Bacterial strains for protein expression

Faculty of Science

Bacterial Strains for Protein Expression

Bacterial Strain	Company	Features	Growth Requirements	Documentation
BL21(DE3)	Novagen	DE3 lysogen contains T7 polymerase upon IPTG induction. This strain is defficient of lon and omp-t proteases and is therefore suitable for expression of non-toxic genes.	There is no tight control over the expression, thus addition of 1% glucose to the growth medium should be considered. (Note: 1. This significantly attenuates growth rates. 2. Higher concentrations of IPTG should be used for induction.)
BL21(DE3)-pLysS	Novagen	DE3 lysogen expresses T7 polymerase upon IPTG induction. The pLysS plasmid produces T7 lysozyme to reduce basal level expression of the gene of interest. Thus it is suitable for expression of toxic genes. [pLysS contains the p15A origin. This origin allows pLysS to be compatible with plasmids containing the ColE1 or pMB1 origin (i.e. pUC- or pBR322- derived plasmids).]	Chloramphenicol 34ug/ml	Mechanism of inhibition of bacteriophage T7 RNA polymerase by T7 lysozyme.
BL21 Star-pLysS	Invitrogen	This strain is mutated in Rnase E, thus Rnase degradation is reduced, and protein expression may be increased. The pLysS presence allows tight control of expression. Use this strain for both soluble and insoluble protein production.	Chloramphenicol 34ug/ml	PDF
BL21-SI	Invitrogen	T7 polymerase in the DE3 is under control of the salt-inducible proU promoter. Induction of protein production at 0.1-0.5M of NaCl. Helps protein solubility.	LBON medium (LB w/o NaCl), 30^oc. Expression induction by NaCl, if controlled by a T7 promoter. Otherwise - IPTG.	Protocols (PDF)
BL21-AI	Invitrogen	BL21-AI was constructed by inserting a chromosomal copy of the T7 RNA polymerase gene under the tight control of the arabinose-inducible araBAD promoter.	Tetracyclin 12.5ug/ml Expression induction by arabinose. (If using pET vectors, IPTG is also required!) Glucose will repress this induction.	Detailed description & protocols (PDF)
Tuner	Novagen	Contains a mutation in the lac permease (lacZY) gene. This enables adjustable levels of protein expression throughout all cells in a culture. The lac permease (lacY) mutation allows uniform entry of IPTG into all cells in the population, which produces a concentration-dependent, homogeneous level of induction. By adjusting the concentration of IPTG, expression can be regulated from very low levels up to the robust, fully induced levels commonly associated with pET vectors. Lower level expression may enhance the solubility and activity of difficult target proteins.	None
Tuner pLysS	Novagen	Contains the pLysS plasmid (tighter control over expression) in addition to the lac permease mutation.	Chloramphenicol 34ug/ml
Origami	Novagen	Origami host strains are K-12 derivatives that have mutations in both the thioredoxin reductase (trxB) and glutathione reductase (gor) genes, which greatly enhances disulfide bond formation in the cytoplasm.	Kanamycin 15ug/ml Tetracyclin 12.5ug/ml	A short description (PDF)
Origami B	Novagen	Origami B host strains carry the same trxB/gor mutations as the original Origami strains, except that they are derived from a lacZY mutant of BL21. Thus the Origami B strains combine the desirable characteristics of BL21, Tuner™ and Origami hosts in one strain background.	Kanamycin 15ug/ml Tetracyclin 12.5ug/ml	The role of thioredoxin and glutharedoxin pathways in reducing protein di-sulfide bonds in E-coli cytoplasm
Origami B pLysS	Novagen		Kanamycin 15ug/ml Tetracyclin 12.5ug/ml Chloramphenicol 34ug/ml
Rosetta	Novagen	Rosetta host strains are BL21 lacZY (Tuner™) derivatives designed to enhance the expression of eukaryotic proteins that contain codons rarely used in E. coli. These strains supply tRNAs for the codons AUA, AGG, AGA, CUA, CCC, GGA on a compatible chloramphenicol resistant plasmid. The tRNA genes are driven by their native promoters.	Chloramphenicol 34ug/ml	A short description - PDF A short description (PDF)
Rosetta pLysS	Novagen	In Rosetta(DE3)pLysS the rare tRNA genes are present on the same plasmids that carry the T7 lysozyme.	Chloramphenicol 34ug/ml
Rosetta-gami-pLysS	Novagen	Rosetta-gami host strains are Origami derivatives that combine the enhanced disulfide bond formation resulting from trxB/gor mutations with enhanced expression of eukaryotic proteins that contain codons rarely used in E. coli. These strains supply tRNAs for AGG, AGA, AUA, CUA, CCC, GGA on a compatible chloramphenicolresistant plasmid. The tRNA genes are driven by their native promoters. In Rosettagami(DE3)pLysS the rare tRNA genes are present on the same plasmids that carry the T7 lysozyme.	Kanamycin 15ug/ml Tetracyclin 12.5ug/ml Chloramphenicol 34ug/ml
