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SspABCD-SspE system

traitmech:000222 · CLASS · PROPOSED

A phosphorothioate defense system in which an organism possesses an SspABCD-SspE locus that pairs an SspABCD single-stranded DNA phosphorothioation module with the SspE restriction enzyme to sense host phosphorothioate marks and nick invading DNA.

Trait evidence (6)

  • DOI:10.1038/s41564-020-0700-6
    Here, we describe an unusual SspABCD-SspE PT system in Vibrio cyclitrophicus, Escherichia coli and Streptomyces yokosukanensis

    Xiong et al. name SspABCD-SspE as a bacterial phosphorothioation system distinct from Dnd.

  • DOI:10.1038/s41564-020-0700-6
    SspABCD confers single-stranded and high-frequency PTs with SspB acting as a nickase

    Xiong et al. support the SspABCD modification module and its single-stranded high-frequency PT output.

  • DOI:10.1038/s41564-020-0700-6
    SspABCD coupled with SspE provides protection against phages

    Xiong et al. support the modification-plus-restriction architecture and the antiphage output of SspABCD-SspE.

  • DOI:10.1038/s41467-022-34505-0
    In the PT-based defense system Ssp, SspABCD confers a single-stranded PT modification of host DNA

    Gao et al. support Ssp as a PT-based defense system with host-DNA phosphorothioation by SspABCD.

  • DOI:10.1038/s41467-022-34505-0
    SspE relies on PT modification in host DNA to exert antiphage activity

    Gao et al. connect host PT modification to SspE-mediated antiphage activity.

  • DOI:10.1128/mbio.00933-23
    a novel PT-related R-M system, composed of the modification module SspABCD paired with a single restriction enzyme, SspE

    Jiang et al. support defining this child by the SspABCD modification module paired with single-enzyme SspE restriction, separate from DndFGH and SspFGH systems.

SspABCD-SspE systems couple Ssp PT marks to DNA nicking

Evidence-backed process sketch linking an SspABCD-SspE locus to single-stranded host DNA phosphorothioation, SspE PT-site recognition, SspE GTPase-linked nuclease activation, and reduced phage DNA replication.

NONMECHANISTIC · The graph captures SspABCD-SspE restriction at the system level without asserting one universal host taxon, PT frequency, DNA motif outside 5'-CPSCA-3'-characterized systems, full SspE conformational cycle, or relationship to SspFGH and archaeal PT antiviral systems.

SspABCD-SspE systems couple Ssp PT marks to DNA nicking Interactive directed graph showing evidence-backed causal relationships for SspABCD-SspE system.

Edge evidence

  • SspABCD-SspE locus contributes to Ssp single-stranded DNA phosphorothioation RO:0002326

    The SspABCD modification module installs single-stranded, high-frequency PT marks on host DNA.

    • DOI:10.1038/s41564-020-0700-6 SspABCD confers single-stranded and high-frequency PTs with SspB acting as a nickase Xiong et al. support SspABCD-dependent host DNA phosphorothioation.
  • SspABCD-SspE locus contributes to SspE PT-site recruitment RO:0002326

    SspABCD-SspE loci pair SspABCD host-DNA phosphorothioation with single-enzyme SspE restriction activity.

    • DOI:10.1128/mbio.00933-23 the modification module SspABCD paired with a single restriction enzyme, SspE Jiang et al. support the paired SspABCD modification and SspE restriction architecture.
  • Ssp single-stranded DNA phosphorothioation contributes to SspE PT-site recruitment RO:0002326

    SspE relies on host DNA PT marks and is preferentially recruited to PT sites.

    • DOI:10.1038/s41467-022-34505-0 SspE relies on PT modification in host DNA to exert antiphage activity Gao et al. support PT-dependent SspE activity.
  • SspE PT-site recruitment activates SspE GTPase activation RO:0002213

    PT-site recognition stimulates the SspE GTPase cycle.

    • DOI:10.1038/s41467-022-34505-0 PT recognition enlarges the GTP-binding pocket, thereby increasing GTP hydrolysis activity Gao et al. support PT-induced SspE GTPase activation.
  • SspE GTPase activation activates SspE DNA nicking RO:0002213

    GTPase-linked conformational switching activates SspE nuclease nicking activity.

    • DOI:10.1038/s41467-022-34505-0 turns on the DNA nicking nuclease activity of CTD Gao et al. support activation of SspE DNA-nicking nuclease activity.
  • SspE DNA nicking mitigates phage DNA replication METPO:2007407

    SspE-linked DNA nicking inhibits phage propagation by impairing phage DNA replication.

    • DOI:10.1038/s41564-020-0700-6 SspE inhibits phage propagation by introducing nicking damage to impair phage DNA replication Xiong et al. directly connect SspE DNA-nicking damage to impaired phage DNA replication.
  • SspE DNA nicking confers SspABCD-SspE system METPO:2007700

    SspE DNA nicking realizes the SspABCD-SspE antiphage defense trait.

    • DOI:10.1038/s41467-022-34505-0 enabling SspE to accomplish self-nonself discrimination and limit phage predation Gao et al. support SspE self/nonself discrimination as the Ssp antiphage output.
  • SspABCD-SspE system is a phosphorothioate defense system rdfs:subClassOf

    SspABCD-SspE possession is a phosphorothioate-defense-system trait.

    • DOI:10.1038/s41564-020-0700-6 SspABCD coupled with SspE provides protection against phages Xiong et al. place SspABCD-SspE within phosphorothioation-dependent antiphage defense systems.

Provenance

Identifier source
TraitMech local identifier
Definition source
DOI:10.1038/s41564-020-0700-6

Parent traits (1)

Synonyms (1)

  • SspABCD-SspE PT system EXACT_SYNONYM · DOI:10.1038/s41564-020-0700-6

kg-microbe context

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

Canonical examples (1)

Organisms cited as exemplars of this trait. Taxon ids are NCBITaxon and link out to the NCBI record.

  • Vibrio cyclitrophicus NCBITaxon:47951 DOI:10.1038/s41564-020-0700-6 Xiong et al. describe an SspABCD-SspE PT system in Vibrio cyclitrophicus and analyze its SspABCD-dependent single-stranded PTs plus SspE-dependent antiphage activity.

Curation history

  1. · MINTED_TRAITMECH_ID · codex

    Minted SspABCD-SspE system as a DOI-backed GENOMICS TraitRecord under the phosphorothioate defense system parent 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_v99.