Protein production

There are also significant applications for expression systems in industrial fermentation, notably the production of biopharmaceuticals such as human insulin to treat diabetes, and to manufacture enzymes.

Commonly used protein production systems include those derived from bacteria,[2][3] yeast,[4][5] baculovirus/insect,[6] mammalian cells,[7][8] and more recently filamentous fungi such as Myceliophthora thermophila.

[9] When biopharmaceuticals are produced with one of these systems, process-related impurities termed host cell proteins also arrive in the final product in trace amounts.

Common DNA sources and delivery mechanisms are viruses (such as baculovirus, retrovirus, adenovirus), plasmids, artificial chromosomes and bacteriophage (such as lambda).

Nonetheless, bacterial expression has the advantage of easily producing large amounts of protein, which is required for X-ray crystallography or nuclear magnetic resonance experiments for structure determination.

To address these concerns, expressions systems using multiple eukaryotic cells were developed for applications requiring the proteins be conformed as in, or closer to eukaryotic organisms: cells of plants (i.e. tobacco), of insects or mammalians (i.e. bovines) are transfected with genes and cultured in suspension and even as tissues or whole organisms, to produce fully folded proteins.

[3] For example, a DNA sequence for a protein of interest could be cloned or subcloned into a high copy-number plasmid containing the lac (often LacUV5) promoter, which is then transformed into the bacterium E. coli.

The C. glutamicum species is widely used for producing glutamate and lysine,[16] components of human food, animal feed and pharmaceutical products.

[citation needed] The non-pathogenic and gram-negative bacteria, Pseudomonas fluorescens, is used for high level production of recombinant proteins; commonly for the development bio-therapeutics and vaccines.

[4][5] Filamentous fungi, especially Aspergillus and Trichoderma, have long been used to produce diverse industrial enzymes from their own genomes ("native", "homologous") and from recombinant DNA ("heterologous").

[25] Leishmania tarentolae (cannot infect mammals) expression systems allow stable and lasting production of proteins at high yield, in chemically defined media.

[citation needed] The most common mammalian expression systems are Chinese Hamster ovary (CHO) and Human embryonic kidney (HEK) cells.

Central dogma depicting transcription from DNA code to RNA code to the proteins in the second step covering the production of protein.
Central dogma depicting transcription from DNA code to RNA code to the proteins in the second step covering the production of protein.
E. coli , one of the most popular hosts for artificial gene expression.