identifier: traitmech:000117
label: streptococcus arrangement
definition: A cell arrangement in which dividing cocci remain attached in chains because
  successive division planes are parallel and daughter cells do not fully separate.
definition_source: DOI:10.1128/MMBR.00001-06
trait_category: MORPHOLOGY
term_kind: CLASS
mapping_status: REVIEWED
parent_traits:
- METPO:1000666
synonyms:
- synonym_text: chain-forming cocci
  synonym_type: RELATED_SYNONYM
  source: DOI:10.1128/MMBR.00001-06
evidence:
- reference: DOI:10.1128/MMBR.00001-06
  notes: Young's review of the selective value of bacterial shape treats cell arrangement
    (including chains) as a heritable, division-determined morphology.
- reference: DOI:10.1038/ncomms4842
  notes: Daughter-cell separation during division determines whether cocci stay attached
    in chains versus separating.
canonical_examples:
- taxon_id: NCBITaxon:1314
  taxon_label: Streptococcus pyogenes
  note: "Chains of cocci (streptococcal arrangement) from division in a single plane."
  reference: https://www.ncbi.nlm.nih.gov/books/NBK7611/
causal_graphs:
- graph_id: streptococcus_parallel_division_chain
  title: Streptococcus arrangement via parallel division and incomplete separation
  description: Evidence-backed causal sketch linking parallel division planes and
    incomplete daughter-cell separation to coccal chains.
  nodes:
  - node_id: streptococcus_trait
    label: streptococcus arrangement
    node_type: TRAIT
    grounding: traitmech:000117
    description: Dividing cocci remain attached in chains.
  - node_id: cell_division
    label: cell division
    node_type: BIOLOGICAL_PROCESS
    grounding: GO:0051301
    description: Bacterial binary fission.
  - node_id: parallel_division_planes
    label: parallel division planes
    node_type: QUALITY
    description: Successive division planes oriented in parallel.
  - node_id: daughter_cell_separation
    label: daughter-cell separation
    node_type: BIOLOGICAL_PROCESS
    description: Splitting of the septum so that daughter cells fully separate after
      division.
  - node_id: pg_remodeling
    label: peptidoglycan remodeling
    node_type: BIOLOGICAL_PROCESS
    description: Remodeling and cleavage of septal/peripheral peptidoglycan during
      elongation and division.
  - node_id: pg_hydrolases
    label: peptidoglycan hydrolases
    node_type: GENE_OR_PROTEIN
    description: Septal and peripheral PG hydrolases (e.g. FtsEX-PcsB, CbpD) that
      cleave muropeptides enabling splitting.
  - node_id: pcsb_autolysin
    label: PcsB autolysin
    node_type: GENE_OR_PROTEIN
    description: Essential PG autolysin coordinating PG remodeling with cell division.
  - node_id: ftsex_complex
    label: FtsEX complex
    node_type: GENE_OR_PROTEIN
    description: Membrane complex required for PcsB autolysin function.
  - node_id: lipoteichoic_acid
    label: lipoteichoic acid
    node_type: CHEMICAL
    description: Cell-wall anionic polymer involved in proper cell shape and division.
    grounding: CHEBI:28640
  edges:
  - subject: parallel_division_planes
    predicate: causes
    object: streptococcus_trait
    description: Parallel successive division planes with incomplete daughter separation
      produce coccal chains.
    evidence:
    - reference: DOI:10.1038/ncomms4842
      notes: Daughter-cell separation during division determines whether cocci stay
        attached in chains.
    predicate_id: biolink:causes
  - subject: cell_division
    predicate: enables
    object: streptococcus_trait
    description: Bacterial cell division underlies coccal chain formation.
    evidence:
    - reference: DOI:10.1128/MMBR.00001-06
      notes: Young treats chain arrangement as a heritable, division-determined morphology.
    predicate_id: RO:0002327
  - subject: parallel_division_planes
    predicate: enables
    object: cell_division
    description: Ovococci divide in successive parallel planes perpendicular to the
      long axis.
    evidence:
    - reference: DOI:10.1128/mSphere.00119-21
      notes: Ovococci are elongated ellipsoids divided in successive parallel planes
        perpendicular to their long axis.
    predicate_id: RO:0002327
  - subject: pg_hydrolases
    predicate: enables
    object: pg_remodeling
    description: PG hydrolases release nascent glycan strands and cleave muropeptides,
      enabling PG remodeling and eventual splitting.
    evidence:
    - reference: DOI:10.3389/fmicb.2021.737396
      notes: PG hydrolases are required to release nascent glycan strands and cleave
        muropeptides, enabling integration of new material and eventual splitting.
    predicate_id: RO:0002327
  - subject: pcsb_autolysin
    predicate: promotes
    object: pg_remodeling
    description: PcsB PG remodeling activity is coordinated with cell division.
    evidence:
    - reference: DOI:10.1128/mSphere.00119-21
      notes: The PG remodeling activity by PcsB is coordinated with cell division
        through its interaction with the FtsEX complex.
    predicate_id: RO:0002213
  - subject: ftsex_complex
    predicate: required for
    object: pcsb_autolysin
    description: The FtsEX complex is required for PcsB autolysin function.
    evidence:
    - reference: DOI:10.1128/mSphere.00119-21
      notes: PcsB is the only essential PG autolysin, and the FtsEX complex is required
        for the PcsB function.
  - subject: pg_remodeling
    predicate: promotes
    object: daughter_cell_separation
    description: Septal PG remodeling/splitting enables daughter cells to separate;
      failure maintains chains.
    evidence:
    - reference: DOI:10.1128/mSphere.00119-21
      notes: Part of the residual structure of PG did not fully disintegrate, resulting
        in incomplete cell separation (chain phenotype).
    predicate_id: RO:0002213
  - subject: daughter_cell_separation
    predicate: prevents
    object: streptococcus_trait
    description: Complete daughter-cell separation prevents chain formation; its failure
      produces chains.
    evidence:
    - reference: DOI:10.1038/ncomms4842
      notes: Daughter-cell separation during division determines whether cocci stay
        attached in chains versus separating.
    predicate_id: RO:0002212
  - subject: lipoteichoic_acid
    predicate: promotes
    object: cell_division
    description: Lipoteichoic acid supports proper cell shape and bacterial division.
    evidence:
    - reference: DOI:10.1186/s13567-024-01287-w
      notes: LTA is involved in maintaining proper cell shape and influences cell
        shape and bacterial division.
    predicate_id: RO:0002213
curation_history:
- timestamp: '2026-06-08T00:00:00Z'
  curator: claude
  action: PROPOSED_FROM_RESEARCH
  changes: Proposed candidate MORPHOLOGY trait (streptococcus / chain arrangement);
    leftover round, cell-arrangement sibling of the existing diplococcus shaped.
  llm_assisted: true
- timestamp: '2026-06-09T15:00:00Z'
  curator: claude
  action: CURATED_CAUSAL_GRAPH
  changes: Added evidence-backed causal graph (parallel-plane division → chain) with
    GO node grounding and RO/biolink predicate groundings; promoted PROPOSED to REVIEWED.
  llm_assisted: true
- timestamp: '2026-06-23T00:00:00Z'
  curator: claude
  action: ENRICH_CAUSAL_GRAPH
  changes: Added 7 evidence-backed generic edges (6 new nodes) from the deep-research
    report.
  llm_assisted: true
- timestamp: '2026-06-24T17:21:14Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 6 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002213×3, RO:0002327×2, RO:0002212×1).
  llm_assisted: true
- timestamp: '2026-06-24T17:23:34Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv
    (CHEBI:28640×1).
  llm_assisted: true