Are the Overnight Express Autoinduction Systems compatible with any expression host?
Because lactose is used for induction, expression hosts producing functional Lac permease (encoded by the lacY gene) and b-galactosidase (encoded by the lacZ gene) are required. Strains with nonfunctional Lac permease will not efficiently transport lactose for induction, and strains with nonfunctional b-galactosidase will not convert a portion of the transported lactose to the necessary allolactose inducer. The system is compatible with host strains such as BL21, Rosetta™, Rosetta 2, and their DE3 lysogen derivatives. If the expression vector uses a T7lac promoter, as many of the pET vectors do, a host strain without a pLysS plasmid is recommended. The combination of the T7 lysozyme (expressed by the pLysS plasmid) and the lac repressor (encoded by vectors carrying the T7lac promoter) causes significantly reduced protein expression in the Overnight Express Autoinduction Systems. When the “plain” T7 promoter is used, the low level of lysozyme produced by pLysS has little effect on expre
