화학공학소재연구정보센터
Biotechnology Progress, Vol.18, No.3, 672-674, 2002
Effect of lacY expression on homogeneity of induction from the P-tac and P-trc promoters by natural and synthetic inducers
The role of the Escherichia colt lactose permease (LacY) in the homogeneous induction of the lactose-inducible promoters P-tac, and P-trc, by the natural inducer lactose and the synthetic inducer isopropyl-beta-D-thiogalactopyranoside (IPTG) was investigated. Lactose requires active transport by LacY, whereas IPTG can freely penetrate the cell wall. In E. coli strains lacking a functional LacY, IPTG is required for induction of P-tac and P-trc. In E. coli strains carrying a functional LacY, induction of P-trc and P-tac with intermediate concentrations of lactose gave rise to two subpopulations, one fully induced and one uninduced, whereas a single, fully induced population resulted when high inducer concentrations were used. In contrast, induction with IPTG gave rise to a single population of cells at all inducer concentrations in both lacY and lacY(+) strains.