Affinage · Plasmodium

EB1

PF3D7_0307300 · end-binding protein 1

Annotated
2026-09-07
6 papers in source corpus 4 papers cited in narrative 7 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

EB1 (PF3D7_0307300) is a divergent Plasmodium end-binding protein that governs spindle-based nuclear division during male gametogenesis (PMID:37208365). Unlike canonical eukaryotic EB1, it does not track microtubule plus-ends; instead it binds along the full microtubule lattice through contributions from both its CH domain and linker region (PMID:37208365). In P. falciparum male gametocytes it resides in the nucleoplasm and decorates the entire length of spindle microtubules during endomitosis, where it shapes spindle structure and enables lateral kinetochore–spindle attachment (PMID:37208365). Consistent with this role, EB1 deletion yields male gametocytes that produce anucleated microgametes owing to failed nuclear segregation/partitioning, defining an essential, male-specific fertility function that leaves asexual proliferation and gametocytogenesis intact (PMID:37535401, PMID:37208365). EB1 is recruited to a nuclear-membrane-embedded MTOC and participates in nuclear microtubule assembly/disassembly driving nuclear elongation and chromatin organization (PMID:36030238). In P. berghei sexual stages, EB1 physically associates with the aurora-related kinase ARK2 at spindle microtubules near kinetochores, and the two proteins play complementary, non-redundant roles in endomitotic division and mosquito transmission (PMID:37704606). Upstream, EB1 is hypophosphorylated in CDPK4-null gametocytes, placing it downstream of CDPK4-dependent signaling (PMID:37535401).

Mechanistic history

Synthesis pass · year-by-year structured walk · 6 steps
  1. 2022 Medium

    Before its molecular role was defined, it was unknown how mitotic machinery organized the unusual nuclear division of Plasmodium gametocytes; this established EB1 as a component recruited to a nuclear-membrane MTOC driving nuclear microtubule dynamics.

    Evidence 3D electron microscopy, fluorescence microscopy and trifluralin microtubule depolymerization in P. falciparum gametocytes

    PMID:36030238

    Open questions at the time
    • Does not resolve which microtubule-binding mode EB1 uses
    • Does not distinguish EB1's contribution from other MTOC components
  2. 2023 High

    It was unknown whether Plasmodium EB1 behaves like canonical plus-end-tracking EB1; in vitro reconstitution with domain dissection showed it instead binds the full microtubule lattice via its CH domain and linker, redefining it as a divergent orthologue.

    Evidence In vitro microtubule binding assays, in vivo live-cell imaging and domain mutagenesis in P. falciparum

    PMID:37208365

    Open questions at the time
    • Structural basis of lattice binding not resolved
    • Functional consequence of removing individual binding determinants in vivo not fully mapped
  3. 2023 High

    Whether EB1's lattice binding served a specific division function was open; localization and knockout imaging established that EB1 coats spindle microtubules and is required for lateral kinetochore–spindle attachment during endomitosis.

    Evidence Live-cell and fixed fluorescence microscopy in EB1-deficient P. falciparum lines

    PMID:37208365

    Open questions at the time
    • Molecular link between lattice binding and kinetochore attachment not defined
    • Does not identify the kinetochore-side partner
  4. 2023 High

    The biological importance of EB1 was unresolved; gene deletion demonstrated an essential, stage-specific role, as EB1-null males form anucleated gametes while asexual growth and gametocytogenesis are unaffected.

    Evidence Gene deletion, genetic crosses with male/female-sterile lines and microscopy in P. falciparum NF54, corroborated by two labs

    PMID:37208365 PMID:37535401

    Open questions at the time
    • Mechanism linking segregation failure to anucleate gametes not fully dissected
    • Female-side contribution not characterized
  5. 2023 Medium

    How EB1 is coordinated with mitotic kinases was unknown; interactomics and genetics in P. berghei placed EB1 as a physical partner of ARK2 at spindle microtubules with complementary, non-redundant roles in division and transmission.

    Evidence Mass spectrometry interactomics, super-resolution/live-cell imaging and gene deletion with mosquito transmission assays in P. berghei

    PMID:37704606

    Open questions at the time
    • Direct binding interface between EB1 and ARK2 not mapped
    • Whether ARK2 regulates EB1 activity or vice versa is unresolved
    • Shown in P. berghei; direct interaction not verified in P. falciparum
  6. 2023 Low

    The upstream regulatory input to EB1 was unknown; comparative phosphoproteomics showed EB1 is hypophosphorylated in CDPK4-null gametocytes, placing it downstream of CDPK4 signaling.

