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SspABCD-SspFGH system

traitmech:000223 · CLASS · PROPOSED

A phosphorothioate defense system in which an organism possesses an SspABCD-SspFGH locus that pairs an SspABCD-family single-stranded DNA phosphorothioation module with an SspFGH restriction module to damage non-phosphorothioated phage DNA and suppress phage DNA replication.

Trait evidence (6)

  • DOI:10.1128/mbio.00613-21
    new type of ssDNA PT-based SspABCD-SspFGH defense system capable of providing protection against phages

    Wang et al. name SspABCD-SspFGH as a single-stranded DNA phosphorothioation-based bacterial phage-defense system.

  • DOI:10.1128/mbio.00613-21
    PT-modifying genes sspBCD and iscS in Vibrio anguillarum strain FF-93 can provide protection against a range of phages in combination with sspFGH

    Wang et al. support a native Vibrio anguillarum FF-93 Ssp system whose IscS-SspBCD phosphorothioation module works with the sspFGH cassette.

  • DOI:10.1128/mbio.00613-21
    SspFGH coupled with IscS-SspBCD behaves as a new type of ssDNA PT modification-based defense barrier to fend off phage invasion

    Wang et al. support the modification-plus-restriction architecture and antiphage output.

  • DOI:10.1128/mbio.00613-21
    SspFGH damages non-PT-modified DNA and exerts antiphage activity by suppressing phage DNA replication

    Wang et al. connect SspFGH-dependent DNA damage to the observed block in phage DNA replication.

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

    Xiong et al. independently support SspABCD-family single-stranded host-DNA phosphorothioation.

  • DOI:10.3390/ijms252413316
    could also be coupled to SspFGH for anti-phage activity

    Xu and Gu summarize SspFGH as an SspABCD-coupled phosphorothioate antiphage restriction module.

SspABCD-SspFGH systems couple Ssp PT marks to foreign-DNA damage

Evidence-backed process sketch linking an SspABCD-SspFGH locus to single-stranded host DNA phosphorothioation, SspFGH-dependent damage of non-phosphorothioated phage DNA, and reduced phage DNA replication.

NONMECHANISTIC · The graph captures SspABCD-SspFGH restriction at the system level without asserting one universal host taxon, PT frequency, a DNA-damage chemistry, a complete SspFGH subunit cycle, or relationship to SspE and archaeal PT antiviral systems.

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

Edge evidence

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

    The SspABCD-family modification module installs single-stranded PT marks on host DNA.

    • DOI:10.1128/mbio.00613-21 IscS and SspBCD in FF-93 also confer DNA PT modification at 5'-CPSCA-3' consensus sequences Wang et al. support single-stranded host-DNA phosphorothioation by the FF-93 IscS-SspBCD module.
  • SspABCD-SspFGH locus contributes to SspFGH-dependent non-PT DNA damage RO:0002326

    SspABCD-SspFGH loci pair the Ssp modification module with SspFGH-dependent restriction activity against DNA lacking PT marks.

    • DOI:10.1128/mbio.00613-21 SspFGH coupled with IscS-SspBCD behaves as a new type of ssDNA PT modification-based defense barrier Wang et al. support the paired Ssp phosphorothioation and SspFGH restriction architecture.
  • Ssp single-stranded DNA phosphorothioation contributes to Ssp PT self/nonself discrimination RO:0002326

    SspFGH uses Ssp phosphorothioate marks as a recognition tag to discriminate self DNA from invading non-PT DNA.

    • DOI:10.1128/mbio.00613-21 SspFGH employs ssDNA PT modification as a recognition tag to introduce damage to non-PT-modified phage genomes Wang et al. support PT-dependent self/nonself discrimination by the SspFGH barrier.
  • Ssp PT self/nonself discrimination activates SspFGH-dependent non-PT DNA damage RO:0002213

    Ssp PT self/nonself discrimination leads to SspFGH-dependent damage of non-PT phage DNA.

    • DOI:10.1128/mbio.00613-21 SspFGH introduces damage to non-PT DNA and consequently impairs phage DNA replication Wang et al. connect SspFGH non-PT DNA damage to the restriction output.
  • SspFGH-dependent non-PT DNA damage mitigates phage DNA replication METPO:2007407

    SspFGH-dependent damage of phage DNA suppresses phage DNA replication.

    • DOI:10.1128/mbio.00613-21 its DNA replication was markedly suppressed in the presence of IscS-SspBCD-SspFGH Wang et al. directly connect the SspFGH barrier to impaired phage DNA replication.
  • SspFGH-dependent non-PT DNA damage confers SspABCD-SspFGH system METPO:2007700

    SspFGH-dependent non-PT DNA damage realizes the SspABCD-SspFGH antiphage defense trait.

    • DOI:10.1128/mbio.00613-21 SspFGH provided moderate levels of protection against phages Wang et al. support phage restriction as the SspFGH system output.
  • SspABCD-SspFGH system is a phosphorothioate defense system rdfs:subClassOf

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

    • DOI:10.1128/mbio.00613-21 new type of ssDNA PT-based SspABCD-SspFGH defense system Wang et al. place SspABCD-SspFGH among single-stranded DNA phosphorothioation-based defense systems.

Provenance

Identifier source
TraitMech local identifier
Definition source
DOI:10.1128/mbio.00613-21

Parent traits (1)

Synonyms (1)

  • SspABCD-SspFGH defense system EXACT_SYNONYM · DOI:10.1128/mbio.00613-21

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 anguillarum NCBITaxon:55601 DOI:10.1128/mbio.00613-21 Wang et al. identified an sspFGH cassette adjacent to the sspBCD cluster in Vibrio anguillarum FF-93 and showed that its SspFGH module couples to IscS-SspBCD phosphorothioation for phage defense.

Curation history

  1. · MINTED_TRAITMECH_ID · codex

    Minted SspABCD-SspFGH 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_v100.