pilus
A proteinaceous hair-like appendage on the surface of bacteria ranging from 2-8 nm in diameter. [GO:0009289]
Synonyms: fimbria; fimbriae; fimbrium; pili
Xrefs: uniprot.location:SL-0113 — Fimbrium
Components
| Component | Type | Part of / acts on | Grounding | Genes | Stoichiometry | Essential | Role |
|---|---|---|---|---|---|---|---|
| pilus structural subunits | Protein | part of | Reviewed label only (reviewed name; no accession asserted) | ESSENTIAL | Protein subunits that polymerize into a hair-like extracellular pilus fiber on the bacterial cell surface.
|
Taxonomic distribution
NCBITaxon:562Escherichia coli — VARIABLE: Escherichia coli is used here as a directly cited model for chaperone-usher type I and P pili, without asserting that every E. coli strain carries every pilus subclass. [DOI:10.1038/nrmicro.2017.40]
Canonical examples
NCBITaxon:562Escherichia coli — Escherichia coli is a model for multiple chaperone-usher pilus subclasses, including type I pili and P pili. [DOI:10.1038/nrmicro.2017.40]
Functions
- bacterial surface interaction — Bacterial pili project from the cell surface and, depending on subtype, mediate adhesion, cell-cell interactions, biofilm formation, conjugation, DNA uptake or twitching motility.
uniprot.location:SL-0113— Fimbrium UniProt Subcellular Location entry SL-0113 summarizes adhesion, motility, cell-cell interaction, biofilm, conjugation and DNA uptake roles for bacterial pili.DOI:10.1038/nrmicro.2017.40Hospenthal, Costa and Waksman 2017 review the adhesive, motility and DNA-uptake roles of Gram-negative bacterial pili.
Mechanism graphs
Protein polymers build bacterial pili (FUNCTION)
Nonhomologous pilus structural subunits polymerize into surface-exposed protein fibers that let bacterial cells interact with surfaces, host cells, neighboring cells or extracellular DNA.
| Subject | Predicate | Object | Evidence |
|---|---|---|---|
| pilus structural subunits | polymerize into | pilus |
|
| pilus | supports | bacterial surface interaction |
|
Discussions
- CURATION_TODO (OPEN): Resolve exact source-neutral identifiers for structural pilus subunits that can be added to the generic pilus parent without conflating type-specific Fim, Pap, Pil and Csg fibers. The pilus parent record captures the proteinaceous polymer shared by bacterial pilus subclasses, while exact subunit families differ among type I, P, type IV, curli and other children.
Evidence
GO:0009289Gene Ontology cellular-component term for pilus.uniprot.location:SL-0113— Fimbrium UniProt Subcellular Location entry that maps Fimbrium to GO:0009289.DOI:10.1038/nrmicro.2017.40Hospenthal MK, Costa TRD and Waksman G 2017, 'A comprehensive guide to pilus biogenesis in Gram-negative bacteria', Nature Reviews Microbiology.
Curation history
2026-09-12T14:28:45Zcodex · CREATED_RECORD — Scaffolded by scripts/new_record.py2026-09-12T14:29:30Zcodex · EXPANDED_RECORD — Added GO synonymy, the UniProt Subcellular Location xref, a reviewed-label-only generic structural-subunit component, bacterial scope, an Escherichia coli canonical example, generic surface-interaction function, DOI/GO/UniProt evidence, a nonmechanistic pilus-polymer graph, and a boundary TODO for exact subtype-neutral subunit grounding.2026-09-12T14:35:27Zcodex · TIGHTENED_EVIDENCE_SCOPE — Narrowed the Escherichia coli canonical-example note to type I and P pili so the claim is directly supported by Hospenthal, Costa and Waksman 2017.2026-09-12T14:42:16Zcodex · ADDRESS_REVIEW — Resolved #661 by narrowing the pilus taxonomic-distribution row from all Bacteria to the directly cited Escherichia coli chaperone-usher pilus model.