Cheryl A. Kerfeld - Diversity, structure, function, assembly and engineering of bacterial microcompartments

Bacterial microcompartments are widespread metabolic modules found in at least 23 bacterial phyla. The carboxysome is the best studied bacterial microcompartment and serves to illustrate the basic principles of bacterial micrcompartment structure and function. It consists of a selectively permeable protein shell encapsulating ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and carbonic anhydrase. Cyanobacteria depend on the carboxysome to concentrate carbon dioxide near RuBisCO while minimizing the wasteful side reaction with oxygen. The carboxysome functions as an organelle but, in contrast to eukaryotic organelles, is composed entirely of protein; thousands of protein subunits self-assemble to form this ~300 MDa complex. Many bacteria assemble architecturally-related types of organelles for diverse catabolic functions. Our studies suggest that the principles of carboxysome structure, function and assembly likely extend to other bacterial microcompartments and provide the foundation for design and construction of synthetic nanoreactors based on bacterial microcompartment architecture.