PF3D7_0705900

PF3D7_0705900 is annotated as a putative ATP synthase subunit C of Plasmodium falciparum, and the available evidence characterizes it only as a component of the mitochondrial ATP synthase complex rather than as an individually dissected protein. An epitope-tagged version of subunit C localizes to the mitochondrion of blood-stage P. falciparum, and blue native gel electrophoresis places the assembled ATP synthase at greater than 1 MDa, consistent with a dimeric complex that likely contains additional non-canonical subunits (PMID:21984828). Functional and genetic manipulation has been performed only on other subunits of the same complex: the β and γ subunit genes resisted disruption in blood-stage P. falciparum, implying essentiality of the complex (PMID:21984828), and in P. berghei the β-subunit is dispensable for asexual blood-stage growth but essential for mosquito-stage viability through the female, mitochondrion-carrying line (PMID:25831536). In P. falciparum, mitochondrial ATP synthesis by this complex is required for completion of male gametogenesis, a transmission-stage role distinct from bulk cytoplasmic ATP supply (PMID:39550509). No experiment in the available corpus has individually manipulated subunit C to assign it a catalytic or structural function separate from the complex; beyond its mitochondrial localization and complex membership (PMID:21984828), subunit C itself remains uncharacterized.

1. 2009 Low

   Before direct study, the composition of the Plasmodium F(o) sector was uncertain; bioinformatic fingerprinting of membrane-anchor candidates began mapping the divergent F(o) subunit landscape in which subunit C operates.

   Evidence Computational/structural fingerprint analysis integrating proteomics from other protists to identify divergent subunit a/b candidates in Plasmodium

   PMID:19682605

   Open questions at the time

   • Purely computational; no biochemical or genetic experiment on PF3D7_0705900
   • Addresses subunit a/b candidates, not subunit C directly
   • Divergence of subunit C itself not assessed
2. 2011 Medium

   It was unknown where subunit C resides and how the complex assembles; tagging and native-gel analysis placed subunit C in the mitochondrion within a >1 MDa dimeric ATP synthase and indicated the complex is essential in blood stages.

   Evidence Epitope-tagging of seven canonical subunits in transgenic P. falciparum, immunofluorescence, blue native PAGE of mitochondrial membranes, and attempted disruption of β/γ subunits

   PMID:21984828

   Open questions at the time

   • Subunit C examined as one of seven subunits, not functionally dissected
   • Essentiality inferred from β/γ disruption failure, not from subunit C itself
   • Additional non-canonical subunits implied by mass but not identified
3. 2015 Medium

   Whether the ATP synthase complex is required across the life cycle was unresolved; β-subunit knockout in P. berghei showed the complex is dispensable for asexual blood-stage growth but essential for mosquito-stage viability through the female lineage.

   Evidence β-subunit gene knockout in P. berghei, mosquito transmission assays, and complementation cross with a male-deficient strain

   PMID:25831536

   Open questions at the time

   • Phenotype attributed to β subunit, not subunit C
   • Shown in P. berghei, not P. falciparum
   • Does not establish whether subunit C is required for these stages
4. 2024 Medium

   The stage-specific function of the complex needed clarification; mitochondrial ATP synthesis was shown to be essential for male gametogenesis in P. falciparum, distinct from general cytoplasmic ATP supply.

   Evidence Sex-specific labeling, mitochondrial dye labeling, a genetically encoded ratiometric ATP sensor, and pharmacological inhibition of mitochondrial ATP synthesis in P. falciparum gametocytes

   PMID:39550509

   Open questions at the time

   • Function attributed to the complex, not subunit C individually
   • Mechanism linking ATP synthesis to gametogenesis not defined
   • No manipulation of subunit C to test its contribution

• It remains unknown what specific catalytic or structural role subunit C (PF3D7_0705900) plays, since no experiment has individually manipulated the subunit apart from the broader ATP synthase complex.
• No individual knockout/knockdown of subunit C
• No structural placement within the assembled complex
• No assay of subunit C contribution to catalysis or dimerization