- Prokaryotic expression systems are powerful tools used to produce recombinant proteins by utilizing the cellular machinery of bacteria.
- These systems are favored for their simplicity, rapid growth rates, ease of genetic manipulation, and cost-effectiveness, making them ideal for both laboratory research and large-scale industrial production.
- In a typical prokaryotic expression setup, a gene of interest is inserted into a plasmid vector, introduced into a bacterial host, and induced to produce the desired protein under controlled conditions.
- The most widely used prokaryotic host is Escherichia coli, owing to its well-characterized genetics, broad range of available strains, and extensive collection of expression vectors. E. coli is particularly suited for producing large quantities of relatively simple, non-glycosylated proteins quickly and at low cost.
- However, other prokaryotic hosts also offer important advantages. Bacillus subtilis, a Gram-positive bacterium, is often employed when secretion of proteins into the culture medium is desired, simplifying downstream purification processes. It also has a natural ability to secrete large amounts of protein and is free from endotoxins, which is advantageous for therapeutic applications.
- Corynebacterium glutamicum is another example, increasingly explored for the production of industrial enzymes and amino acids, as well as recombinant proteins that may be toxic to E. coli.
- In some cases, even photosynthetic bacteria like Synechocystis are used for specialized purposes, such as studying photosynthetic proteins or biofuel production.
- While prokaryotic systems offer speed and scalability, they have limitations, particularly in expressing eukaryotic proteins that require complex post-translational modifications such as glycosylation or specific disulfide bond patterns. Proteins may also form insoluble aggregates (inclusion bodies) or misfold when overexpressed in bacterial hosts.
- Strategies like the use of fusion tags, co-expression of molecular chaperones, or secretion into the periplasmic space help mitigate some of these issues. Nevertheless, the versatility and efficiency of prokaryotic expression systems ensure their continuing central role in molecular biology, biotechnology, and pharmaceutical industries.
