NUF2

NUF2 (PF3D7_0316500) is an outer kinetochore protein that functions as a subunit of the NDC80 complex, coordinating chromosome segregation during the unusual nuclear divisions of Plasmodium across multiple life-cycle stages (PMID:38987258, PMID:32501284). In P. berghei, NUF2 forms a heterodimer with NDC80, and this NDC80–NUF2 dimer mediates microtubule plus-end binding through calponin homology domains (PMID:32501284); NUF2-3xHA immunoprecipitation followed by mass spectrometry recovered partners consistent with NDC80 complex membership (PMID:36006241). NUF2 localises to nuclear-peripheral kinetochore puncta in a cell-cycle-dependent manner—absent in G1/ring stages, first appearing at the onset of DNA replication, accumulating as punctate foci during chromosome segregation, and becoming undetectable in fully budded schizonts—and it marks kinetochore structures dynamically during mosquito stages (PMID:36006241). In P. falciparum, conditional disruption of NUF2 causes aberrant mitotic spindle organisation, disruption of the centromere marker CENH3, and impaired karyokinesis; unexpectedly, it also disengages the centriolar plaque from the nuclear envelope, uncoupling the nucleus from the apical complex and producing anucleate merozoites, revealing a role for the kinetochore/spindle machinery in positioning the nascent apical complex (PMID:38987258). NUF2 further co-localises with Aurora-related kinase ARK1 at spindle-pole MTOCs and along spindle microtubules and kinetochores during male gametogenesis, and was recovered as an ARK2-associated kinetochore protein by crosslink immunoprecipitation, placing it in a kinetochore compartment that interacts with Aurora-related kinase complexes during chromosome segregation (PMID:42323312).

1. 2020 Medium

   Establishing NUF2 as a component of the Plasmodium outer kinetochore addressed whether this apicomplexan parasite possesses a canonical NDC80-based microtubule-attachment module, defining the molecular identity of the protein.

   Evidence Live-cell imaging of GFP-tagged NDC80 complex components and deep homology searches in P. berghei, with spatiotemporal tracking across life-cycle stages

   PMID:32501284

   Open questions at the time

   • No in vitro reconstitution of the Plasmodium-specific NDC80–NUF2 dimer
   • Direct microtubule-binding activity of NUF2 itself not biochemically isolated from the dimer
   • Single lab, homology-based subunit assignment
2. 2022 Medium

   Defining the cell-cycle-dependent localisation of NUF2 and its interaction partners clarified when and where the protein acts during the atypical closed mitoses of Plasmodium and confirmed its NDC80 complex membership by proteomics.

   Evidence Live-cell fluorescence of endogenously tagged NUF2-mScarlet-I, U-ExM co-localisation with spindle/pole markers, and reciprocal IP-MS of NUF2-3xHA in P. berghei

   PMID:36006241

   Open questions at the time

   • Functional consequence of NUF2 loss not tested in this study
   • Interaction partner list not resolved to direct versus indirect contacts
   • Single-lab dataset
3. 2024 High

   Conditional loss-of-function established what NUF2 is required for in vivo and revealed an unanticipated role beyond chromosome segregation in coupling the nucleus to the developing apical complex.

   Evidence Conditional genetic disruption combined with U-ExM using spindle, CENH3 centromere, and centriolar plaque markers in P. falciparum

   PMID:38987258

   Open questions at the time

   • Molecular mechanism by which NUF2/kinetochore loss disengages the centriolar plaque from the nuclear envelope is unresolved
   • Whether the anucleate-merozoite phenotype is a direct NUF2 function or an indirect consequence of segregation failure not distinguished
   • No structural basis for the observed defects
4. 2026 Medium

   Placing NUF2 in a kinetochore compartment that associates with Aurora-related kinases during male gametogenesis began to connect kinetochore attachment to regulatory kinase signalling in sexual-stage division.

   Evidence U-ExM co-localisation of NUF2 with ARK1 and reciprocal crosslink IP-MS recovering NUF2 as an ARK2-associated kinetochore protein in P. berghei

   PMID:42323312

   Open questions at the time

   • NUF2-specific functional data are limited in this study
   • Whether NUF2 is a direct binding partner or substrate of ARK1/ARK2 is not established
   • Single study

• How NUF2 mechanistically links kinetochore/spindle integrity to centriolar plaque anchoring at the nuclear envelope, and whether this coupling is regulated by Aurora-related kinases, remains unresolved.
• No structural or reconstitution data for the Plasmodium NDC80–NUF2 dimer
• Mechanistic connection between kinetochore function and apical-complex positioning uncharacterized
• Regulatory inputs from Aurora-related kinases onto NUF2 not defined