Protein families forming the microcompartment shell
The shells of diverse microcompartments are composed of members of three protein families: the BMC domain protein family, the inconsistently named CsoS4 / CcmL / EutN / OrfAB family, and the encapsulins/linocin-like proteins.
The BMC protein family
In microcompartment shells that have been studied, the major constituents are proteins belonging to the Bacterial Micro-Compartment (BMC) family. The crystal structures of a number of BMC proteins have been determined and invariably reveal assembly into cyclical hexamers with a small pore in the center.
The CsoS4 family
Recent structures have revealed either a pentameric or hexameric structure in this family. In icosahedral or quasi-icosahedral carboxysomes, it is likely that the pentameric form is positioned at the vertices.
Encapsulins are a large and widely distributed family of proteins and are present in most bacteria and have been identified in Candidatus methanoregula, a species of archaea. They were originally called linocin-like proteins and thought to be a group of bacterial antibiotics, since they showed bacteriostatic activity in culture. However, structural analysis showed these to form a spherical nanocompartment that contains enzymes involved in the defenses against oxidative stress.
A recent survey indicated seven different metabolic systems encapsulated by microcompartment shells. Three are characterized:
Some bacteria can use 1,2-propanediol as a carbon source. They express a microcompartment to encapsulate a number of enzymes used in this pathway. The Pdu compartment is constructed by a set of 21 genes in a single chromosomal locus. These genes are sufficient for assembly of the microcompartment since they can be transferred between bacteria and will produce a functional structure in the recipient.
- Bobik, T. A. (2007). "Bacterial Microcompartments" (PDF). Microbe (Am Soc Microbiol) 2: 25–31.
- Yeates TO, Kerfeld CA, Heinhorst S, Cannon GC, Shively JM (August 2008). "Protein-based organelles in bacteria: carboxysomes and related microcompartments". Nature Reviews Microbiology 6 (9): 681–691. PMID 18679172. doi:10.1038/nrmicro1913.
- Sutter M, Boehringer D, Gutmann S et al. (August 2008). "Structural basis of enzyme encapsulation into a bacterial nanocompartment". Nature Structural & Molecular Biology 15 (9): 939–947. PMID 18758469. doi:10.1038/nsmb.1473.
- Vernizzi G, Sknepnek R, Olvera de la Cruz, M (2011). "Platonic and Archimedan geometries in multi-component elastic membranes". Proceedings of the National Academy of Sciences of the United States of America 108 (11): 4292–4296. PMC 3060260. PMID 21368184. doi:10.1073/pnas.1012872108.
- Badger MR, Price GD (February 2003). "CO2 concentrating mechanisms in cyanobacteria: molecular components, their diversity and evolution". J. Exp. Bot. 54 (383): 609–22. PMID 12554704. doi:10.1093/jxb/erg076.
- Sampson EM, Bobik TA (April 2008). "Microcompartments for B12-dependent 1,2-propanediol degradation provide protection from DNA and cellular damage by a reactive metabolic intermediate". J. Bacteriol. 190 (8): 2966–71. PMC 2293232. PMID 18296526. doi:10.1128/JB.01925-07.
- Parsons JB, Dinesh SD, Deery E et al. (May 2008). "Biochemical and structural insights into bacterial organelle form and biogenesis". J. Biol. Chem. 283 (21): 14366–75. PMID 18332146. doi:10.1074/jbc.M709214200.
- Penrod JT, Roth JR (April 2006). "Conserving a volatile metabolite: a role for carboxysome-like organelles in Salmonella enterica". J. Bacteriol. 188 (8): 2865–74. PMC 1447003. PMID 16585748. doi:10.1128/JB.188.8.2865-2874.2006.