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Lamassu type I system

traitmech:000573 · CLASS · PROPOSED

A Lamassu system in which an organism possesses a locus encoding the LmuA effector and SMC-like LmuB sensor but no LmuC component.

Trait evidence (4)

  • DOI:10.1073/pnas.2519643122
    We observed loss of LmuC in a specific clade (Clade S, Fig. 1B), an architecture previously called type I Lamassu shown to be antiphage

    Results, effector-diversity paragraph: Haudiquet et al. explicitly identify the LmuC-loss architecture as type I. Clade S occurs in their short-Lamassu phylogeny, but this does not make type I equivalent to the whole short family or establish a universal protein-length cutoff. Clade O's LmuA effector-domain loss is a different observation.

  • DOI:10.1038/s41589-025-02102-z
    the type-I Lamassu complex from Bacillus cellulasensis and the type-II Lamassu complex from Vibrio cholerae

    Abstract: Li et al. independently distinguish the two source-qualified complexes. The associated 9UX7 deposition identifies the type-I source as Bacillus sp. nio-1130, NCBITaxon:1761765. Retain the issuing authority's current label rather than asserting species-name equivalence from the abstract. One studied nuclease mechanism is not a universal mechanism for every type-I effector.

  • https://rest.uniprot.org/uniprotkb/P0DW44.json
    Component of antiviral defense system Lamassu type I, composed of LmuA and LmuB.

    Reviewed P0DW44, entry version 8, retrieved 2026-10-03: the FUNCTION annotation identifies the LmuA/LmuB system in the NIO-1130 source strain (taxon 1761765), citing PMID:29371424. Its protection assays were heterologous expression in B. subtilis BEST7003, not native-host assays. The source organism and expression host are not interchangeable.

  • https://data.rcsb.org/rest/v1/core/polymer_entity/9UX7/1
    "pdbx_gene_src_ncbi_taxonomy_id":"1761765","pdbx_gene_src_scientific_name":"Bacillus sp. nio-1130"

    PDB 9UX7 entity 1 independently records the LmuB source taxon and maps the sequence to P0DW44. The separate expression host is E. coli. The deposited 562-residue length is not a type-I membership threshold; absence of a component from a purified structure alone would not establish genomic absence.

Provenance

Identifier source
TraitMech local identifier
Definition source
DOI:10.1073/pnas.2519643122

Parent traits (1)

Synonyms (1)

  • type I Lamassu EXACT_SYNONYM · DOI:10.1073/pnas.2519643122

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.

  • Bacillus sp. nio-1130 NCBITaxon:1761765 https://rest.uniprot.org/uniprotkb/P0DW44.json NIO-1130 is the source strain of the reviewed LmuB entry P0DW44 explicitly annotated as part of Lamassu type I. PDB 9UX7 entity 1 independently identifies the same source taxon; NCBI confirms this exact current label. The example denotes source-strain possession, not native-host resistance. The cited defense assays used B. subtilis BEST7003 and structural expression used E. coli. The paper's B. cellulasensis name is not asserted as a taxonomic synonym or species-wide trait.

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 type-I architecture and mechanism without inferring absence from missing hits.

KNOWLEDGE GAP OPEN lamassu-type-i-absence-and-mechanism-scope · raised by codex · 2026-10-03

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.

Type I denotes the literature-supported LmuA/LmuB architecture without LmuC, not an isolated LmuB hit, a failed LmuC detector call, an incomplete assembly or a knockout of a type-II locus. Component absence must be established in the biological locus; absence from a purified complex alone is insufficient. The reported clade S is in the short family, but the component definition is not equated with that whole family or a protein length bin. Keep the broad Lamassu parent until wider phylogenetic scope is established; no existing detector-defined effector subtype is reparented from an optional LmuC rule. Type-II loci can coexist in the same genome, so these organism-level possession traits are not asserted disjoint. Source-specific nuclease activity is not generalized to all type-I effectors. A family-wide mechanism, native-host activity and the paper's B. cellulasensis nomenclature relative to current NCBI naming remain unresolved. No causal mechanism graph is asserted.

Curation history

  1. · MINTED_TRAITMECH_ID · codex

    Added the LmuC-lacking Lamassu type-I possession class with two independent primary DOI sources, exact snippets, reviewed UniProt and PDB source metadata, and the NCBI-resolved NIO-1130 example. Ignored-and-hidden searches found no exact record or METPO class. Reserved METPO:1052700 in proposals/metpo_traitmech_v450. Linked existing parent, short-family and type-II discussions without changing their biological definitions or hierarchy.