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 coli 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.
Khlebnikov
Artem
A
Department of Chemical Engineering, University of California, Berkeley, California 94720-1462, USA.
Keasling
Jay D
JD
D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D007544:Isopropyl Thiogalactoside; D026901:Membrane Transport Proteins / Q000235:genetics*; D009004:Monosaccharide Transport Proteins; D011401:Promoter Regions, Genetic; D027981:Symporters
D029968:Escherichia coli Proteins; C050221:LacY protein, E coli; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D027981:Symporters; D007544:Isopropyl Thiogalactoside; C021499:lactose permease