E.coli BL21-Gold(DE3)大腸桿菌表達宿主菌及感受態細胞

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BL21-Gold-derived expressionstrains are ideal for performing protein expression studies that utilize the T7RNA polymerase promoter to direct high-level expression. Derived from Escherichiacoli B, these expression strains naturally lack the Lon protease, which candegrade recombinant proteins. In addition, these strains are engineered to bedeficient for a second protease, the OmpT protein. These BL21-Gold-derivedexpression strains incorporate major improvements over the original BL21strain. The BL21-Gold strains feature the Hte phenotype present in the highestefficiency Agilent competent cell strain, XL10-Gold.4 The presence of the Htephenotype increases the transformation efficiency of the BL21-Gold cells to>1 × 108 cfu/μg of pUC18 DNA. In addition, the gene that encodesendonuclease I (endA), which rapidly degrades plasmid DNA isolated by mostminiprep procedures, is inactivated. These two improvements allow directcloning of many protein expression constructs. All three of theBL21-Gold-derived expression strains are resistant to tetracycline. Inaddition, the BL21-Gold(DE3)pLysS strain is resistant to chloramphenicol.

BL21-Gold(DE3) is anall-purpose strain for high-level protein expression and easy induction. TheBL21- Gold(DE3)pLysS strain provides tighter control of protein expression forexpression of toxic proteins. When used with the CE6 bacteriophage, theBL21-Gold cells provide the tightest control of protein expression. Table Iillustrates the features of the BL21-Gold expression strains for proteinexpression.

Genotype E. coli BF- dcm+ Hte ompT hsdS(r_B- m_B-) gal λ(DE3) endA Tet^r