CAPD3

CAPD3 (PF3D7_1135600) is a subunit of the condensin II complex in Plasmodium falciparum, a complex that assembles specifically during mature schizogony and male gametogenesis but not during early schizogony, when SMC2/SMC4 instead localize to centromeres without forming condensin I or II (PMID:32049018). This developmental restriction places CAPD3-containing condensin II in stages associated with chromosome condensation. Consistent with such a role, the CAPD3 transcript is expressed during late zygote/early ookinete progression in the mosquito midgut, a timing compatible with meiotic chromosome condensation (PMID:36847501). Beyond its membership in the condensin II complex (PMID:32049018), no direct mechanistic experiments on CAPD3 itself have been reported in the available corpus.

1. 2020 Medium

   Establishing when condensin II assembles resolved whether P. falciparum uses distinct condensin complexes at different points in its cell cycle, and placed CAPD3 as a subunit active only in specific stages.

   Evidence Co-immunoprecipitation, fluorescence microscopy of SMC2/SMC4 with an NDC80 centromere marker, and ChIP-seq in P. falciparum

   PMID:32049018

   Open questions at the time

   • No direct experiment on CAPD3 itself beyond identifying it as a condensin II subunit
   • The chromosomal targets and condensation activity attributable specifically to CAPD3 are not defined
   • Loss-of-function phenotype for CAPD3 is not established
2. 2023 Low

   Mapping the developmental timing of CAPD3 transcription tested whether the gene is expressed at a stage consistent with meiotic condensation in the mosquito.

   Evidence Single-cell transcriptomics with pseudotime analysis of P. falciparum development in the mosquito midgut

   PMID:36847501

   Open questions at the time

   • Transcriptomic profiling only; no functional or biochemical assay of CAPD3 was performed
   • Protein-level expression and localization at this stage were not shown
   • A causal link between CAPD3 and meiotic chromosome condensation was not tested

• The direct biochemical function, essential interactions, and loss-of-function phenotype of CAPD3 remain uncharacterized independently of the condensin II complex.
• No CAPD3-specific knockout or knockdown phenotype
• No structural or biochemical characterization of CAPD3 within condensin II
• No demonstration that CAPD3 is required for chromosome condensation in any stage