Affinage · Plasmodium

DHS

PF3D7_1412600 · deoxyhypusine synthase

Annotated
2026-09-08
20 papers in source corpus 8 papers cited in narrative 8 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

DHS (PF3D7_1412600) catalyzes the first committed step of hypusine biosynthesis in Plasmodium falciparum, transferring an aminobutyl moiety from spermidine to the eIF-5A precursor to generate deoxyhypusine-eIF-5A, with deoxyhypusine hydroxylase completing the modification (PMID:19740108, PMID:17591443). Recombinant PfDHS is bifunctional, additionally exhibiting homospermidine synthase activity, and is potently inhibited by GC7 (Ki 0.1 µM) (PMID:17591443). Its physiological substrate is the P. falciparum eIF-5A precursor (PMID:15279952). PfDHS is cytoplasmic in asexual-stage parasites, and conditional glmS knockdown reduces hypusinated eIF-5A and impairs proliferation without altering global protein synthesis, establishing it as essential and druggable (PMID:31024761); genetic disruption of the P. berghei ortholog likewise fails except upon episomal complementation (PMID:27516964), and shRNA knockdown reduces parasitemia in vivo (PMID:22694849). Beyond hypusine-pathway biochemistry, its localization, and essentiality, no further mechanistic detail (e.g. structure, regulatory partners) has been characterized in the available corpus.

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 2004 Medium

    Before its enzyme was characterized, the identity of the DHS substrate in P. falciparum was established by showing the P. falciparum eIF-5A precursor can be hypusinated, defining the target of the pathway DHS initiates.

    Evidence Radioactive [1,8-³H]-spermidine incorporation assay with recombinant P. falciparum eIF-5A precursor and human DHS

    PMID:15279952

    Open questions at the time
    • Used human DHS rather than PfDHS itself as the modifying enzyme
    • Did not identify the specific modified lysine on Plasmodium eIF-5A
  2. 2007 Medium

    Direct reconstitution with purified recombinant protein established that PF3D7_1412600 is itself a bifunctional deoxyhypusine synthase / homospermidine synthase and defined GC7 as a high-affinity inhibitor, converting an inferred activity into a demonstrated enzyme.

    Evidence In vitro enzymatic assay with Ni-purified truncated His-tagged PfDHS from strain NF54; inhibitor kinetics (GC7 Ki 0.1 µM)

    PMID:17591443

    Open questions at the time
    • Truncated construct; full-length behavior untested
    • Biological role of the homospermidine synthase activity in the parasite unknown
  3. 2008 Medium

    To test druggability, an alternative inhibitor was assayed, showing CNI-1493 inhibits purified PfDHS and clears parasites in culture, linking enzyme inhibition to an antiplasmodial phenotype.

    Evidence Enzymatic inhibition assay with purified PfDHS plus in vitro infected-erythrocyte growth assay

    PMID:18256853

    Open questions at the time
    • Only ~3-fold inhibition at 2 µM in vitro; weak potency
    • Parasite clearance not proven to be on-target via genetic controls
  4. 2009 Medium

    Enzymatic studies confirmed DHS acts as a discrete first step in the two-enzyme hypusine pathway upstream of DOHH, ordering the biosynthetic route.

    Evidence In vitro enzymatic studies of aminobutyl transfer from spermidine to eIF-5A

    PMID:17591443 PMID:19740108

    Open questions at the time
    • Kinetic coupling between DHS and DOHH in vivo not characterized
  5. 2012 Medium

    Knockdown moved DHS from an in vitro enzyme to a proliferation requirement, showing reduced DHS lowers hypusinated eIF-5A and parasitemia in a blood-stage infection model.

    Evidence shRNA knockdown in 293T cells and transgenic P. berghei ANKA; RT-PCR, Western blot, in vivo mouse infection

    PMID:22694849

    Open questions at the time
    • shRNA-based Plasmodium knockdown is mechanistically atypical
    • Host iNOS link not mechanistically dissected
  6. 2016 Medium

    Genetic essentiality was reinforced by the failure to disrupt the P. berghei dhs ortholog except with an episomal copy, indicating an indispensable asexual blood-stage function.

    Evidence Targeted gene disruption (failed) and knock-in in P. berghei with genetic selection

    PMID:27516964

    Open questions at the time
    • Essentiality inferred from failed knockout rather than conditional depletion
    • Stage-specific requirement beyond asexual blood stage untested
  7. 2019 High

    A rigorous conditional-knockdown study established PfDHS as cytoplasmic, essential, and druggable, and pinpointed hypusinated eIF-5A rather than bulk translation as the affected downstream node.

