cellulosome

GO:0043263 · Other · Multiprotein complex · Proposed

An extracellular membraneless organelle built around scaffoldin and dockerin-bearing enzymes that synergistically degrade insoluble plant-cell-wall polysaccharides. [GO:0043263]

Synonyms: cellulosomal complex; multienzyme cellulolytic complex

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

Components

Component	Type	Part of / acts on	Genes	Essential	Role
primary scaffoldin	Protein	part of	cipA, scaA	ESSENTIAL	Presents cohesin modules that organize dockerin-bearing enzymes into a higher-order extracellular complex. `DOI:10.1146/annurev-biochem-091208-085603` Fontes and Gilbert 2010 review scaffoldins as the proteins that organize cohesin-dockerin enzyme assembly in cellulosomes.
dockerin-bearing plant-cell-wall hydrolases	Protein	part of	celA, celS, xyn	CONDITIONAL	Catalytic cellulases, xylanases, and accessory enzymes that dock onto scaffoldin cohesins and degrade plant cell-wall polysaccharides. `DOI:10.1146/annurev.micro.57.030502.091022` Bayer et al. 2004 review cellulosomes as scaffoldin-organized assemblies of multiple dockerin-containing carbohydrate-active enzymes.
cell-surface anchoring scaffoldins	Protein	part of		CONDITIONAL	Anchor scaffoldin-enzyme assemblies to bacterial surface layers in cell-associated cellulosome systems. `DOI:10.1146/annurev-biochem-091208-085603` Fontes and Gilbert 2010 review cell-surface anchoring scaffoldins and multi-scaffoldin architectures in natural cellulosomes.

Organism-specific protein examples

Named proteins in which each component's role was established, with the organism the evidence comes from. The component above is the taxon-agnostic family; these are the specific entries behind it.

primary scaffoldin

Accession	Protein	Gene	Organism	Entry
`UniProtKB:Q06851`	Cellulosomal-scaffolding protein A	cipA	Acetivibrio thermocellus ATCC 27405 (`NCBITaxon:203119`)	REVIEWED
Role and evidence (1 reference) The single reviewed UniProtKB entry for gene cipA in Acetivibrio thermocellus ATCC 27405, a taxon this record names. Identifier for the component's declared gene symbol; it is not itself evidence that the protein is part of this structure. `https://www.uniprot.org/uniprotkb/Q06851` UniProtKB reviewed (Swiss-Prot) entry Q06851, the single reviewed entry for gene cipA in Acetivibrio thermocellus ATCC 27405. Establishes the accession and gene identity only; the component's membership in this structure rests on the record's own sources.

dockerin-bearing plant-cell-wall hydrolases

Accession	Protein	Gene	Organism	Entry
`UniProtKB:P0C2S2`	Endoglucanase A	celA	Acetivibrio thermocellus (`NCBITaxon:1515`)	REVIEWED
Role and evidence (1 reference) The single reviewed UniProtKB entry for gene celA in Acetivibrio thermocellus, a taxon this record names; other reviewed entries for this symbol exist on sub-strain nodes and this is the one at the taxon the record names. Identifier for the component's declared gene symbol; it is not itself evidence that the protein is part of this structure. `https://www.uniprot.org/uniprotkb/P0C2S2` UniProtKB reviewed (Swiss-Prot) entry P0C2S2, the single reviewed entry for gene celA in Acetivibrio thermocellus. Establishes the accession and gene identity only; the component's membership in this structure rests on the record's own sources.
`UniProtKB:P0C2S5`	Cellulose 1,4-beta-cellobiosidase (reducing end) CelS	celS	Acetivibrio thermocellus (`NCBITaxon:1515`)	REVIEWED
Role and evidence (1 reference) The single reviewed UniProtKB entry for gene celS in Acetivibrio thermocellus, a taxon this record names; other reviewed entries for this symbol exist on sub-strain nodes and this is the one at the taxon the record names. Identifier for the component's declared gene symbol; it is not itself evidence that the protein is part of this structure. `https://www.uniprot.org/uniprotkb/P0C2S5` UniProtKB reviewed (Swiss-Prot) entry P0C2S5, the single reviewed entry for gene celS in Acetivibrio thermocellus. Establishes the accession and gene identity only; the component's membership in this structure rests on the record's own sources.

