holdfast

cellstructuremech:holdfast · Other · Other · Proposed

A polar extracellular adhesive matrix of Caulobacter vibrioides composed of secreted holdfast polysaccharide that is anchored at the old cell pole or stalk tip and enables irreversible surface attachment. [DOI:10.1128/JB.00112-19]

Synonyms: Caulobacter holdfast; holdfast adhesin

UniProt location names: UniProt Consortium, CC BY 4.0. Reference label and route sources.

Components

Component	Type	Part of / acts on	Grounding	Genes	Stoichiometry	Essential	Role
holdfast polysaccharide	Polysaccharide	part of	Reviewed label only (reviewed name; no accession asserted)				Forms the extracellular adhesive matrix that binds surfaces at the old cell pole or stalk tip. `DOI:10.1128/JB.00276-19` Hershey et al. 2019 extracted C. crescentus holdfast material and surveyed the carbohydrate composition of the holdfast polysaccharide. `DOI:10.1128/mBio.00294-17` Sprecher et al. 2017 treated the Caulobacter holdfast as a localized polysaccharide adhesin whose cohesive properties are developmentally regulated.
HfaA-HfaB-HfaD holdfast anchor	Protein complex	acts on	Reviewed label only (reviewed name; no accession asserted)	hfaA, hfaB, hfaD		DISPENSABLE	Anchors the secreted holdfast matrix at the old cell pole or stalk tip so it remains attached to the cell surface. `DOI:10.1128/JB.00112-19` Sulkowski et al. 2019 analyze HfaA, HfaB and HfaD as proteins that anchor Caulobacter holdfast at the old cell pole.

Taxonomic distribution

NCBITaxon:155892 Caulobacter vibrioides — UNIVERSAL: The Caulobacter holdfast is a polar adhesin of the C. vibrioides developmental cycle, with synthesis and surface adhesion regulated by cell cycle stage and environmental cues. [DOI:10.1128/mBio.00294-17]

Canonical examples

NCBITaxon:565050 Caulobacter vibrioides NA1000 — Caulobacter vibrioides NA1000 is a standard holdfast model used to dissect holdfast anchoring, polysaccharide composition and c-di-GMP-dependent adhesiveness. [DOI:10.1128/JB.00112-19]

Functions

irreversible surface adhesion — The holdfast glues the old pole or stalk tip to abiotic surfaces during the Caulobacter surface-attachment program.
- DOI:10.1128/mBio.00294-17 Sprecher et al. 2017 studied the cohesive properties that make the Caulobacter holdfast an adhesive surface organelle.
polar holdfast anchoring — Hfa anchoring proteins retain the secreted holdfast matrix at the old cell pole or stalk tip instead of allowing it to be released into the medium.
- DOI:10.1128/JB.00112-19 Sulkowski et al. 2019 show that Hfa proteins form a multiprotein anchoring complex for old-pole holdfast retention.

Mechanism graphs

Holdfast polysaccharide is cohesion-tuned and anchored (ASSEMBLY)

HfsK responds to c-di-GMP to tune adhesive-matrix cohesion, and Hfa proteins anchor the completed holdfast at the old pole or stalk tip so it can glue the cell to abiotic surfaces.

Subject	Predicate	Object	Evidence
HfsK c-di-GMP effector	tunes cohesion of	holdfast polysaccharide	`DOI:10.1128/mBio.00294-17` Sprecher et al. 2017 link a novel c-di-GMP effector to regulated Caulobacter holdfast cohesion.
holdfast polysaccharide	forms	holdfast	`DOI:10.1128/JB.00276-19` Hershey et al. 2019 chemically analyze isolated holdfast polysaccharide.
HfaA-HfaB-HfaD holdfast anchor	anchors	holdfast	`DOI:10.1128/JB.00112-19` Sulkowski et al. 2019 characterize a multiprotein Hfa complex required for Caulobacter holdfast anchoring.
holdfast	localizes to	old pole or stalk tip	`DOI:10.1128/JB.00112-19` Sulkowski et al. 2019 focus on anchoring adhesive holdfast at the Caulobacter old cell pole.
holdfast	adheres cell to	abiotic surface	`DOI:10.1128/mBio.00294-17` Sprecher et al. 2017 investigate the Caulobacter holdfast adhesin as the developmentally regulated adhesive for surface attachment.

Discussions

CURATION_TODO (RESOLVED): Keep Hfs synthesis, export and HfsK cohesion proteins out of the component table for this first holdfast record. Hfs proteins synthesize, export or modify holdfast material before or during assembly. The HfsK effector is represented as graph machinery, Hfs synthesis/export factors are omitted until direct gene-level edges are curated, and the component table contains the holdfast polysaccharide plus the Hfa machinery that anchors the assembled adhesin.
CURATION_TODO (OPEN): Resolve exact source-neutral groundings for holdfast polysaccharide and the Hfa anchoring machinery. The record intentionally uses reviewed labels until a glycan accession for the complete holdfast polysaccharide and a source-neutral Hfa anchoring-complex identifier can be verified.

Evidence

DOI:10.1128/JB.00112-19 Sulkowski NI et al. 2019, 'A Multiprotein Complex Anchors Adhesive Holdfast at the Old Cell Pole of Caulobacter crescentus', Journal of Bacteriology.
DOI:10.1128/JB.00276-19 Hershey DM et al. 2019, 'Composition of the Holdfast Polysaccharide from Caulobacter crescentus', Journal of Bacteriology.
DOI:10.1128/mBio.00294-17 Sprecher KS et al. 2017, 'Cohesive Properties of the Caulobacter crescentus Holdfast Adhesin Are Regulated by a Novel c-di-GMP Effector Protein', mBio.

Curation history

2026-09-11T02:23:07Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-11T02:23:49Z codex · EXPANDED_RECORD — Added holdfast synonymy, extracellular-matrix parentage, holdfast polysaccharide and Hfa anchoring components, Caulobacter taxonomy, surface-adhesion and anchoring functions, a synthesis-anchoring graph, literature evidence, and grounding/boundary discussions.
2026-09-11T02:29:31Z codex · REFINED_CAUSAL_GRAPH — Narrowed the c-di-GMP-regulated holdfast cohesion node to HfsK and pointed the adhesion edge at abiotic surfaces instead of a derived surface-attached-cell state.
2026-09-11T02:33:35Z codex · ADDRESS_REVIEW — Resolved PR #392 issues #393 and #394 by removing the under-evidenced Hfs synthesis/export edge and replacing the old-cell-pole state with an old-pole-or-stalk-tip cellular-localization node.

Source: data/structures/other/holdfast.yaml