_0404700) was shown to possess dipeptidyl aminopeptidase (cysteine protease) activity. Unlike other DPAPs, removal of its internal prodomain is not required for enzymatic activation. By super-resolution, time-lapse fluorescence, and immunoelectron microscopy, DPAP3 localizes to apical organelles closely associated with the neck of the rhoptries and is secreted immediately before parasite egress. Conditional knockout coupled with complementation using wild-type or catalytically mutant DPAP3 demonstrated that DPAP3 enzymatic activity is critical for efficient erythrocyte invasion, specifically at the step of initial parasite attachment to the red blood cell surface, but is NOT required for parasite egress. Recombinant protein expression and enzyme activity assay; super-resolution microscopy, time-lapse fluorescence microscopy, immunoelectron microscopy; conditional knockout (DiCre system) with wild-type and catalytic mutant complementation; flow cytometry invasion assay PLoS pathogens High 29768491
2018 Conditional knockdown of DPAP3 (PF3D7_0404700) using a glmS ribozyme system showed that DPAP3 is expressed in schizonts and merozoites and localizes to organelles distinct from micronemes, rhoptries, and dense granules. DPAP3 knockdown did not affect trafficking of apical proteins, processing of PfSUB1 substrates, parasite maturation, or egress from red blood cells, directly contradicting its previously proposed role in egress and SUB1 maturation. Conditional knockdown via glmS ribozyme-based RNA degradation; immunofluorescence co-localization with known organelle markers; western blot of SUB1 substrate processing; parasite egress assay PloS one High 29509772
2019 Peptide-based substrate library screening and covalent inhibitor library screening characterized the amino acid specificity of DPAP3 (PF3D7_0404700) active site, revealing differences between substrate preferences and inhibitor preferences. Homology modelling and docking provided structural explanations for specificity differences between DPAP1, DPAP3, and mammalian cathepsin C, enabling development of highly selective DPAP3 inhibitors. Positional scanning substrate library screening; covalent inhibitor library screening; homology modelling and molecular docking The FEBS journal Medium 31177613
2019 High-throughput screening identified novel DPAP3 (PF3D7_0404700) inhibitors; mechanism-of-inhibition studies showed that most hits act as allosteric (non-competitive) inhibitors rather than competitive active-site inhibitors, demonstrating that an allosteric regulatory site exists on DPAP3. High-throughput enzymatic inhibitor screen; mechanism-of-inhibition kinetics assays PloS one Medium 31851699

Source papers

Stage 0 corpus · 10 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2008 Identification of proteases that regulate erythrocyte rupture by the malaria parasite Plasmodium falciparum. Nature chemical biology 202 18246061
2011 Falcipains and other cysteine proteases of malaria parasites. Advances in experimental medicine and biology 116 21660657
2010 Functional studies of Plasmodium falciparum dipeptidyl aminopeptidase I using small molecule inhibitors and active site probes. Chemistry & biology 53 20797610
2010 Global profiling of proteolysis during rupture of Plasmodium falciparum from the host erythrocyte. Molecular & cellular proteomics : MCP 51 20943600
2018 Plasmodium falciparum dipeptidyl aminopeptidase 3 activity is important for efficient erythrocyte invasion by the malaria parasite. PLoS pathogens 29 29768491
2018 The cysteine protease dipeptidyl aminopeptidase 3 does not contribute to egress of Plasmodium falciparum from host red blood cells. PloS one 16 29509772
2019 Characterization of P. falciparum dipeptidyl aminopeptidase 3 specificity identifies differences in amino acid preferences between peptide-based substrates and covalent inhibitors. The FEBS journal 8 31177613
2019 Identification of Plasmodium dipeptidyl aminopeptidase allosteric inhibitors by high throughput screening. PloS one 5 31851699
2023 Design and Molecular Docking Studies of N-Mannich Base Derivatives of Primaquine Bearing Isatin on the Targets involved in the Pathophysiology of Cerebral Malaria. CNS & neurological disorders drug targets 2 35507781
2025 Therapeutic Targeting and Role of Cysteine Proteases in the Life Cycle of Malaria Parasite. Current medicinal chemistry 0 39185645