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irregular shaped

METPO:1000691 · CLASS · REVIEWED

A cell shape lacking a consistent geometric form across individual cells of a population.

Irregular-shape loss of wall patterning

DOI-backed graph linking reduced or stochastic cell-wall patterning to inconsistent, irregular cell geometry.

Irregular-shape loss of wall patterning Interactive directed graph showing evidence-backed causal relationships for irregular shaped.

Edge evidence

  • reduced cell-wall patterning enables stochastic growth RO:0002327

    Reduced patterning permits stochastic growth-zone placement.

    • DOI:10.1146/annurev-cellbio-101011-155745 cell shape is genetically determined Supports patterning loss as a driver of inconsistent shapes.
  • stochastic growth has output variable cell geometry RO:0002234

    Stochastic growth produces variable cell geometry.

    • DOI:10.1111/j.1574-6976.2011.00298.x coryneform morphology Supports irregular coryneform-like morphology arising from polar/apical growth without strong lateral patterning.
  • variable cell geometry manifests as irregular shaped METPO:2007400

    Variable geometry across cells manifests the irregular-shaped trait.

    • DOI:10.1146/annurev-cellbio-101011-155745 cell shape is genetically determined Supports the trait endpoint.
  • loss of MreB function disrupts MreB cytoskeletal function

    Inhibition or depletion of MreB removes curvature sensing and localized cell-wall insertion control.

    • DOI:10.1101/2024.11.22.624946 MreB filaments sense curvature and direct localized cell-wall insertion; A22 inhibition of MreB polymerization alters width and causes rounding/loss of rod shape.
  • loss of MreB function causes irregular shaped biolink:causes

    Loss of MreB-mediated localized PG insertion removes rod-shape maintenance, yielding rounding and heterogeneous morphologies.

    • DOI:10.1101/2024.11.22.624946 Inhibition of MreB polymerization causes rounding/loss of rod shape across model bacteria; a broadly conserved shape-maintenance module.
  • peptidoglycan synthase-hydrolase imbalance contributes to reduced cell-wall patterning RO:0002326

    Loss of coordination between peptidoglycan synthases and hydrolases degrades spatial control of wall synthesis.

    • DOI:10.1038/s41467-023-41082-3 Coordinated peptidoglycan synthases and hydrolases stabilize the bacterial cell wall; uncoupling them (e.g. excess hydrolase activity) accelerates loss of regular shape as a general loss-of-patterning mechanism.
  • perturbation of polar growth determinants disrupts polarized growth organization

    Disruption of apical polar growth determinants disorganizes the tip-organizing center and wall-synthesis focusing.

    • DOI:10.21203/rs.3.rs-3811693/v1 Apical determinants stabilize the tip-organizing center; their perturbation is associated with abnormal branching and mispatterned wall synthesis in filamentous bacteria.
  • perturbation of polar growth determinants has output variable cell geometry RO:0002234

    Mispatterned apical wall synthesis from disrupted polar growth produces irregular, branched/bulged geometry.

    • DOI:10.21203/rs.3.rs-3811693/v1 Partial depletion of the polar scaffold DivIVA causes hyphal bulging and irregular branching, an irregular-shape outcome of disorganized polar growth.
  • wall-less (L-form) state manifests as irregular shaped METPO:2007400

    Absence of a cylindrical wall removes canonical shape constraints, yielding irregular, amoeboid morphology.

    • DOI:10.1038/s42003-024-07279-y Wall-less L-form cells have heterogeneous, amoeboid morphology; loss of the rigid wall removes shape constraints, a general consequence of wall absence.

Provenance

Source
METPO (2025-11-25)
Definition source
DOI:10.1146/annurev-cellbio-101011-155745

Parent traits (1)

Synonyms (1)

  • irregular RELATED_SYNONYM · metpo.owl

kg-microbe context

Matched 1 kg-microbe node via direct_metpo.

  • METPO:1000691 [-4.712, -0.924, -1.303, -1.253, …]

512-dim DeepWalkSkipGramEnsmallen embedding from kg-microbe (2026-04-25).

Nearest neighbors in embedding space

Top-8 cosine-similar METPO traits from the 2026-04-25 deepwalk (512-D).

Deep research

Generated by just research-trait; source: research/traits/morphology/irregular_shaped-deep-research-falcon.md

Unreviewed literature output — not curated TraitMech content Ontology identifiers suggested below have not been resolved against their ontologies, and some are known to be wrong. Check any CURIE against the source before using it. 
# Curation report: microbial trait “irregular shaped”

**Trait:** “irregular shaped”  
**Identifier:** **METPO:1000691**  
**Category:** MORPHOLOGY; **term kind:** CLASS; **mapping:** REVIEWED  
**Provided definition:** “A cell shape lacking a consistent geometric form across individual cells of a population.”  
**Parent:** METPO:1000666; **synonym:** irregular

## 1. Scope and current mechanistic interpretation

The best-supported interpretation is a **population-level failure of shape homeostasis**, not merely a noncanonical shape. Cells should vary substantially in contour, local width, curvature, branching, bulging, or pole geometry such that no consistent sphere, rod, curved rod, helix, filament, or other reproducible geometry describes the population.

