| Expression strain |
Induction method |
Advantages |
Disadvantages |
| BL21 |
Infection/induction with Lambda bacteriophage CE6 |
Tightest control of
Un-induced expression |
The process of induction is tedious and the induction is not as efficient as DE3 derivatives |
| BL21(DE3) |
sopropyl-1-thio-β-Dgalactopyranoside
(IPTG)
induction of T7
polymerase from lacUV5
promoter |
High level of protein expression |
Leaky expression of T7
polymerase can lead to
uninduced expression of
potentially toxic proteins |
| BL21(DE3)pLysS |
IPTG induction of T7 polymerase |
Ease of induction |
Slight inhibition of induced
expression when
compared with BL21(DE3) |
| Lemo21(DE3) |
IPTG induction of T7 polymerase |
Optimizes overexpression of any given protein using only a single strain. Outperforms other systems in its ability to maximize the production of both routine and difficult-to-overexpress proteins. |
The exact insight in the mechanism by which optimized expression yields are achieved in Lemo21(DE3) is lacking. It is not sure, whether the over expressed proteins are suitable for functional and structural studies. |
| BL21-AI |
Induction of T7 polymerase with IPTG and arabinose |
Promotes tight regulation and high yields, especially used for high level expression of toxic protein |
Testing against a wider variety of proteins is necessary to demonstrate broad utility |
| C41(DE3) and C43 (DE3) |
IPTG induction of T7 polymerase |
The mutant strains C41(DE3) and C43(DE3) can minimize the phenomenon of plasmid instability for toxic proteins |
Testing against a wider variety of proteins is required to demonstrate the broad utility |
| Tuner(DE3), and Tuner(DE3)pLysS |
IPTG inducible T7 polymerase |
The lac permease (lacY) mutation allows uniform entry of IPTG into all
cells in the population. Expression can be regulated from very low expression levels up to the robust. Tuner(DE3)pLysS helps in tighter control of over expression |
Different studies are to be carried out to understand the wider usage of the strain |
| Rosetta2 and Rosetta pLysS |
IPTG inducible T7 polymerase |
These strains are designed to enhance the expression of eukaryotic proteins that contain codons rarely used in E. coli. |
The codon specificity might cause different problems when the proteins are expressed in high levels. |
| BL21 CodonPlus RIL and CodonPlus(DE3)–RIL/RIPL |
IPTG inducible T7 polymerase |
|
|