    Evidence glmS riboswitch knockdown, confocal microscopy, hypusination and nascent-protein-synthesis assays, competitive growth and chemogenomic profiling in P. falciparum 3D7

    PMID:31024761

    Open questions at the time
    • Downstream targets of hypusinated eIF-5A that drive the growth defect not identified
    • No structural basis for essentiality
  8. 2022 Medium

    Testing an allosteric human DHS inhibitor showed it does not effectively target PfDHS, revealing structural divergence at the allosteric site and constraining inhibitor design strategy.

    Evidence Dose-dependent enzymatic assay with purified PfDHS, chemogenomic profiling with transgenic P. falciparum, homology modeling

    PMID:35458660

    Open questions at the time
    • Negative result on one compound class; active-site-directed inhibition not addressed
    • No experimental structure of the PfDHS allosteric site

Open questions

Synthesis pass · forward-looking unresolved questions
  • The structural basis of PfDHS catalysis, the biological role of its homospermidine synthase activity, and the downstream effectors of hypusinated eIF-5A that mediate essentiality remain undefined.
  • No experimental structure of PfDHS
  • Function of homospermidine synthase activity in the parasite unknown
  • eIF-5A-dependent effectors driving the growth defect unidentified

Mechanism profile

Synthesis pass · controlled-vocabulary classification
Partners
DEOXYHYPUSINE HYDROXYLASE (DOHH; DOWNSTREAM PATHWAY ENZYME)EIF-5A PRECURSOR (SUBSTRATE)

Evidence

Reading pass · 8 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2007 Truncated DHS from P. falciparum strain NF54 (PF3D7_1412600), expressed as a His-fusion protein and purified by Ni-affinity chromatography, was shown to be a bifunctional enzyme with both deoxyhypusine synthase activity (modifying eIF-5A from P. vivax) and homospermidine synthase activity (0.047 pkatal/mg protein). The DHS inhibitor GC7 inhibited the enzyme with a Ki of 0.1 µM, 2000-fold lower than the non-guanylated derivative 1,7-diaminoheptane. In vitro enzymatic assay with purified recombinant protein; Ni-affinity chromatography; inhibitor kinetics Bioorganic & medicinal chemistry Medium 17591443
2009 DHS from P. falciparum (PF3D7_1412600) was shown by enzymatic studies to catalyze the transfer of an aminobutyl moiety from spermidine to eIF-5A, modifying it to deoxyhypusine-containing eIF-5A; this was confirmed as a discrete first step in the two-enzyme hypusine biosynthesis pathway, with deoxyhypusine hydroxylase (DOHH) completing the modification. Enzymatic studies (in vitro); structured digital abstract citing MI:0414/MI:0415 The FEBS journal Medium 17591443 19740108
2008 Purified P. falciparum DHS (PF3D7_1412600) was inhibited by CNI-1493 with approximately 3-fold inhibition at 2 µM in a direct enzymatic assay; in vitro treatment of P. falciparum-infected erythrocytes with 200 µM CNI-1493 caused parasite clearance within 2 days, attributed to DHS inhibition. Enzymatic inhibition assay with purified DHS protein; in vitro parasite culture inhibition assay Parasitology research Medium 18256853
2019 PfDHS (PF3D7_1412600) was localized to the cytoplasm of asexual-stage P. falciparum parasites by confocal microscopy. Conditional knockdown via glmS riboswitch reduced PfDHS protein ~5-fold, leading to a significant reduction in hypusinated eIF-5A without affecting global protein synthesis, and caused a significant parasite growth defect. Attenuated parasites showed increased sensitivity to GC7 (N1-guanyl-1,7-diaminoheptane). These results establish PfDHS as essential for parasite proliferation and validate it as a druggable antimalarial target. glmS riboswitch conditional knockdown; confocal microscopy; Western immunoblot; hypusination assay; nascent protein synthesis assay; competitive growth assay; chemogenomic profiling PeerJ High 31024761
2012 In vitro knockdown of DHS (PF3D7_1412600) in 293T cells using plasmodial DHS-specific shRNA reduced dhs mRNA and DHS protein levels. In vivo, P. berghei ANKA schizonts transgenic for DHS-specific shRNA showed reduced parasitemia 2–9 days post-infection, absent DHS protein on Western blot, and reduced hypusinated eIF-5A, confirming that DHS is required for parasite proliferation during blood-stage infection. DHS knockdown was also linked to reduced iNOS induction in the host. RNAi/shRNA knockdown in mammalian cells and transgenic P. berghei; RT-PCR; Western blot; in vivo mouse infection model BMC microbiology Medium 22694849
2016 Attempted full gene disruption of dhs (PF3D7_1412600 ortholog) in P. berghei was unsuccessful; only parasites retaining an episomal copy of the dhs gene were recovered. A knock-in strategy yielded viable recombinant parasites, suggesting that DHS performs an essential function during asexual blood-stage development. Targeted gene disruption (knock-out attempt) and knock-in in P. berghei; genetic selection FEBS open bio Medium 27516964
2022 In dose-dependent enzymatic assays with purified recombinant P. falciparum DHS protein (PF3D7_1412600), the allosteric human DHS inhibitor 6-bromo-N-(1H-indol-4yl)-1-benzothiophene-2-carboxamide achieved only 45% inhibition at 0.4 µM, and chemogenomic profiling with transgenic P. falciparum lines showed that the weak in vitro antiplasmodial activity could not be attributed to Pfdhs targeting. Homology modeling indicated significant structural differences in the allosteric site between human DHS and PfDHS. In vitro enzymatic inhibition assay with purified recombinant PfDHS; chemogenomic profiling with transgenic parasites; homology modeling Molecules (Basel, Switzerland) Medium 35458660
2004 The P. falciparum eIF-5A precursor protein (the substrate of DHS/PF3D7_1412600) was shown to serve as a substrate for human deoxyhypusine synthase in radioactive incorporation studies with [1,8-³H]-spermidine, confirming that PF3D7_1412600's substrate in P. falciparum is the eIF-5A precursor. Radioactive spermidine incorporation assay (in vitro); recombinant protein expression Molecular and biochemical parasitology Medium 15279952

