bacterial microcompartment

GO:0031469 · Microcompartment · Protein shelled organelle · Proposed

A bacterial protein-shelled organelle in which a selectively permeable polyhedral shell encapsulates pathway enzymes to segregate segments of metabolism from the cytosol. [GO:0031469]

Synonyms: BMC; metabolosome

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

Components

Component	Type	Part of / acts on	Grounding	Essential	Role
BMC-H facet shell proteins	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	ESSENTIAL	Hexameric single-domain shell proteins that tile the polyhedral shell facets around the encapsulated enzyme cargo. `DOI:10.1038/nrmicro.2018.10` Kerfeld et al. 2018 review BMC-H proteins as hexameric shell tiles that form microcompartment facets. `DOI:10.1126/science.aan3289` Sutter et al. 2017 resolved BMC-H proteins in an intact Haliangium ochraceum BMC shell.
BMC-T gated shell proteins	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	CONDITIONAL	Pseudohexameric tandem-domain shell proteins that can form trimers or double trimers and introduce larger gated pores. `DOI:10.1038/nrmicro.2018.10` Kerfeld et al. 2018 review BMC-T proteins as pseudohexameric tandem-domain shell proteins with gated pores in some BMCs. `DOI:10.1016/j.str.2019.01.017` Greber et al. 2019 used cryo-EM to analyze BMC-T interactions in the Haliangium ochraceum shell.
BMC-P vertex shell proteins	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	CONDITIONAL	Pentameric shell proteins that cap polyhedral vertices and help close the proteinaceous organelle shell. `DOI:10.1038/nrmicro.2018.10` Kerfeld et al. 2018 review BMC-P proteins as pentamers placed at the vertices of BMC shells. `DOI:10.1126/science.aan3289` Sutter et al. 2017 extracted the BMC-P vertex protein structure from the intact Haliangium ochraceum shell.
encapsulated lumen enzyme cargo	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	CONDITIONAL	Lineage- and locus-specific enzymes enclosed by the shell; their identities define carboxysome, propanediol, ethanolamine, and other BMC metabolic types. `DOI:10.1038/nrmicro.2018.10` Kerfeld et al. 2018 review the different enzymes encapsulated by carboxysome and metabolosome BMCs. `DOI:10.1038/s41467-021-24126-4` Sutter et al. 2021 cataloged BMC locus diversity by combining shell proteins with adjacent signature enzymes and auxiliary genes.

Taxonomic distribution

NCBITaxon:2 Bacteria — VARIABLE: Bacterial microcompartment loci are widespread but patchily distributed across bacterial genomes. [DOI:10.1038/s41467-021-24126-4]

Canonical examples

NCBITaxon:502025 Haliangium ochraceum DSM 14365 — The Haliangium ochraceum HO shell was used to solve an intact 6.5-MDa bacterial microcompartment shell structure. [DOI:10.1126/science.aan3289]

Functions

metabolic pathway encapsulation — The protein shell spatially segregates enzyme cargo so BMCs can concentrate useful pathway intermediates or retain toxic and volatile ones.
- DOI:10.1038/nrmicro.2018.10 Kerfeld et al. 2018 review BMCs as organelles that encapsulate enzymes for autotrophic carbon fixation and heterotrophic substrate catabolism.
selective metabolite permeability — Small pores through BMC-H and BMC-T shell tiles control the movement of substrates, products, cofactors, and volatile intermediates across the shell.
- DOI:10.1016/j.str.2019.01.017 Greber et al. 2019 analyzed BMC-T pores in intact Haliangium shells and modeled them as a gated permeability route through the shell.
- DOI:10.1038/nrmicro.2018.10 Kerfeld et al. 2018 review BMC shell proteins as selectively permeable pore-containing tiles.

Mechanism graphs

BMC shell proteins close a selectively permeable enzyme compartment (FUNCTION)

BMC-H, BMC-T, and BMC-P proteins assemble into a closed polyhedral shell. The shell encapsulates locus-specific enzymes and uses small pores through its shell tiles to couple pathway sequestration with selective metabolite exchange.

Subject	Predicate	Object	Evidence
BMC-H facet shell proteins	tile facets of	bacterial microcompartment	`DOI:10.1126/science.aan3289` The Haliangium ochraceum intact-shell structure placed BMC-H proteins in the shell facet lattice.
BMC-T gated shell proteins	form gated pores in	bacterial microcompartment	`DOI:10.1016/j.str.2019.01.017` Greber et al. 2019 resolved BMC-T double trimers and the variable pores in the Haliangium ochraceum shell.
BMC-P vertex shell proteins	cap vertices of	bacterial microcompartment	`DOI:10.1038/nrmicro.2018.10` Kerfeld et al. 2018 review BMC-P proteins as pentameric vertex caps.
bacterial microcompartment	encapsulates	encapsulated lumen enzyme cargo	`DOI:10.1038/nrmicro.2018.10` Kerfeld et al. 2018 compare carboxysome and metabolosome enzyme cargo in BMC interiors.
bacterial microcompartment	selectively exchanges	metabolic intermediates	`DOI:10.1016/j.str.2019.01.017` Greber et al. 2019 modeled a BMC-T pore gate in the intact-shell context.
encapsulated lumen enzyme cargo	catalyzes	encapsulated metabolic pathway	`DOI:10.1038/s41467-021-24126-4` Sutter et al. 2021 used shell proteins, signature enzymes, and auxiliary genes to classify BMC metabolic loci.

Evidence

DOI:10.1038/nrmicro.2018.10 Kerfeld CA, Aussignargues C, Zarzycki J, Cai F and Sutter M 2018, Bacterial microcompartments, Nature Reviews Microbiology.
DOI:10.1038/s41467-021-24126-4 Sutter M et al. 2021, A catalog of the diversity and ubiquity of bacterial microcompartments, Nature Communications.
DOI:10.1126/science.aan3289 Sutter M et al. 2017, Assembly principles and structure of a 6.5-MDa bacterial microcompartment shell, Science.
DOI:10.1016/j.str.2019.01.017 Greber BJ, Sutter M and Kerfeld CA 2019, The Plasticity of Molecular Interactions Governs Bacterial Microcompartment Shell Assembly, Structure.

Curation history

2026-09-06T17:04:56Z claude · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-06T17:06:58Z claude · EXPANDED_RECORD — Added BMC synonymy, organelle parentage, generic BMC-H/BMC-T/BMC-P shell and lumen-cargo components, bacterial taxonomic scope, a Haliangium ochraceum shell example, encapsulation and permeability functions, core evidence, and a protein-shell encapsulation graph.
2026-09-06T17:08:19Z claude · REVIEW_ISSUE_209 — Resolved issue #209 by changing metabolosome from BROAD_SYNONYM to NARROW_SYNONYM because metabolosomes are the catabolic subset of bacterial microcompartments.

Source: data/structures/microcompartment/bacterial_microcompartment.yaml