For most walled bacteria, the proximate physical determinant is the peptidoglycan (PG) sacculus. Shape depends less on unusual PG chemistry than on **where and when synthesis, cleavage, and cross-linking occur**. In canonical rods, MreB-associated elongasomes pattern lateral PG insertion, whereas FtsZ-associated divisomes organize septal PG synthesis. Loss of this spatial coordination can therefore produce nonuniform, irregular contours even when PG synthesis continues. This supports the existing graph’s high-level mechanism, “loss of patterning → irregular morphology.” (caccamo2018themolecularbasis pages 1-2, kysela2016diversitytakesshape pages 4-5, shi2018howtobuild pages 2-3)

### Boundary cases

- **Stable curved, helical, branched, prosthecate, club-shaped, or V-shaped cells:** exclude when the form is reproducible and species-typical. These are noncanonical but not necessarily irregular.
- **Pleomorphism:** overlaps strongly, but is broader; it may include regulated transitions among several reproducible forms. Curate as irregular only when within-population geometric inconsistency is demonstrated.
- **Filamentation:** division failure primarily changes length. It is insufficient by itself unless cells also develop variable widths, bulges, branching, or inconsistent contours.
- **L-forms/spheroplasts:** important boundary evidence. L-forms lack PG, are pleomorphic and osmotically sensitive, and proliferate by irregular blebbing/tubulation. They support the principle that loss of the shape-bearing wall causes irregularity, but should not automatically be merged with irregular morphology in intact, walled cells. (errington2017cellwalldeficientlform pages 4-5, errington2017cellwalldeficientlform pages 1-2)
- **Size heterogeneity or asymmetric division:** not equivalent to irregular shape. Mycobacteria can show more than a twofold difference between fast- and slow-growing poles while retaining an overall rod-like geometry. (joyce2012celldivisionsite pages 1-2)
- **Assay artifacts:** apparent irregularity caused by fixation, osmotic shock, stationary-phase degeneration, segmentation errors, or mixed taxa should be excluded unless experimentally controlled.

## 2. Candidate nodes grouped by type

Ontology grounding is deliberately conservative. Labels without verified stable identifiers should remain label-only until checked against the project’s ontology release.

### Trait and taxon nodes

- **irregular shaped — METPO:1000691**
- *Escherichia coli*, *Bacillus subtilis*, *Caulobacter crescentus*, *Mycobacterium smegmatis*, *Corynebacterium glutamicum*, *Campylobacter jejuni*, *Helicobacter pylori*, *Streptomyces coelicolor* — use verified **NCBITaxon** identifiers at YAML-authoring time.

### Cellular structures and localizations

- peptidoglycan sacculus / bacterial cell wall — GO-groundable
- cytoplasmic membrane — GO-groundable
- cell pole; old pole; new pole — GO-groundable where matching terms exist
- division septum / mid-cell — GO-groundable
- intracellular membrane domain (IMD) — label-only candidate
- elongasome / Rod complex — GO-groundable if the desired ontology release contains the complex term
- divisome / FtsZ ring — GO-groundable
- polarisome — GO-groundable or label-only depending on release

### Genes, proteins, enzymes, and complexes

- **MreB**, bacterial actin homolog
- **MreC, MreD, RodZ, RodA** and PBP2; lateral-wall Rod complex
- **FtsZ**, FtsA, FtsW, FtsI/PBP3; divisome/septal PG synthesis
- **DivIVA/Wag31**; polar growth scaffold in Actinobacteria
- **MurG**; terminal cytoplasmic enzyme in PG-precursor synthesis
- **PBP1a**; bifunctional PG synthase implicated in polar/septal synthesis
- **AccA3/ACCase complexes**; fatty-acid and mycolic-acid precursor metabolism
- **Pgp1, Pgp2**; PG hydrolases shaping *C. jejuni*
- *C. jejuni* proteins **CJJ81176_0166, CJJ81176_1104, CJJ81176_1105, CJJ81176_1228**; retain locus labels unless verified UniProt accessions are added
- **CcmA** bactofilin and M23 peptidases in curved/helical bacteria
- **SepF**, Min proteins, SulA, ZapD/YacF; division-positioning/regulatory boundary nodes

### Chemicals and metabolites

- **peptidoglycan** — ChEBI-groundable

Showing the first 60 of 238 lines of findings; the linked file also carries the run's front matter and the prompt it was given — read the full report.

Curation history

  1. · SEEDED_FROM_METPO · seed_from_metpo

    imported from data/raw/metpo.owl (CLASS)

  2. · CURATED_CAUSAL_GRAPH · claude

    Added DOI-backed definition and causal graph linking reduced cell-wall patterning and stochastic growth to irregular morphology.

  3. · GROUND_CAUSAL_PREDICATES · claude

    Grounded 2 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (RO:0002327×1, METPO:2000202×1).

  4. · GROUND_CAUSAL_PREDICATES · claude

    Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (METPO:2007400×1).

  5. · ENRICH_CAUSAL_GRAPH · claude

    Added 6 evidence-backed generic edges (6 new nodes) from the deep-research report.

  6. · GROUND_CAUSAL_PREDICATES · claude

    Grounded 4 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (biolink:causes×1, RO:0002326×1, METPO:2000202×1, METPO:2007400×1).

  7. · MIGRATE_MICROBE_DOMAIN_EDGES · claude

    Re-grounded 2 causal edge(s) off microbe-domain METPO predicates (2 to has output), issue 301. The previous predicates are transitively rdfs:subPropertyOf METPO:2000001, whose rdfs:domain is METPO:1000525 (microbe), so a causal-graph subject entailed that the subject IS a microbe; CausalNodeTypeEnum has no organism member, so no such edge could ever satisfy the domain. Edge directions are unchanged - this pass only relabels and re-grounds. RO:0002234 (has output) is used where the subject is an activity, since biolink gives it the domain 'biological process or activity'; the METPO replacements are proposed in proposals/metpo_traitmech_v8 and v9 and are placeholder ids until METPO mints them.