SKA1

SKA1 (PF3D7_0911200) is a divergent kinetochore component of apicomplexan parasites, identified through interactomics and deep homology searches as one of a set of previously unrecognized kinetochore proteins with a discrete subkinetochore localization (PMID:36006241). In Plasmodium berghei, SKA1 accumulates on the meiotic spindle and kinetochores during zygote development but is undetectable during male microgametogenesis, a stage-specific expression pattern consistent with a meiosis-restricted role in kinetochore–microtubule attachment (PMID:42323312). Beyond its assignment to the kinetochore and its meiotic localization profile, the biochemical function of SKA1 within the kinetochore has not been characterized in the available corpus.

1. 2022 Medium

   Whether apicomplexan parasites possess a definable kinetochore protein inventory was unresolved; identifying SKA1 as a kinetochore component established its membership in the parasite kinetochore machinery.

   Evidence Interactomics (pulldown/co-immunoprecipitation) combined with deep homology searches and subcellular localization imaging in P. falciparum and P. berghei

   PMID:36006241

   Open questions at the time

   • No direct biochemical function or interaction partner of SKA1 within the kinetochore was defined
   • Discrete subkinetochore localization was described but not mechanistically dissected
   • No loss-of-function analysis of SKA1 itself
2. 2026 Medium

   When and where SKA1 acts across the parasite life cycle was unknown; live imaging across gametogenesis and zygote development localized SKA1 to the meiotic spindle and kinetochores while showing its absence from male microgametogenesis, pointing to a meiosis-specific role.

   Evidence Live fluorescence imaging of SKA1-mNG-3xHA with the kinetochore marker NUF2-mScI across life-cycle stages in P. berghei

   PMID:42323312

   Open questions at the time

   • Functional role inferred from stage-specific absence, not from direct loss-of-function of SKA1
   • No demonstration that SKA1 mediates kinetochore–microtubule attachment biochemically
   • Interaction with NUF2 or other kinetochore proteins not directly tested

• The biochemical mechanism by which SKA1 contributes to kinetochore function and the phenotypic consequence of its loss remain unresolved.
• No direct loss-of-function/knockout phenotype for SKA1 reported
• No structural model or defined kinetochore-microtubule binding activity
• Direct interaction partners within the kinetochore not established