• Induce high level protein expression from lac based promoters (T7, T5-lac, tac, trc, lac)
• Tightly regulate expression from T7 promoters with HI-Control BL21(DE3) Chemically Competent Cells
• Clone targets and reduce background protein expression with HI-Control 10G Chemically Competent Cells

The HI-Control™ strains are based on E. cloni 10G ( DH10B) and BL21(DE3) strains. These strains harbor a plasmid bearing a constitutive lacI repressor gene, which provides tight control over promoters containing the lacO operator.

Reduce leaky expression: The LacI repressor protein binds to the lacO operator, blocking transcription of downstream genes. In the absence of an induction agent such as lactose sugar or IPTG, target protein expression from the adjacent promoter is greatly reduced.

Obtain high protein yields: Both 10G and BL21(DE3)-based strains express high levels of protein. For expression from a T7 promoter, select the HI-Control BL21(DE3) strain. Other lac-based promoters like T5-lac, tac, trc, and lac, can be used in either HI-Control strain.

Achieve high efficiency transformations:  Highly efficient competent cells give excellent results from small amounts of plasmid DNA. 

Genotypes:

HI-Control™ BL21 (DE3): F- ompT hsdSB (rB- mB-) gal dcm (DE3) Mini-F lacIq1(GentR)

HI-Control™ 10G: mcrA Δ(mrr-hsdRMS-mcrBC) endA1 recA1 ɸ80dlacZΔM15 ΔlacX74 araD139 Δ (ara,leu)7697 galU galK rpsL (StrR) nupG λ− tonA Mini-F lacIq1 (GentR)