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Erstellt / Aktualisiert 07.06.2021 / 08.06.2021
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Factors to consider while choosing the appropriate expression system

-What type of protein do I want to express? (Origin, subcellular localization, ...)

-For what purpose? (Activity assay, "in vivo" functional studies, medical ...)

-How much protein I need= (industrial vs lab scale)

-Does my protein need post-translational modifications/ proper folding for strcture/activity? (Glycosylation, phosphorylation...)

-Do I have the appropriate facilities/equipment? (Safety hazard, culture requirements ...)

-Other factors (cost, speed, scalability, quality ...)

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Protein expression systems


Gram negative: Escherichia coli and Pseudomonas fluorescens 

Gram positiv: Bacillus subtilis

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Protein expression systems


Yeast: Saccharomyces cerevisiae, Pichia pastoris

Filamentous fungi: Aspergillus niger, Trichoderma reesei

Insect ceels: Baculovirus-based systems

Mammalian cells: transient/stable

Plants: transient/stable

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Protein expression systems


E. coli

Rabbit reticulocytes

Wheat germ


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Prokaryotic expression systems Advantages and Disadvantages

Advantages: Very high expression levels, low cost, simple culture conditions, fast cell multiplication, relative scalability

Disadvantages: Minimal post-translational modifications, inefficent disulfide bond formation, poor protein folding, 

codon usage different to eukaryotes, inclusion body formation, potential endotoxin contamination

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E. coli Advantages and Disadvantages

Advantages: Model organism, well known biochemistry and genetic, extensive resource collections (mutant strains, vectors),

optimized systems available

Disadvantages: Minimal post-translational modifications, Inefficient disulfide bond formation, poor protein folding, codon usage diffent to eukaryotes, inclusion body formation, potential endotoxin production

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Pseudomans fluorescens Advantages and Disadvantages

Advantages: Cultivated at high cell densities, better protein solubility, fermentation less dependen on oxygen concentrations, 

no acetate accumulation during fermentation, able to produce disulfide bonds in periplasm, no endotoxin production

Disadvantages: Variable yield (due to lack of understanding of biology, low plasmid stability

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B. subtilis Advantages and Disadvantages

Advantages: non-pathogenic and GRAS organism, natural protein secretion system, no significant bias in codon usage, 

better protein folding than E. coli, Coproduction of multiple proteins Bacillus megaterium

Disadvantages: optimization of protein secretion often required, degradation of heterologous proteins, instability of plasmid, 

lack of well-regulated inducible vectors