ARP6

ARP6 (PF3D7_0719300) is a nuclear actin-related protein of P. falciparum implicated in chromatin remodeling through its participation in a conserved histone-variant deposition machinery (PMID:32552779, PMID:38564734). It physically interacts with the nuclear actin-related protein PfArp4, with which it co-localizes in the nucleus of blood-stage parasites by reciprocal co-IP and co-IFA (PMID:32552779). ARP6 is a subunit of the PfSWR1 complex, identified through affinity pulldown of the shared NuA4/SWR1 subunit PfEAF2 followed by LC-MS/MS, placing it within a complex associated with H2A.Z/H2B.Z deposition (PMID:38564734). Beyond this complex membership and the PfArp4 interaction, no direct functional assay of ARP6 itself has been characterized in the available corpus.

1. 2020 Medium

   Establishing whether ARP6 partners with other nuclear actin-related proteins addressed whether it operates within a nuclear protein assembly rather than acting alone.

   Evidence Co-IFA and reciprocal co-IP in CRISPR-Cas9-tagged transgenic P. falciparum blood-stage parasites

   PMID:32552779

   Open questions at the time

   • Does not define the functional consequence of the ARP6-PfArp4 interaction
   • Does not resolve which larger complex, if any, these proteins belong to
   • No direct assay of ARP6 activity or essentiality
2. 2024 Medium

   Determining the complex membership of ARP6 addressed which chromatin-remodeling machinery it contributes to, linking it to histone-variant deposition.

   Evidence GFP-trap affinity pulldown of PfEAF2::GFP with LC-MS/MS across three biological replicates and SAINT filtering in P. falciparum

   PMID:38564734

   Open questions at the time

   • Complex membership established but no direct functional assay of ARP6 within PfSWR1
   • ARP6's specific contribution to H2A.Z/H2B.Z deposition is not demonstrated
   • No structural or stoichiometric definition of ARP6 in the complex

• The direct molecular function of ARP6 within the PfSWR1 complex and its requirement for parasite chromatin state remain unresolved.
• No knockdown/knockout phenotype for ARP6 itself reported
• No demonstration that ARP6 is required for histone variant deposition
• No mapping of ARP6 genomic occupancy or binding partners beyond PfArp4 and complex co-members