Affinage · Toxoplasma gondii

IMC29

inner membrane complex protein IMC29 · UniProt A0A125YT41

Annotated
2026-09-10
2 papers in source corpus 1 papers cited in narrative 3 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

IMC29 is an early daughter-bud component of the inner membrane complex (IMC) in Toxoplasma gondii that is required for faithful endodyogeny; its deletion causes severe replication and growth defects and complete loss of virulence, establishing it as a critical scaffold of the nascent daughter IMC (PMID:36622147). Localization to the daughter IMC is governed by the N-terminal half of the protein, which contains four predicted coiled-coil domains, whereas a short C-terminal helical region is dispensable for targeting but required for IMC29 function (PMID:36622147). Used as a proximity-labeling bait, IMC29 marks the daughter-bud IMC neighborhood and captured eight novel daughter-enriched IMC proteins plus four proteins with distinct localizations at the parasite-parasite interface or the outer IMC face, expanding the daughter IMC proteome (PMID:36622147). Beyond this scaffolding and interactome role, no enzymatic activity or direct binding partner of IMC29 has been characterized in the available corpus.

Mechanistic history

Synthesis pass · year-by-year structured walk · 3 steps
  1. 2023 High

    It was unknown which components drive early daughter IMC formation; deletion of IMC29 showed it is required for faithful endodyogeny, establishing a specific early daughter-bud factor whose loss cripples replication and virulence.

    Evidence Gene deletion (Δimc29) with replication, growth, and in vivo virulence readouts in T. gondii

    PMID:36622147

    Open questions at the time
    • Molecular mechanism linking IMC29 loss to replication failure not defined
    • No enzymatic activity or biochemical function assigned
    • Direct binding partners not identified
  2. 2023 Medium

    To separate targeting from function, domain-deletion analysis mapped daughter-IMC localization to the N-terminal coiled-coil region and functional requirement to a short C-terminal helix, distinguishing the structural elements that recruit IMC29 from those needed for its activity.

    Evidence Deletion/domain-mapping analysis with localization and functional assays in T. gondii

    PMID:36622147

    Open questions at the time
    • Binding partners of the coiled-coil region not identified
    • Molecular function of the C-terminal helix unresolved
    • No structural model of the domains
  3. 2023 Medium

    To place IMC29 in its molecular neighborhood, proximity labeling with IMC29 as bait expanded the daughter IMC proteome, identifying novel daughter-enriched and interface/outer-IMC proteins and defining the compartment IMC29 helps organize.

    Evidence BioID with IMC29 as bait plus mass spectrometry and direct localization validation in T. gondii

    PMID:36622147

    Open questions at the time
    • Which proximity hits are direct binding partners versus neighborhood proteins is unresolved
    • Functional roles of the newly identified proteins not established
    • No reciprocal validation of individual interactions

Mechanism profile

Synthesis pass · controlled-vocabulary classification
No controlled-vocabulary terms were assigned to this entry.

Evidence

Reading pass · 3 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2023 IMC29 localizes specifically to the daughter bud IMC and plays an important role in parasite replication; Δimc29 parasites exhibit severe replication defects, substantial growth defects, and loss of virulence, establishing IMC29 as an early daughter bud component required for faithful endodyogeny. Gene deletion (Δimc29) with phenotypic readouts of replication, growth, and in vivo virulence mBio High 36622147
2023 IMC29 localization to the daughter IMC is largely dependent on the N-terminal half of the protein containing four predicted coiled-coil domains, while IMC29 function requires a short C-terminal helical region, as determined by deletion analyses. Deletion analysis / domain-mapping by localization and functional assays mBio Medium 36622147
2023 Proximity labeling using IMC29 as bait identified eight novel IMC proteins enriched in daughter buds and four novel proteins with unique localizations to the interface between two parasites or to the outer face of the IMC, expanding the daughter IMC proteome. Proximity-dependent biotin identification (BioID) / proximity labeling with IMC29 as bait, followed by mass spectrometry and localization studies mBio Medium 36622147

Source papers

Stage 0 corpus · 2 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2016 Novel insights into the composition and function of the Toxoplasma IMC sutures. Cellular microbiology 59 27696623
2023 IMC29 Plays an Important Role in Toxoplasma Endodyogeny and Reveals New Components of the Daughter-Enriched IMC Proteome. mBio 30 36622147