identifier: METPO:1000683
label: sphere shaped
definition: A cell shape in which an organism has a spherical or nearly spherical
  morphology with roughly equal dimensions in all directions.
definition_source: DOI:10.1038/nrmicro3088
trait_category: MORPHOLOGY
term_kind: CLASS
mapping_status: REVIEWED
parent_traits:
- METPO:1000666
synonyms:
- synonym_text: S_sphere
  synonym_type: RELATED_SYNONYM
  source: metpo.owl
- synonym_text: sphere-shaped
  synonym_type: RELATED_SYNONYM
  source: metpo.owl
created_by: Anthea Guo
evidence:
- reference: DOI:10.1038/nrmicro3088
  snippet: spherical cocci synthesize peptidoglycan only at the division septum
  notes: Supports spherical bacterial morphology as associated with septal peptidoglycan
    synthesis.
canonical_examples:
- taxon_id: NCBITaxon:1280
  taxon_label: Staphylococcus aureus
  note: "spherical coccus"
  reference: PMID:40704795
- taxon_id: NCBITaxon:1313
  taxon_label: Streptococcus pneumoniae
  note: "near-spherical diplococcus"
  reference: PMID:31172911
causal_graphs:
- graph_id: sphere_shaped_septal_peptidoglycan
  title: Spherical shape septal peptidoglycan mechanism
  description: Evidence-backed causal sketch linking spherical cell shape to FtsZ-associated
    septal synthesis, peptidoglycan remodeling, and limited lateral elongation.
  nodes:
  - node_id: sphere_shaped_trait
    label: sphere shaped
    node_type: TRAIT
    grounding: METPO:1000683
    description: Spherical bacterial cell morphology.
  - node_id: ftsZ_division_ring
    label: FtsZ division ring
    node_type: GENE_OR_PROTEIN
    description: Tubulin-like division scaffold.
  - node_id: septal_peptidoglycan_synthesis
    label: septal peptidoglycan synthesis
    node_type: BIOLOGICAL_PROCESS
    description: Cell-wall synthesis localized to the division septum.
  - node_id: peptidoglycan_cell_wall
    label: peptidoglycan cell wall
    node_type: CELLULAR_LOCALIZATION
    grounding: GO:0009274
    description: Cell-wall polymer network maintaining bacterial shape.
  - node_id: lateral_elongation
    label: lateral cell-wall elongation
    node_type: BIOLOGICAL_PROCESS
    description: Sidewall growth mode that lengthens rods.
  - node_id: mreB_elongation_machinery
    label: MreB-mediated elongation machinery
    node_type: GENE_OR_PROTEIN
    description: Actin-like MreB cytoskeleton directing lateral (rod) elongation.
  - node_id: elongation_capacity
    label: elongation capacity
    node_type: CAPACITY
    description: Capacity of a cell to elongate into a rod via sidewall growth.
  - node_id: divisome_pbps
    label: divisome and PBPs
    node_type: GENE_OR_PROTEIN
    description: Division machinery and penicillin-binding proteins recruited to mid-cell.
  - node_id: ftsZ_treadmilling
    label: FtsZ treadmilling
    node_type: BIOLOGICAL_PROCESS
    description: Treadmilling of FtsZ polymers distributing PG synthases around the
      Z-ring.
  - node_id: ftsW_flippase
    label: FtsW lipid II flippase
    node_type: GENE_OR_PROTEIN
    description: Septally localized flippase that translocates lipid II across the
      membrane.
  - node_id: lipid_ii
    label: lipid II
    node_type: CHEMICAL
    description: Membrane-bound peptidoglycan precursor and PBP substrate.
    grounding: CHEBI:27692
  edges:
  - subject: ftsZ_division_ring
    predicate: enables
    object: septal_peptidoglycan_synthesis
    description: The FtsZ division ring organizes septal wall synthesis.
    evidence:
    - reference: DOI:10.1038/nrmicro1205
      snippet: FtsZ collaborates with penicillin binding proteins
      notes: Supports FtsZ-PBP cooperation in division-associated shape generation.
    predicate_id: RO:0002327
  - subject: septal_peptidoglycan_synthesis
    predicate: builds
    object: peptidoglycan_cell_wall
    description: Septal synthesis builds and remodels the spherical cell wall.
    evidence:
    - reference: DOI:10.1038/nrmicro3088
      snippet: synthesize peptidoglycan only at the division septum
      notes: Supports septal-only PG synthesis in spherical cocci.
    predicate_id: biolink:produces
  - subject: lateral_elongation
    predicate: reduced in
    object: sphere_shaped_trait
    description: Reduced lateral elongation helps preserve a sphere rather than a
      rod.
    evidence:
    - reference: DOI:10.1038/nrmicro3088
      snippet: mechanisms controlling growth and division of coccoid bacteria
      notes: Broad review supports different growth mechanisms for coccoid versus
        rod-shaped bacteria.
