Generation and characterization of self-assembled protein nanocages based on β-carboxysomes in Escherichia coli

Self-assembly is a powerful means to create new materials and new catalysts. The advantages of biological self-assembly are based on it being highly programmable and prone to multilevel regulation, which can lead to multiple and complex functions. The self-assembly of carboxysomes in cyanobacteria enables the carboxysomes to enrich carbon dioxide in their interior, resulting in the formation of a highly efficient, multiple-enzyme catalytic system. Here, we show that the construction and coexpression of all genes of the β-carboxysome from the cyanobacterium Thermosynechococcus elongatus BP-1 can lead to the production of β-carboxysome-like structures in Escherichia coli. These shell structures were characterized intracellularly and extracellularly by transmission electron microscopy. This work lays a foundation for understanding carboxysome assembly and catalysis and the development of novel carboxysome-based nanomaterials utilizing synthetic biology.