BMC
SMART ACC:	SM000877
Description:	Bacterial microcompartments are primitive organelles composed entirely of protein subunits. The prototypical bacterial microcompartment is the carboxysome, a protein shell for sequestering carbon fixation reactions. These proteins for hexameric structure.
InterPro ACC:	IPR000249
InterPro abstract:	Bacterial microcompartments (BMCs) are large proteinaceous structures comprised of a roughly icosahedral shell and a series of encapsulated enzymes. The shells of BMCs are made primarily of a family of proteins whose structural core is the BMC domain, and variations upon this core provide functional diversity. This domain is found in a variety of polyhedral organelle shell proteins (CcmK), including … expand Bacterial microcompartments (BMCs) are large proteinaceous structures comprised of a roughly icosahedral shell and a series of encapsulated enzymes. The shells of BMCs are made primarily of a family of proteins whose structural core is the BMC domain, and variations upon this core provide functional diversity. This domain is found in a variety of polyhedral organelle shell proteins (CcmK), including CsoS1A, CsoS1B and CsoS1C of Thiobacillus neapolitanus (Halothiobacillus neapolitanus) and their orthologues from other bacteria [ PUBMED:30389783 PUBMED:25455419 PUBMED:30901520 ]. Some autotrophic and non-autotrophic organisms form polyhedral organelles, carboxysomes/enterosomes [ PUBMED:11722879 ]. The best studied is the carboxysome of Halothiobacillus neapolitanus, which is composed of at least 9 proteins: six shell proteins, CsoS1A, CsoS1B, CsoS1C, Cso2A, Cso2B and CsoS3 (carbonic anhydrase) [ PUBMED:14729686 PUBMED:33116131 ], one protein of unknown function and the large and small subunits of RuBisCo (CbbL and Cbbs). Carboxysomes appear to be approximately 120 nm in diameter, most often observed as regular hexagons, with a solid interior bounded by a unilamellar protein shell. The interior is filled with type I RuBisCo, which is composed of 8 large subunits and 8 small subunits; it accounts for 60% of the carboxysomal protein, which amounts to approximately 300 molecules of enzyme per carboxysome. Carboxysomes are required for autotrophic growth at low CO ₂ concentrations and are thought to function as part of a CO ₂ -concentrating mechanism [ PUBMED:15012219 PUBMED:9891798 ]. Polyhedral organelles, enterosomes, from non-autotrophic organisms are involved in coenzyme B ₁₂ -dependent 1,2-propanediol utilisation (e.g., in Salmonella enterica [ PUBMED:10498708 ]) and ethanolamine utilisation (e.g., in Salmonella typhimurium [ PUBMED:7868611 ]). Genes needed for enterosome formation are located in the 1,2-propanediol utilisation pdu [ PUBMED:10498708 PUBMED:11844753 ] or ethanolamine utilisation eut [ PUBMED:7868611 PUBMED:10464203 ] operons, respectively. Although enterosomes of non-autotrophic organisms are apparently related to carboxysomes structurally, a functional relationship is uncertain. A role in CO ₂ concentration, similar to that of the carboxysome, is unlikely since there is no known association between CO ₂ and coenzyme B12-dependent 1,2-propanediol or ethanolamine utilisation [ PUBMED:11844753 ]. It seems probable that enterosomes help protect the cells from reactive aldehyde species in the degradation pathways of 1,2-propanediol and ethanolamine [ PUBMED:11722879 ]. The BMC domain fold consists of three α-helices (designated A, B, and C) and four β-strands . Some instances of the BMC shell protein reveal a circular permutation in which a highly similar tertiary structure is built from secondary structure elements occurring in a different order. The secondary structure elements contributed by the C-terminal region of the typical BMC fold are instead contributed by the N-terminal region of the BMC circularly permuted domain [ PUBMED:18786396 PUBMED:20870711 PUBMED:19328811 ]. collapse
GO component:	bacterial microcompartment (GO:0031469)
Family alignment:	View the Family alignment or the Alignment consensus sequence
There are 13 168 BMC domains in 10 616 proteins in SMART's NRDB database.

Taxonomic distribution of proteins containing BMC domains

The tree below includes only several representative species and genera. The complete taxonomic breakdown of all proteins containing BMC domains can be accessed here. Click the counts or percentage values to display the corresponding proteins.

Predicted cellular role

Cellular role:	Metabolic

Relevant references for this domain

Primary literature for the BMC domain is listed below. Automatically-derived, secondary literature is also available.

KEGG pathways involving proteins which contain this domain

This information is based on the mapping of SMART genomic protein database to KEGG orthologous groups. Percentages are related to the number of proteins containing a BMC domain which could be assigned to a KEGG orthologous group, and not all proteins containing BMC domains. Please note that proteins can be included in multiple pathways, ie. the numbers below will not add to 100%.

KEGG pathways

Some of these pathways are included in the interactive Pathways Explorer overview maps. Select an overview map and click the button below to highlight them in iPath.

KEGG orthologous groups

Some of these KOs are included in the interactive Pathways Explorer overview maps. Select an overview map and click the button below to highlight them in iPath.

3D structures in PDB containing this domain

Links to other resources describing this domain

InterPro	IPR000249
Pfam	BMC