RUVB1

PF3D7_0809700 (RUVB1) encodes a nucleic-acid-stimulated AAA+ ATPase and DNA helicase of Plasmodium falciparum (PMID:23219504). Recombinant PfRuvB1 hydrolyzes ATP in a reaction significantly stimulated by single-stranded DNA and unwinds DNA with a preferential 5′-to-3′ translocation polarity (PMID:23219504). The protein is constitutively expressed across all stages of the intraerythrocytic cycle and localizes predominantly to the nucleus, consistent with a role acting on DNA substrates (PMID:23219504). Despite being a RuvB-family member, PfRuvB1 does not interact with PfRuvB2 in vitro—PfRuvB2 associates only with PfRuvB3—placing PfRuvB1 outside the PfRuvB2/PfRuvB3 complex and indicating it functions in a distinct assembly or context (PMID:24161468). Its enzymatic activities are pharmacologically tractable: novobiocin considerably inhibits its ATPase and potently inhibits its helicase activity, likely by competing at the ATP-binding site, while actinomycin and ethidium bromide are potent helicase inhibitors (PMID:24934654). Beyond these in vitro biochemical and localization findings, the cellular pathway and physiological substrates of PF3D7_0809700 have not been characterized in the available corpus.

1. 2012 High

   Establishing whether the RuvB1 gene product is an active enzyme, biochemical characterization showed it is a bona fide ssDNA-stimulated ATPase and a directional DNA helicase, defining its core molecular activity.

   Evidence In vitro ATPase assay and DNA unwinding assay with recombinant protein, establishing ssDNA stimulation and 5′→3′ directionality

   PMID:23219504

   Open questions at the time

   • Physiological DNA substrate not identified
   • No structural or mutagenesis data mapping the ATP/DNA-binding residues
   • Cellular pathway in which the helicase acts unknown
2. 2012 Medium

   Determining when and where the enzyme operates, expression and localization analysis showed it is constitutively present throughout the intraerythrocytic cycle and nuclear, consistent with a DNA-acting role.

   Evidence Stage-specific expression analysis and subcellular localization during the intraerythrocytic cycle

   PMID:23219504

   Open questions at the time

   • Method details of localization not fully specified
   • No functional link between nuclear localization and a specific DNA transaction
3. 2013 Medium

   Addressing whether PfRuvB1 partners with the other Plasmodium RuvB proteins, interaction assays showed it does not bind PfRuvB2 (which associates only with PfRuvB3), excluding PfRuvB1 from the PfRuvB2/PfRuvB3 complex.

   Evidence In vitro pulldown/binding assays between recombinant Plasmodium RuvB proteins

   PMID:24161468

   Open questions at the time

   • The actual protein partners or complex of PfRuvB1 remain unidentified
   • Negative interaction shown in vitro only, not in cellular context
4. 2014 Medium

   Probing pharmacological tractability, inhibition assays showed novobiocin blocks ATPase and helicase activity (likely via ATP-site competition) and identified actinomycin and ethidium bromide as potent helicase inhibitors, defining druggable enzymatic activities.

   Evidence In vitro ATPase and helicase inhibition assays with recombinant PfRuvB1 and defined chemical compounds

   PMID:24934654

   Open questions at the time

   • ATP-site competition mechanism inferred, not confirmed by mutagenesis or structure
   • No demonstration that inhibition translates to parasite killing

• The in vivo function, physiological substrates, protein partners, and the cellular DNA transaction served by PF3D7_0809700 remain undefined.
• No identification of the complex or partners PfRuvB1 does belong to
• No genetic/knockdown evidence for its cellular role
• No structural model