BL21 CodonPlus	Stratagene	BL21-CodonPlus-RIL chemically competent cells carry extra copies of the argU, ileY, and leuW tRNA genes. The tRNAs encoded by these genes recognize the AGA/AGG (arginine), AUA (isoleucine), and CUA (leucine) codons, respectively.	Tetracyclin 12.5ug/ml? Chloramphenicol 34ug/ml ?	A short description PDF (a detailed article)
AD494	Novagen	AD494 strains are thioredoxin reductase (trxB) mutants of the K12 strain that enable disulfide bond formation in the cytoplasm, providing the potential to produce properly folded active proteins.	Kanamycin 15ug/ml
BL21trxB	Novagen	BL21trxB strains possess the same thioredoxin reductase mutation (trxB) as the AD494 strains in the protease deficient BL21 background. The trxB mutation enables cytoplasmic disulfide bond formation.	Kanamycin 15ug/ml	The role of thioredoxin and glutharedoxin pathways in reducing protein di-sulfide bonds in E-coli cytoplasm
HMS174	Novagen	HMS174 strains provide the recA mutation in a K-12 background. Like BLR, these strains may stabilize certain target genes whose products may cause the loss of the DE3 prophage.	None
NovaBlue(DE3)	Novagen	NovaBlue(DE3) is a K-12 strain ideally suited as an initial cloning and expression host due to its high transformation efficiency and recA endA mutations, which result in high yields of excellent quality plasmid DNA. It olso contains DE3 for T7 polymerase expression. Ttight regulation of expression is conferred due to the presence of lacI^qrepressor encoded by the F episome.	Tetracyclin 12.5ug/ml
BLR	Novagen	BLR is a recA^- derivative of BL21 that improves plasmid monomer yields and may help stabilize target plasmids containing repetitive sequences or whose products may cause the loss of the DE3 prophage.	Tetracyclin 12.5ug/ml
C41(DE3)	Lucigen	Effective in expressing toxic and membrane proteins from all classes of organisms,including viruses,eubacteria,archaea,yeasts,plants,insects,and mammals. The strain C41(DE3)was derived from BL21(DE3) [E.coli F ompT hsdS B (r B -m B -) gal dcm (DE3)].This strain has at least one uncharacterized mutation that prevents cell death associated with expression of many toxic recombinant proteins.	None Protocols	A short description. A more detailed description. The toxicity of recombinant proteins in Escherichia coli: a comparison of overexpression in BL21(DE3), C41(DE3), and C43(DE3) (PDF)
C43(DE3)	Lucigen	Effective in expressing toxic and membrane proteins from all classes of organisms,including viruses,eubacteria,archaea,yeasts,plants,insects,and mammals.	None Protocols	A short description. A more detailed description. The toxicity of recombinant proteins in Escherichia coli: a comparison of overexpression in BL21(DE3), C41(DE3), and C43(DE3) (PDF)
Lemo21(DE3) (Site)	NEB	Lemo21(DE3) offers the host features of BL21(DE3) while also allowing for tunable expression of difficult clones. Tunable expression is achieved by varying the level of lysozyme (lysY), the natural inhibitor of T7 RNA polymerase. The level of lysozyme is modulated by adding L-rhamnose to the expression culture at levels from zero to 2000 µM. When Lemo21(DE3) is grown without rhamnose, the strain performs the same as a pLysS containing strain. However, optional addition of rhamnose tunes the expression of the protein of interest. For difficult soluble proteins, tuning the expression level may also result in more soluble, properly folded protein.	Chloramphenicol L-rhamnose (different concentratins), see protocol	Tuning E. Coli for membrane protein overexpression Optimizing Membrane Protein Overexpression in the Escherichia coli strain Lemo21(DE3)
SHuffle T7 (Site)	NEB	E. coli K12 cells engineered to form proteins containing disulfide bonds in the cytoplasm. Suitable for T7 promoter driven protein expression. Expresses constitutively a chromosomal copy of the disulfide bond isomerase DsbC. DsbC promotes the correction of mis-oxidized proteins into their correct form. The cytoplasmic DsbC is also a chaperone that can assist n the folding of proteins that do not require disulfide bonds.	Protocol
ArcticExpress and ArcticExpress (DE3) (Site)	Agilent Technologies	ArcticExpress Competent Cells are engineered to address the common bacterial gene expression hurdle of protein insolubility. These cells are derived from the high-performance Stratagene BL21-Gold competent cells, enabling efficient high-level expression of heterologous proteins in Escherichia coli.	For protein expression: Gentamycin 20ug/mL For transformation: no need for antibiotic other than the one of the transformed plasmid. For making compotent cells: Gentamycin 20ug/mL, Tetracycline 10ug/mL	Instruction manual

**Search for Additional bacterial strains**
Novagen	Selection Table of Novagen's Competent Cells Competent cells & Protocols (PDF) Competent Cells Overview
Invitrogen	Competent Cells, Table of competent cells
Stratagene	Competent Cells
Clontech	Electrocompetent & Chemically Competent E. coli and Yeast Cells
Takara	E. coli Competent Cells

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Entries since October 2007