One Shot® BL21 Star™ (DE3) E. coli are chemically competent cells designed for applications that require high-level expression of non-toxic recombinant proteins from low copy number, T7 promoter-based expression systems (e.g., Champion™ pET vectors). One Shot® BL21 Star™ (DE3) Chemically Competent cells are controlled for a transformation efficiency of 1 x 108 cfu/ µg plasmid DNA.
• A genotype that promotes high mRNA stability and protein yield
• Ideal for use with low copy number, T7 promoter-based plasmids
• The single tube, single use format allows all transformation steps to take place in the same tube, thereby helping to save time and prevent contamination

Enhanced Expression of Non-Toxic Recombinant Proteins
One Shot® BL21 Star™ (DE3) cells contain the DE3 lysogen that carries the gene for T7 RNA polymerase under control of the lacUV5 promotor, and IPTG is required to induce expression. This strain also offers enhanced mRNA stability due to a mutation in the RNaseE gene (rne131), which reduces levels of endogenous RNases and mRNA degradation, thereby increasing the stability of mRNA transcripts and increasing protein yield. Protein expression is further enhanced by the absence of the lon and outer membrane (OmpT) proteases, which reduces degradation of heterologous proteins.

Note: The BL21 Star™ strains have higher basal expression of heterologous genes than BL21 strains, due to the increased stability of mRNA. Therefore, these strains may not be useful for expression of toxic genes.

Genotype:
F-ompT hsdSB (rB-, mB-) galdcmrne131 (DE3)

Find the Strain and Format That You Need
We also offer many other different strains and formats of chemically competent cells and electrocompetent cells to help meet your specific transformation needs. For expression of toxic proteins, choose BL21-AI™ One Shot® Chemically Competent E. coli.

For Research Use Only. Not intended for animal or human diagnostic or therapeutic use.