PF3D7_0318600

PfCPSF3 (PF3D7_0318600) is a homologue of the mammalian CPSF-73 subunit that functions in pre-mRNA 3′-end processing in Plasmodium falciparum, and it is the direct molecular target of the antimalarial benzoxaborole AN3661 (PMID:28262680). In vitro resistance selection and CRISPR-Cas9 introduction of point mutations into pfcpsf3 both recapitulated AN3661 resistance, and homology modelling placed the resistance-conferring residues in the predicted AN3661-binding active site; AN3661 treatment caused loss of trophozoite-expressed transcripts consistent with inhibition of 3′-end processing, an effect abolished in resistant parasites (PMID:28262680). Beyond its role as an AN3661 target in pre-mRNA processing, the available corpus establishes only that PF3D7_0318600 was identified as a component of the PfCRL4 ubiquitin E3 ligase complex (which also contains PfCullin-2, PfRbx1, and WD40 repeat proteins) by immunoprecipitation, without direct functional characterization of this subunit within that complex (PMID:38416790).

1. 2017 High

   It was unknown what protein mediated the antimalarial activity of the benzoxaborole AN3661; identifying PfCPSF3 as the direct target established both the drug's mechanism and a functional role for this protein in pre-mRNA 3′-end processing.

   Evidence In vitro resistance selection with CRISPR-Cas9 active-site mutagenesis, homology modelling, and transcript analysis in wild-type versus resistant parasites

   PMID:28262680

   Open questions at the time

   • No direct enzymatic reconstitution of PfCPSF3 endonuclease activity
   • Interaction with other CPSF subunits or the broader 3′-end processing machinery not mapped
   • AN3661 binding mode inferred from homology modelling rather than an experimental structure
2. 2024 Low

   Whether PF3D7_0318600 participates in complexes beyond RNA processing was unaddressed; it was identified as a member of the PfCRL4 E3 ubiquitin ligase complex, hinting at a role outside canonical 3′-end processing.

   Evidence Immunoprecipitation and sequence analysis in P. falciparum

   PMID:38416790

   Open questions at the time

   • Single Co-IP without reciprocal validation or functional follow-up on this subunit
   • The functional contribution of PF3D7_0318600 within PfCRL4 is undefined
   • Relationship between the PfCRL4 association and the 3′-end processing role is unknown

• How PfCPSF3 integrates a canonical pre-mRNA 3′-end processing function with membership in a CRL4-like ubiquitin ligase complex, and its direct catalytic mechanism, remain unresolved.
• No experimental structure of PfCPSF3 or its AN3661 complex
• Endonuclease activity not biochemically reconstituted
• Functional role within PfCRL4 uncharacterized