spore wall

GO:0031160 · Spore · Envelope layer · Proposed

The specialized envelope lying outside the cell membrane of a spore. [GO:0031160]

Synonyms: spore coat

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

Taxonomic distribution

NCBITaxon:6029 Microsporidia — COMMON: Infectious microsporidian spores are enclosed by a thick wall with exospore and chitin-rich endospore layers. [DOI:10.1016/j.ijpara.2005.10.005]
NCBITaxon:1239 Bacillota — COMMON: Bacterial endospore-forming lineages build an external spore wall with cortex, coat, and sometimes exosporium layers, while many Bacillota lineages have lost endospore formation. [DOI:10.1038/nrmicro2921]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — Budding-yeast model in which the ascospore wall forms as a multilaminar envelope around each meiotic spore. [DOI:10.1128/MMBR.69.4.565-584.2005]
NCBITaxon:6035 Encephalitozoon cuniculi — Microsporidian model in which the spore wall contains an outer exospore and an inner, chitin-rich endospore. [DOI:10.1016/j.ijpara.2005.10.005]
NCBITaxon:1423 Bacillus subtilis — Bacterial model for morphogenesis of the multilayered coat and cortex surrounding the dormant endospore. [DOI:10.1038/nrmicro2921]

Functions

spore wall protection — The spore wall surrounds dormant or infectious spores with a specialized envelope that contributes to resistance during dispersal or host-to-host transmission.
- DOI:10.1002/pmic.200700584 Wu et al. 2008 describe Nosema bombycis spores as protected by a thick wall containing a glycoprotein-rich exospore and chitin-rich endospore.
- DOI:10.1038/nrmicro2921 McKenney, Driks and Eichenberger 2012 review the cortex and coat layers that protect bacterial endospores.

Mechanism graphs

Microsporidian endospore and exospore form a protective wall (FUNCTION)

Microsporidian spores carry a chitin-rich endospore underneath a protein-rich exospore; together those envelope layers form the thick spore wall around the infectious spore.

Subject	Predicate	Object	Evidence
microsporidian-type endospore	is part of	spore wall	`GO:0090641` GO:0090641 places the microsporidian-type endospore as part of GO:0031160 spore wall. `DOI:10.1016/j.ijpara.2005.10.005` Peuvel-Fanget et al. 2006 assigned Encephalitozoon EnP1 and EnP2 proteins to the mature-spore endospore.
microsporidian-type exospore	is part of	spore wall	`GO:0090642` GO:0090642 places the microsporidian-type exospore as part of GO:0031160 spore wall. `DOI:10.1002/pmic.200700584` Wu et al. 2008 localized Nosema bombycis SWP32 to the exospore by immunofluorescence and immunoelectron microscopy.
microsporidian-type exospore	overlies	microsporidian-type endospore	`GO:0090642` GO:0090642 defines the exospore as the outermost microsporidian spore-wall layer above the endospore.
spore wall	provides	spore wall protection	`DOI:10.1002/pmic.200700584` Wu et al. 2008 describe the microsporidian spore wall as a thick wall with a glycoprotein-rich exospore and chitin-rich endospore. `DOI:10.1128/IAI.68.4.2268-2275.2000` Bohne et al. 2000 describe the Encephalitozoon cuniculi wall as a rigid spore wall that provides mechanical resistance.

Discussions

INTERPRETATION (RESOLVED): Do not add every lineage-specific spore-wall layer directly to the generic spore-wall has_part list. GO places the microsporidian endospore and exospore as parts of spore wall, but those layers are specific to microsporidian spores. Fungal ascospore layers remain under GO:0005619 ascospore wall and bacterial endospore layers remain under GO:0043591 endospore external encapsulating structure.
INTERPRETATION (RESOLVED): Keep the GO:0031160 spore coat synonym separate from the bacterial endospore coat record. GO:0031160 uses spore coat as an exact synonym for the broad spore wall class, whereas GO:0043593 denotes the specific bacterial endospore coat layer curated separately.

Evidence

GO:0031160 Gene Ontology cellular-component term for the spore wall.
GO:0005618 — cell wall Gene Ontology cellular-component parent term for cell walls.
GO:0005619 Gene Ontology cellular-component child term for the fungal ascospore wall.
GO:0043591 Gene Ontology cellular-component descendant for the bacterial endospore external encapsulating structure.
GO:0090641 Gene Ontology cellular-component part term for the microsporidian-type endospore.
GO:0090642 Gene Ontology cellular-component part term for the microsporidian-type exospore.
DOI:10.1016/j.ijpara.2005.10.005 Peuvel-Fanget et al. 2006 studied Encephalitozoon cuniculi spore-wall proteins associated with the mature-spore endospore.
DOI:10.1002/pmic.200700584 Wu et al. 2008, Proteomic analysis of spore wall proteins and identification of two spore wall proteins from Nosema bombycis (Microsporidia), Proteomics.
DOI:10.1128/MMBR.69.4.565-584.2005 Neiman 2005 reviews Saccharomyces cerevisiae ascospore wall assembly and mature wall layering.
DOI:10.1038/nrmicro2921 McKenney, Driks and Eichenberger 2012 review the Bacillus subtilis endospore coat and surrounding envelope layers.

Curation history

2026-09-23T22:10:32Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-23T22:12:03Z codex · EXPANDED_RECORD — Added GO synonymy, cell-wall parentage, Microsporidia and Bacillota taxonomic scope, Saccharomyces, Encephalitozoon, and Bacillus examples, a spore-wall protection function, GO/DOI evidence, a nonmechanistic microsporidian endospore/exospore wall graph, and resolved boundary decisions for lineage-specific child layers and the broad spore-coat synonym.

Source: data/structures/spore/spore_wall.yaml