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SPARTA system

traitmech:000240 · CLASS · PROPOSED

A genomics trait describing possession of a short prokaryotic Argonaute TIR-APAZ (SPARTA) locus whose short pAgo and TIR-APAZ proteins form heterodimeric complexes that oligomerize after guide RNA-mediated target DNA binding and unleash TIR domain-mediated NAD(P)ase activity that depletes NAD(P)+ to remove plasmid-invaded cells.

Trait evidence (4)

  • DOI:10.1016/j.cell.2022.03.012
    short prokaryotic Argonaute and the associated TIR-APAZ (SPARTA) proteins form heterodimeric complexes

    Koopal et al. define SPARTA as a short pAgo plus TIR-APAZ system rather than an individual gene or single protein.

  • DOI:10.1016/j.cell.2022.03.012
    Upon guide RNA-mediated target DNA binding, four SPARTA heterodimers form oligomers in which TIR domain-mediated NAD(P)ase activity is unleashed

    Koopal et al. support the guide RNA and target DNA-triggered oligomerization mechanism that activates SPARTA NAD(P)ase activity.

  • DOI:10.1016/j.cell.2022.03.012
    SPARTA is activated in the presence of highly transcribed multicopy plasmid DNA, which causes cell death through NAD(P)+ depletion

    Koopal et al. support plasmid-challenge activation and NAD(P)+ depletion as experimentally demonstrated SPARTA outcomes.

  • DOI:10.1038/s41467-024-49271-4
    cryo-EM structure of the SPARTA oligomer (tetramer of heterodimers) bound to guide-RNA/target-ssDNA

    Kottur et al. independently support the RNA/target-DNA activated oligomeric state of a SPARTA complex.

SPARTA complexes couple guide RNA target binding to NAD(P)ase-triggered cell death

Evidence-backed process sketch linking a SPARTA locus to short-pAgo/TIR-APAZ heterodimer assembly, guide RNA-target DNA activation, oligomerization, TIR-domain NAD(P)ase activity, NAD(P)+ depletion, and removal of plasmid-invaded cells.

NONMECHANISTIC · The graph stays at the SPARTA-family level and models the high-copy plasmid activation route from Koopal et al. without asserting that phage defense, SIR2-APAZ systems, nuclease-APAZ systems, or every other short-pAgo family uses the same enzymatic output.

SPARTA complexes couple guide RNA target binding to NAD(P)ase-triggered cell death Interactive directed graph showing evidence-backed causal relationships for SPARTA system.

Edge evidence

  • SPARTA locus contributes to SPARTA heterodimer assembly RO:0002326

    SPARTA loci encode short pAgo and TIR-APAZ proteins that assemble into heterodimeric complexes.

    • DOI:10.1016/j.cell.2022.03.012 SPARTA proteins form heterodimeric complexes Koopal et al. support the paired-protein complex architecture of SPARTA.
  • SPARTA heterodimer assembly contributes to SPARTA oligomerization RO:0002326

    SPARTA heterodimers are the building blocks of the target-DNA-bound SPARTA oligomer.

  • guide RNA-mediated target DNA binding activates SPARTA oligomerization RO:0002213

    Guide RNA-mediated target DNA binding triggers SPARTA tetramer-of-heterodimers oligomerization.

    • DOI:10.1016/j.cell.2022.03.012 Upon guide RNA-mediated target DNA binding, four SPARTA heterodimers form oligomers Koopal et al. connect target recognition to SPARTA oligomer formation.
  • SPARTA oligomerization activates SPARTA TIR-domain NAD(P)ase activity RO:0002213

    SPARTA oligomerization aligns TIR domains and activates NAD(P)+ hydrolysis.

    • DOI:10.1016/j.cell.2022.03.012 oligomers in which TIR domain-mediated NAD(P)ase activity is unleashed Koopal et al. link oligomer formation to activation of TIR-domain NAD(P)ase activity.
    • DOI:10.1038/s41467-024-49271-4 The TIR domains amass in a parallel-strands arrangement for catalysis Kottur et al. structurally support TIR-domain arrangement in the active SPARTA assembly.
  • SPARTA TIR-domain NAD(P)ase activity contributes to NAD(P)+ depletion RO:0002326

    Activated SPARTA TIR domains hydrolyze NAD(P)+, depleting the cellular NAD(P)+ pool.

    • DOI:10.1038/s41467-024-49271-4 activated by invading DNA to unleash its TIR domain for NAD(P)+ hydrolysis Kottur et al. describe DNA-triggered release of SPARTA TIR-domain NAD(P)+ hydrolysis.
  • NAD(P)+ depletion contributes to plasmid-invaded cell death RO:0002326

    SPARTA-associated NAD(P)+ depletion contributes to death of plasmid-invaded host cells.

  • plasmid-invaded cell death confers SPARTA system METPO:2007700

    Removal of plasmid-invaded cells is the cellular outcome of the SPARTA possession trait.

    • DOI:10.1016/j.cell.2022.03.012 This results in the removal of plasmid-invaded cells from bacterial cultures Koopal et al. support SPARTA-mediated removal of plasmid-invaded cells.

Provenance

Identifier source
TraitMech local identifier
Definition source
DOI:10.1016/j.cell.2022.03.012

Parent traits (1)

Synonyms (1)

  • short prokaryotic Argonaute TIR-APAZ system EXACT_SYNONYM · DOI:10.1016/j.cell.2022.03.012

kg-microbe context

No kg-microbe node embedding matched this record in the 2026-04-25 deepwalk.

Discussions and Knowledge Gaps (1)

Open questions attached to this trait. Seeded by just knowledge-gap-scan and curated; see the corpus-wide index.

Resolve SPARTA natural-host substrates before adding canonical examples or narrower short-pAgo defense children.

KNOWLEDGE GAP OPEN sparta-native-host-and-substrate-gap · raised by codex · 2026-09-18

Not yet attached to a section of this record — a curator sets attaches_to (e.g. causal_graphs#some_edge) so the gap shows beside the mechanism it concerns.

Koopal et al. support strong high-copy plasmid activation and only limited, NADase-independent phage effects; Kottur et al. support C. thermophila SPARTA structural activation. This first record therefore stays broad until natural-host activity, phage scope, and whether SIR2-APAZ or nuclease-APAZ relatives should be separate children are resolved.

Curation history

  1. · MINTED_TRAITMECH_ID · codex

    Minted SPARTA system as a DOI-backed GENOMICS TraitRecord under the quality root after an ignored-and-hidden duplicate review found no exact live TraitMech, METPO, or prior proposal record; the replacement placeholder is reserved in proposals/metpo_traitmech_v117.

  2. · REPAIRED_PARENT_TRAIT · codex

    Reparented SPARTA system from the generic quality root to the newly minted prokaryotic Argonaute defense system parent without changing SPARTA-specific evidence or mechanism claims.