expression of prokaryotic recombinant proteins
Introduction to the expression system of prokaryotic recombinant proteins with different hosts
There are different hosts in the expression system for prokaryotic recombinant proteins, including :
E. coli is one of the first and most widely used hosts for the production of recombinant proteins. This system is excellent for expressing the function of non-glycosylated proteins. Other useful prokaryotic systems for the production of recombinant protein have been mentioned above in which E.coli accounts for the most prominent bacterium.
The benefits of this system include rapid growth, high density in simple and cost-effective cell culture media, well-known genetic information, the availability of a large number of cloning carriers and host mutated strains, simple transfection, easy control of its promoter, and mass production of the recombinant proteins.
However, the prokaryotic system has some drawbacks. One of them is high cell density due to acetate formation, leading to toxicity. Also, proteins produced in inclusion bodies are often insoluble and need to be refolded. This system is unable to produce proteins possessing high disulfide bridges. Other limitations of prokaryotic expression systems include the lack of post-translational modifications, such as protein glycation, changes or replacement of amino acids due to codon preference, endotoxin contamination, destruction of external protein inserted into the host, incorrect processing due to lack of chaperones, production of inactive proteins, instability of plasmids, production of small amounts of functional proteins, accumulation of recombinant products as inclusion bodies, and difficulty in protein purification.
Among various systems that produce recombinant proteins, the eukaryotic system is more preferable compared with the prokaryotic system due to the production of abundant proteins, in particular proteins rich in di-sulfide bands, as well as post-translational modifications that occur in this system. However, prokaryotic systems are more effective in synthesizing small proteins.