MilliporeSigma™ Novagen™ Tuner™ (DE3) pLacI Competent Cells

Description

• Expression host strains for pETBlue™ and pTriEx™ vectors are lDE3 lysogens that also carry the compatible pLacI plasmid, encoding the lac repressor
• The pLacI plasmid confers chloramphenicol resistance and provides enough lac repressor to inhibit transcription from the T7lac promoter in the absence of inducer
• The NovaBlue host strain is recommended for initial cloning with pETBlue and pTriEx vectors due to its superior transformation efficiency and high yields of high-quality plasmid DNA
• Note that these strains are not recommended for use with pET, pACYCDuet™, pCDF, pRSF, pCOLADuet™ or pETcoco™ vectors
• Tuner™ strains are lacZY deletion mutants of BL21 and enable 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
• In Tuner(DE3)pLacI, the rare tRNA genes are present on the same plasmid that carries the lac repressor gene
• DE3 indicates that the host is a lysogen of λDE3, and therefore carries a chromosomal copy of the T7 RNA polymerase gene under control of the lacUV5 promoter
• Such strains are suitable for production of protein from target genes cloned in pET vectors by induction with IPTG.