molecular biology Molecular biology is a branch of biology that seeks to understand the molecule, molecular basis of biological activity in and between Cell (biology), cells, including biomolecule, biomolecular synthesis, modification, mechanisms, and interactio ...

the Bacterial Microcompartment (BMC) domain is a

protein domain In molecular biology, a protein domain is a region of a protein's Peptide, polypeptide chain that is self-stabilizing and that Protein folding, folds independently from the rest. Each domain forms a compact folded Protein tertiary structure, thre ...

found in a variety of shell proteins, including CsoS1A, CsoS1B and CsoS1C of ''Thiobacillus neapolitanus'' (''Halothiobacillus neapolitanus'') and their

orthologs Sequence homology is the biological homology between DNA, RNA, or protein sequences, defined in terms of shared ancestry in the evolutionary history of life. Two segments of DNA can have shared ancestry because of three phenomena: either a spec ...

from other bacteria. These shell proteins form the

polyhedral In geometry, a polyhedron (: polyhedra or polyhedrons; ) is a three-dimensional figure with flat polygonal faces, straight edges and sharp corners or vertices. The term "polyhedron" may refer either to a solid figure or to its boundary surfa ...

structure of the

carboxysome Carboxysomes are bacterial microcompartments (BMCs) consisting of polyhedral protein shells filled with the enzymes ribulose-1,5-bisphosphate carboxylase/oxygenase ( RuBisCO)—the predominant enzyme in carbon fixation and the rate limiting ...

and related structures that plays a metabolic role in bacteria. The BMC domain consists of about 90

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...

residues, characterized by β-α-β motif connected by a

β-hairpin The beta hairpin (sometimes also called beta-ribbon or beta-beta unit) is a simple protein structural motif involving two beta strands that look like a hairpin. The motif consists of two strands that are adjacent in primary structure, oriented in ...

. The majority of the shell proteins consist of a single BMC domain in each subunit, forming a hexameric structure that assembles to form the flat facets of the polyhedral shell. To date, two shell proteins were found to consist a tandem BMC domains, of which forms a trimeric structure, giving a pseudo-hexameric appearance.

References

{{InterPro content, IPR000249 Protein domains