endospore coat

GO:0043593 · Spore · Envelope layer · Proposed

The layer in a bacterial endospore that lies under the exosporium, and is impermeable to many toxic molecules. The coat may also contain enzymes that are involved in endospore germination. [GO:0043593]

Part of: endospore external encapsulating structure (GO:0043591)

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
endospore coat proteins	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	spoIVA, safA, cotE	dozens of proteins in Bacillus subtilis	ESSENTIAL	Morphogenetic and structural proteins that assemble into the multilayered coat shell outside the cortex, including the SpoIVA basement layer and SafA/CotE-organized inner and outer layers. `DOI:10.1038/nrmicro2921` McKenney, Driks and Eichenberger 2012 review the Bacillus subtilis coat's basement, inner, outer, and crust layers and the SpoIVA, SafA, and CotE morphogenetic proteins that organize coat assembly. `PMID:3139490` Zheng et al. identified CotE as a morphogenetic protein needed to assemble the outer Bacillus subtilis spore coat.

Taxonomic distribution

NCBITaxon:1239 Bacillota — COMMON: Endospore coats occur in endospore-forming Bacillota lineages as a mature-spore surface layer, with many non-sporulating Bacillota lacking the structure. [DOI:10.1038/nrmicro2921]

Canonical examples

NCBITaxon:1423 Bacillus subtilis — Classical model for the proteinaceous endospore coat layers organized by SpoIVA, SafA, CotE, and other coat morphogenetic proteins. [DOI:10.1038/nrmicro2921]

Functions

endospore coat permeability barrier — The multilayered endospore coat restricts lytic enzymes and large toxic molecules from accessing the dormant spore interior.
- DOI:10.1038/nrmicro2921 McKenney, Driks and Eichenberger 2012 review the bacterial endospore coat as a protective barrier outside the cortex.
- GO:0043593 GO:0043593 defines the endospore coat as impermeable to many toxic molecules.

Mechanism graphs

Endospore coat surrounds the cortex as a permeability barrier (FUNCTION)

Coat proteins assemble into a multilayered shell outside the endospore cortex within the external encapsulating structure, making a mature-spore surface barrier that restricts lytic enzymes and many toxic molecules.

Subject	Predicate	Object	Evidence
endospore coat proteins	assemble into	endospore coat	`DOI:10.1038/nrmicro2921` McKenney, Driks and Eichenberger 2012 review the morphogenetic hierarchy that builds the Bacillus subtilis spore coat layers.
endospore coat	surrounds	endospore cortex	`DOI:10.1038/nrmicro2921` McKenney, Driks and Eichenberger 2012 review the bacterial spore coat as a multilayered shell outside the cortex. `GO:0043593` GO:0043593 defines the endospore coat as a layer of the bacterial endospore.
endospore coat	excludes	enzyme and toxin barrier	`DOI:10.1038/nrmicro2921` McKenney, Driks and Eichenberger 2012 describe the coat as a barrier against lytic enzymes and large toxic molecules.
endospore coat	is part of	endospore external encapsulating structure	`GO:0043593` GO:0043593 defines the endospore coat as a bacterial endospore layer. `GO:0043591` GO:0043591 identifies the broader endospore external encapsulating structure.

Discussions

INTERPRETATION (RESOLVED): Keep the endospore coat separate from the broader endospore external encapsulating structure. GO:0043593 denotes the proteinaceous endospore coat layer, whereas GO:0043591 denotes the broader external encapsulating structure that also includes the cortex and outer endospore membrane.
CURATION_TODO (OPEN): Resolve exact source-neutral family groundings for individual endospore coat layers or protein cohorts. This pass models the endospore coat proteins as one reviewed aggregate because the mature bacterial coat is assembled from many unrelated proteins across multiple layers. A follow-up can split exact basement, inner-coat, outer-coat, or crust families where source-neutral family identifiers exist.

Evidence

GO:0043593 Gene Ontology cellular-component term for the endospore coat.
GO:0043591 Gene Ontology cellular-component term for the endospore external encapsulating structure that contains the coat.
DOI:10.1038/nrmicro2921 McKenney, Driks and Eichenberger 2012, The Bacillus subtilis endospore: assembly and functions of the multilayered coat, Nature Reviews Microbiology.
PMID:3139490 Zheng et al. 1988 identified CotE as a morphogenetic protein needed for Bacillus subtilis outer spore-coat assembly.

Curation history

2026-09-15T17:32:20Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-15T17:33:21Z codex · EXPANDED_RECORD — Added external-structure parthood, a reviewed-label-only coat-protein component, Bacillota distribution, a Bacillus subtilis example, barrier function, GO and literature evidence, a nonmechanistic coat-barrier topology graph, and boundary/grounding discussions.
2026-09-15T17:43:03Z codex · REVIEW_FIX — Resolved PR #1005 review issues #1006 and #1007 by narrowing the barrier function label to the endospore coat and adding the GO:0043591 external-structure node and parthood edge to the topology graph.

Source: data/structures/spore/endospore_coat.yaml