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Extended Data Fig. 5 | Absolute and relative concentrations of key
metabolites in the shift from glucose to acetate. a, Intracellular
concentrations of F6P in the three biological repeats (circles, squares and
triangles) of the shift from glucose to acetate presented in Fig. 2. The dashed
line represents the steady-state level of F6P for growth on acetate. The F6P
concentration is low compared with the Michaelis constants of key enzymes
Pgi and TktA, which catalyse the first reactions from F6P in the synthesis of E4P
and R5P, essential precursors for biomass production. b, Intracellular
concentrations of PEP during the lag phase that follows a shift from glucose to
acetate and from mannose to acetate. Steady-state (s.s.) concentrations are
also shown. PEP acts as a key repressor of glycolytic f lux by inhibiting Pf k^51. The
PEP concentration remained low throughout lag phase, even by comparison
with the steady-state concentration on glucose, when Pf k is very active. c, Time
courses of FBP and PEP concentrations throughout lag phase during a shift
from glucose to acetate. We normalized the concentrations by their
steady-state concentration (dashed line) during exponential growth on
acetate. During the lag phase, FBP drops from its steady-state level for growth
on glucose, which is more than 100-fold higher than its steady-state level on
acetate (normalized to 1). PEP remains at very low concentrations and slowly
builds up, together with FBP, 1.5 h after the shift. In our model, we attribute this
slow build-up to the need for protein synthesis to increase levels of
gluconeogenic enzymes.