Extended Data Fig. 8 | Preshift overexpression of glycolytic enzymes. a–d,
Lag times following shifts from glucose to: a, acetate; b, pyruvate; c, malate; d,
succinate. The graphs compare the effects of preshift overexpression of the
glycolytic enzymes PykF (strain NQ1543) and Pf k (strain NQ1544) with a control
enzyme, ArgA (strain NQ1545). Each protein was overexpressed from the same
plasmid (pNT3) using the tac promoter. Horizontal lines and error bars indicate
means and standard deviation (n = 4). Lag times more than doubled as a result
of preshift overexpression of Pf k or PykF. Thus, the residual activity of
glycolytic enzymes is important in lag phase, despite the allosteric regulation
of these glycolytic enzymes. Consistent with this picture, the concentration of
PEP—a key regulatory metabolite and repressor of glycolytic f lux—remained
low throughout lag phase, even compared with steady-state levels on glycolytic
carbons (Extended Data Fig. 5).