    Evidence Comparative phospho-proteome analysis of Pfcdpk4 knockout gametocytes

    PMID:37535401

    Open questions at the time
    • Single phosphoproteomics dataset without functional validation of the phosphosite on EB1
    • Whether phosphorylation is direct or indirect not established
    • Functional effect of the modification on EB1 activity unknown

Open questions

Synthesis pass · forward-looking unresolved questions
  • How EB1's lattice-binding activity mechanistically drives lateral kinetochore–spindle attachment, and how CDPK4 phosphorylation and ARK2 association converge to control this during male gametogenesis, remain unresolved.
  • No structural model of EB1 on the lattice or at kinetochores
  • Causal chain from CDPK4 phosphorylation to EB1 function not established
  • EB1–ARK2 interaction interface and regulatory hierarchy undefined

Mechanism profile

Synthesis pass · controlled-vocabulary classification
Partners
ARK2 (AURORA-RELATED KINASE; PHYSICAL INTERACTOR IN P. BERGHEI SEXUAL STAGES) [#3]CDPK4 (CA2+-DEPENDENT PROTEIN KINASE 4; UPSTREAM REGULATOR, EB1 HYPOPHOSPHORYLATED IN CDPK4-NULL GAMETOCYTES) [#6]

Evidence

Reading pass · 7 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2023 Plasmodium EB1 is an orthologue distinct from canonical eukaryotic EB1: in vitro and in vivo assays demonstrate it lacks microtubule plus-end tracking but possesses microtubule-lattice binding affinity, contributed by both its CH domain and linker region. In vitro microtubule binding assays and in vivo live-cell imaging; domain mutagenesis/analysis Nature communications High 37208365
2023 EB1 localizes to the nucleoplasm of male gametocytes and, during gametogenesis, decorates the full length of spindle microtubules (not just plus-ends), regulating spindle structure and enabling lateral kinetochore-spindle attachment throughout endomitosis in an EB1-dependent manner. Fluorescence microscopy (live-cell and fixed), EB1-deficient parasite lines Nature communications High 37208365
2023 Deletion of EB1 in P. falciparum produces male gametocytes that develop into anucleated male gametes (severe defect in nuclear segregation/partitioning into emerging microgametes), revealing an essential male-specific fertility function; asexual proliferation and gametocytogenesis are unaffected. Gene deletion (KO), genetic crosses with male- and female-sterile parasite lines, microscopy mBio High 37208365 37535401
2023 EB1 is identified as a physical interactor of the aurora-related kinase ARK2 in Plasmodium berghei sexual stages; interactomic (mass spectrometry) and co-localization studies place EB1 at spindle microtubules in the vicinity of kinetochores during both mitosis and meiosis. Mass spectrometry-based interactomics (co-immunoprecipitation/pulldown), super-resolution and live-cell fluorescence microscopy Nature communications Medium 37704606
2023 Gene function studies show that ARK2 and EB1 have complementary (non-redundant) roles in driving endomitotic division and parasite transmission through the mosquito in P. berghei sexual stages. Genetic epistasis / gene deletion of ARK2 and EB1, mosquito transmission assays Nature communications Medium 37704606
2022 In P. falciparum gametocytes, EB1 (end-binding protein-1) is a component of classical mitotic machinery recruited to a non-mitotic MTOC embedded in the nuclear membrane, where it participates in nuclear microtubule assembly/disassembly processes that drive nuclear elongation and chromatin organization during gametocyte development. 3D electron microscopy, fluorescence microscopy, microtubule depolymerization (trifluralin treatment) Nature communications Medium 36030238
2023 PfEB1 is hypophosphorylated in Pfcdpk4-deleted gametocytes, placing it downstream of Ca2+-dependent protein kinase 4 (CDPK4) in a signaling pathway regulating microtubule dynamics during male gametogenesis. Comparative phospho-proteome analysis of Pfcdpk4 knockout gametocytes mBio Low 37535401

Source papers

Stage 0 corpus · 6 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2022 Repurposing the mitotic machinery to drive cellular elongation and chromatin reorganisation in Plasmodium falciparum gametocytes. Nature communications 32 36030238
2023 Plasmodium ARK2 and EB1 drive unconventional spindle dynamics, during chromosome segregation in sexual transmission stages. Nature communications 29 37704606
2023 EB1 decoration of microtubule lattice facilitates spindle-kinetochore lateral attachment in Plasmodium male gametogenesis. Nature communications 16 37208365
2023 Plasmodium microtubule-binding protein EB1 is critical for partitioning of nuclei in male gametogenesis. mBio 5 37535401
2023 Plasmodium ARK2-EB1 axis drives the unconventional spindle dynamics, scaffold formation and chromosome segregation of sexual transmission stages. Research square 2 36798191
2023 Plasmodium ARK2-EB1 axis drives the unconventional spindle dynamics, scaffold formation and chromosome segregation of sexual transmission stages. bioRxiv : the preprint server for biology 1 36778504