Source papers

Stage 0 corpus · 20 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2001 Effect of drugs inhibiting spermidine biosynthesis and metabolism on the in vitro development of Plasmodium falciparum. Parasitology research 34 11728024
2015 From Protease to Decarboxylase: THE MOLECULAR METAMORPHOSIS OF PHOSPHATIDYLSERINE DECARBOXYLASE. The Journal of biological chemistry 33 25724650
2003 Targeting enzymes involved in spermidine metabolism of parasitic protozoa--a possible new strategy for anti-parasitic treatment. Parasitology research 25 14530966
2008 The guanylhydrazone CNI-1493: an inhibitor with dual activity against malaria-inhibition of host cell pro-inflammatory cytokine release and parasitic deoxyhypusine synthase. Parasitology research 23 18256853
2007 Modification of eukaryotic initiation factor 5A from Plasmodium vivax by a truncated deoxyhypusine synthase from Plasmodium falciparum: An enzyme with dual enzymatic properties. Bioorganic & medicinal chemistry 20 17591443
2004 Translation initiation factor eIF-5A from Plasmodium falciparum. Molecular and biochemical parasitology 15 15279952
2012 In vitro and in vivo silencing of plasmodial dhs and eIf-5a genes in a putative, non-canonical RNAi-related pathway. BMC microbiology 13 22694849
2009 Completing the hypusine pathway in Plasmodium. The FEBS journal 13 19740108
2006 Piperidones with activity against Plasmodium falciparum. Parasitology research 12 16550432
2023 The Role of Spermidine and Its Key Metabolites in Important, Pathogenic Human Viruses and in Parasitic Infections Caused by Plasmodium falciparum and Trypanosoma brucei. Biomolecules 10 37238673
2006 Cloning, expression and functional activity of deoxyhypusine synthase from Plasmodium vivax. BMC microbiology 10 17042947
2020 Inhibition of EIF-5A prevents apoptosis in human cardiomyocytes after malaria infection. Amino acids 9 32367435
2019 Validation of Plasmodium falciparum deoxyhypusine synthase as an antimalarial target. PeerJ 9 31024761
2016 A suggested vital function for eIF-5A and dhs genes during murine malaria blood-stage infection. FEBS open bio 9 27516964
2013 Computational and experimental analysis identified 6-diazo-5-oxonorleucine as a potential agent for treating infection by Plasmodium falciparum. Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases 9 24121016
2004 The efficacy of inhibitors involved in spermidine metabolism in Plasmodium falciparum, Anopheles stephensi and Trypanosoma evansi. Parasitology research 7 15278440
2003 Spermidine metabolism in parasitic protozoa--a comparison to the situation in prokaryotes, viruses, plants and fungi. Folia parasitologica 7 12735718
2011 A rapid and robust assay for the determination of the amino acid hypusine as a possible biomarker for a high-throughput screening of antimalarials and for the diagnosis and therapy of different diseases. Amino acids 6 21360085
2024 An experimental target-based platform in yeast for screening Plasmodium vivax deoxyhypusine synthase inhibitors. PLoS neglected tropical diseases 2 39621767
2022 Investigation of an Allosteric Deoxyhypusine Synthase Inhibitor in P. falciparum. Molecules (Basel, Switzerland) 0 35458660