  - subject: peptidoglycan_cell_wall
    predicate: regulates
    object: sphere_shaped_trait
    description: Peptidoglycan wall geometry maintains the spherical shape.
    evidence:
    - reference: DOI:10.1038/nrmicro1205
      snippet: primary role in maintaining cell shape
      notes: Supports the cell wall as central to bacterial shape maintenance.
    predicate_id: RO:0002211
  - subject: septal_peptidoglycan_synthesis
    predicate: contributes to
    object: sphere_shaped_trait
    description: Septal-only peptidoglycan synthesis in cocci produces spherical morphology.
    evidence:
    - reference: DOI:10.1038/nrmicro3088
      notes: spherical cocci synthesize peptidoglycan only at the division septum
    predicate_id: RO:0002326
  - subject: mreB_elongation_machinery
    predicate: causally upstream of
    object: elongation_capacity
    description: Loss of the MreB cytoskeleton removes the elongation capacity that
      lengthens rods.
    evidence:
    - reference: DOI:10.1038/nrmicro3088
      notes: loss of the MreB cytoskeleton is the main factor that prevents cocci
        from elongating into rods
  - subject: elongation_capacity
    predicate: reduced in
    object: sphere_shaped_trait
    description: Loss of elongation capacity prevents cocci from elongating into rods,
      favoring a sphere.
    evidence:
    - reference: DOI:10.1038/nrmicro3088
      notes: prevents cocci from elongating into rods
  - subject: ftsZ_division_ring
    predicate: recruits
    object: divisome_pbps
    description: FtsZ assembly into a mid-cell Z ring recruits PBPs and divisome components.
    evidence:
    - reference: DOI:10.1038/nrmicro3088
      notes: cell division is initiated by FtsZ assembly into a mid-cell Z ring that
        recruits PBPs and divisome components
  - subject: ftsZ_treadmilling
    predicate: regulates
    object: septal_peptidoglycan_synthesis
    description: FtsZ treadmilling distributes the PG synthases that form the septum.
    evidence:
    - reference: DOI:10.1042/bsr20221664
      notes: The FtsZ polymers undergo treadmilling around the Z-ring to distribute
        the PG synthases forming the septum
    predicate_id: RO:0002211
  - subject: ftsW_flippase
    predicate: enables
    object: lipid_ii
    description: FtsW flips lipid II to the outer septal face for PG synthesis.
    evidence:
    - reference: DOI:10.1038/nrmicro3088
      notes: lipid II is flipped to the outside by the septally localized flippase
        FtsW
    predicate_id: RO:0002327
  - subject: lipid_ii
    predicate: enables
    object: septal_peptidoglycan_synthesis
    description: Lipid II serves as the PBP substrate for septal peptidoglycan synthesis.
    evidence:
    - reference: DOI:10.1038/nrmicro3088
      notes: PG synthesis uses lipid II as the PBP substrate
    predicate_id: RO:0002327
curation_history:
- timestamp: '2026-05-05T01:35:46.894456+00:00'
  curator: seed_from_metpo
  action: SEEDED_FROM_METPO
  changes: imported from data/raw/metpo.owl (CLASS)
  llm_assisted: false
- timestamp: '2026-05-11T20:05:00-07:00'
  curator: codex
  action: CURATED_WITH_LITERATURE
  changes: Added DOI-backed definition and causal graph for FtsZ-associated septal
    peptidoglycan synthesis, peptidoglycan cell wall, reduced lateral elongation,
    and spherical morphology.
  llm_assisted: true
- timestamp: '2026-05-24T04:13:19Z'
  curator: claude
  action: RENAME_PREDICATE_LABELS
  changes: 'Renamed 1 causal-edge predicate label(s) to align with existing groundings:
    maintains → regulates ×1.'
  llm_assisted: true
- timestamp: '2026-05-24T04:13:22Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002211×1).
  llm_assisted: true
- timestamp: '2026-05-26T05:00:48Z'
  curator: claude
  action: RENAME_PREDICATE_LABELS
  changes: 'Renamed 1 causal-edge predicate label(s) to align with existing groundings:
    organizes → enables ×1.'
  llm_assisted: true
- timestamp: '2026-05-26T05:00:51Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002327×1).
  llm_assisted: true
- timestamp: '2026-06-13T21:03:26Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (biolink:produces×1).
  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 4 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002327×2, RO:0002326×1, RO:0002211×1).
  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:27692×1).
  llm_assisted: true