Taxonomic distribution

NCBITaxon:2 Bacteria — VARIABLE: Cellulosomes occur in a subset of anaerobic plant-polysaccharide-degrading bacteria and are absent from most bacterial lineages. [DOI:10.1146/annurev-biochem-091208-085603]

Canonical examples

NCBITaxon:1515 Acetivibrio thermocellus — The cited literature studies this organism under the Clostridium thermocellum name; it is the prototype cellulosome-forming bacterium. [DOI:10.1146/annurev.micro.57.030502.091022]

Functions

plant cell wall polysaccharide degradation — Scaffoldin-bound carbohydrate-active enzymes cooperate to hydrolyze insoluble cellulose and hemicellulose.
- DOI:10.1146/annurev-biochem-091208-085603 Fontes and Gilbert 2010 review the spatial organization of cellulosomal enzymes for synergistic plant cell-wall deconstruction.

Mechanism graphs

Cohesin-dockerin binding assembles a cellulose-degrading machine (ASSEMBLY)

A primary scaffoldin concentrates dockerin-bearing hydrolases through cohesin-dockerin interactions, and the assembled complex binds insoluble cellulose so its enzymes can hydrolyze plant cell-wall polysaccharides cooperatively.

Subject	Predicate	Object	Evidence
dockerin-bearing hydrolases	bind	primary scaffoldin	`DOI:10.1073/pnas.1936124100` Carvalho et al. 2003 established the cohesin-dockerin complex as the structural basis of cellulosome assembly.
primary scaffoldin	organizes	cohesin-dockerin-bound enzyme scaffold	`DOI:10.1146/annurev-biochem-091208-085603` Fontes and Gilbert 2010 review modular scaffoldins as the organizers of natural cellulosomes.
cell-surface anchoring scaffoldins	anchor	cellulosome	`DOI:10.1146/annurev-biochem-091208-085603` Fontes and Gilbert 2010 review anchoring scaffoldins in cellulosome-producing bacteria.
cohesin-dockerin-bound enzyme scaffold	forms	cellulosome	`DOI:10.1146/annurev.micro.57.030502.091022` Bayer et al. 2004 review cellulosomes as multienzyme complexes assembled by cohesin-dockerin interactions.
cellulosome	binds	plant cell wall polysaccharide	`DOI:10.1146/annurev-biochem-091208-085603` Fontes and Gilbert 2010 review the carbohydrate-binding and catalytic modules that focus cellulosomes on plant cell walls.
dockerin-bearing hydrolases	hydrolyze	plant cell wall polysaccharide	`DOI:10.1146/annurev.micro.57.030502.091022` Bayer et al. 2004 review cellulases and hemicellulases as catalytic constituents of cellulosomes.
cellulosome	enables	plant cell wall polysaccharide degradation	`DOI:10.1146/annurev-biochem-091208-085603` Fontes and Gilbert 2010 review cellulosomes as highly efficient nanomachines for plant cell-wall complex carbohydrate degradation.

Evidence

DOI:10.1146/annurev-biochem-091208-085603 Fontes CMGA and Gilbert HJ 2010, Cellulosomes: Highly Efficient Nanomachines Designed to Deconstruct Plant Cell Wall Complex Carbohydrates, Annual Review of Biochemistry.
DOI:10.1146/annurev.micro.57.030502.091022 Bayer EA, Belaich JP, Shoham Y and Lamed R 2004, The cellulosomes: multienzyme machines for degradation of plant cell wall polysaccharides, Annual Review of Microbiology.
DOI:10.1073/pnas.1936124100 Carvalho et al. 2003 solved a cohesin-dockerin complex that revealed the physical interaction used to assemble cellulosomes.

Curation history

2026-09-06T07:14:05Z claude · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-06T07:16:46Z claude · EXPANDED_RECORD — Added synonyms, parentage, components, taxonomy, a canonical example, function, evidence, and a source-bounded mechanism graph.
2026-09-08T07:40:02Z uniprot_genes · SEED_PROTEIN_EXAMPLES — #183: added 3 protein example(s) by resolving each of the component's declared gene symbols to the single reviewed UniProtKB entry for that symbol in a taxon this record names, deduplicated by accession. Symbols resolving to more than one reviewed entry were skipped rather than chosen between.

Source: data/structures/other/cellulosome.yaml