DBP5

PF3D7_1459000 (DBP5) is a Plasmodium falciparum ATP-dependent RNA helicase characterized in vitro as possessing MgCl2- and single-stranded-DNA-dependent ATPase activity, unwinding duplex substrates in both 5′→3′ and 3′→5′ directions in the presence of Mg2+, Mn2+, or Zn2+, and preferentially unwinding poly(A) RNA substrates; its Q motif and helicase motifs I, Ia, Ib, and II are required for both helicase and ATPase activities (PMID:26537038). These catalytic activities are inhibited in vitro by DNA-intercalating agents including netropsin (IC50 3.2 µM), DAPI, ethidium bromide, and nogalamycin, which are thought to impede enzyme translocation (PMID:26537038). In asexual blood stages, DBP5 has been detected as a nuclear interaction partner of the chromatin-associated proteins PfMORC (PMID:39412522) and PfSET10 (PMID:39445823), placing it in proximity to chromatin modulation and mRNA-processing machinery. Beyond its in vitro enzymatic properties and these proteomic associations, the cellular role of DBP5 — including any function in mRNA export — has not been experimentally established in Plasmodium in the available corpus.

1. 2015 Medium

   Whether the P. falciparum Dbp5 homolog is a catalytically active helicase was unknown; recombinant enzyme assays established it as an ATP-dependent RNA helicase with defined cofactor requirements and mapped the motifs essential for catalysis.

   Evidence In vitro helicase and ATPase assays with recombinant protein and truncation mutagenesis of conserved motifs

   PMID:26537038

   Open questions at the time

   • Enzymatic characterization reported secondhand via a review; primary source not directly in corpus
   • Physiological RNA substrates and in vivo function not addressed
   • No cellular localization or knockdown/knockout phenotype established
2. 2015 Low

   To probe the enzyme's mechanism and druggability, small-molecule inhibitors were tested, showing that DNA-intercalating agents block DBP5 unwinding and ATPase activity.

   Evidence In vitro helicase and ATPase inhibition assays with recombinant protein using DAPI, ethidium bromide, netropsin, and nogalamycin

   PMID:26537038

   Open questions at the time

   • Result reported secondhand in a review; primary source not directly in corpus
   • Inhibition is via nonspecific nucleic-acid intercalation, not selective targeting of DBP5
   • No cellular or parasite-growth validation of inhibition
3. 2024 Low

   To situate DBP5 in a cellular pathway, interactomics identified it as a nuclear associate of chromatin-linked proteins, linking the helicase to chromatin/mRNA-processing machinery rather than characterizing it in isolation.

   Evidence Co-immunoprecipitation/mass spectrometry with PfMORC as bait, and TurboID proximity labeling with PfSET10, in asexual blood stages

   PMID:39412522 PMID:39445823

   Open questions at the time

   • Single pulldown with marginal significance and proximity labeling without reciprocal validation or direct-binding confirmation for DBP5
   • Functional consequence of the PfMORC and PfSET10 associations not tested
   • Does not establish DBP5's role in mRNA export or chromatin regulation

• The in vivo cellular function of DBP5 in Plasmodium — whether it acts in mRNA export, chromatin-associated processing, or another process — remains unestablished.
• No knockdown/knockout or conditional depletion phenotype
• No demonstration of an mRNA export role in Plasmodium
• Functional significance of PfMORC/PfSET10 associations untested