In
molecular biology
Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and phys ...
the Bacterial Microcompartment (BMC) domain is a
protein domain
In molecular biology, a protein domain is a region of a protein's polypeptide chain that is self-stabilizing and that folds independently from the rest. Each domain forms a compact folded three-dimensional structure. Many proteins consist of ...
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 sp ...
from other bacteria. These shell proteins form the
polyhedral 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 e ...
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 hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...
residues, characterized by β-α-β motif connected by a β-hairpin.
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