- The Escherichia coli (E. coli) expression system is one of the most widely used platforms for recombinant protein production in molecular biology and biotechnology.
- E. coli is a Gram-negative, fast-growing bacterium with a simple, well-characterized genetic background, which makes it highly amenable to genetic manipulation.
- It can be cultured rapidly in inexpensive media and scaled easily from small laboratory cultures to industrial fermenters.
- Recombinant proteins are typically expressed by introducing the gene of interest into a plasmid vector under the control of strong promoters, such as the T7 promoter, and inducing expression with agents like IPTG.
- Specialized strains, such as BL21(DE3), Rosetta, and SHuffle, have been developed to optimize expression, improve protein folding, and address issues such as codon bias and disulfide bond formation.
- The main advantages of the E. coli system include its speed, cost-effectiveness, and the ability to produce high yields of relatively simple, non-glycosylated proteins. It is particularly well suited for producing enzymes, antibodies fragments (like scFvs), research reagents, and some therapeutic proteins.
- However, the system also has limitations. E. coli cannot perform most eukaryotic post-translational modifications such as glycosylation, and proteins that require complex folding or specific disulfide bonds may misfold, aggregate, or form insoluble inclusion bodies. Strategies such as fusion to solubility-enhancing tags (e.g., MBP, GST), co-expression with molecular chaperones, or targeting proteins to the periplasmic space can help address these challenges.
- Despite some biological constraints, the E. coli expression system remains a cornerstone of recombinant protein production due to its unparalleled simplicity, versatility, and efficiency.
