FIG. 5.

Effect of glpFKX on E. coli CAG2242 cell viability. Viable cells were counted at the designated times as described in Materials and Methods. Cells transformed with the indicated plasmids were cultured in the absence and presence of 4 mM spermidine. Symbols: ○, pUC119 and no spermidine; ▵, pUCglpFK and no spermidine; ●, pUC119 and 4 mM spermidine; ♦, pUCglpF and 4 mM spermidine; ▪, pUCglpK and 4 mM spermidine; ▾, pUCglpX and 4 mM spermidine; ▴, pUCglpFK and 4 mM spermidine; ×, pUCglpFKX and 4 mM spermidine. When the gene was oriented under the control of the lac promoter, 1 mM IPTG was added at 6 h after the onset of cell culture. In the case of glpF, essentially the same results were obtained with the plasmids with either the glpFK promoter (pUCglpF-1) or the lac promoter (pUCglpF-2). Each point is the average of duplicate determinations.