Data from: Homeostasis of metabolites in Escherichia coli on transition from anaerobic to aerobic conditions and the transient secretion of pyruvate

We have developed a method for rapid quenching of samples taken from
chemostat cultures of Escherichia coli that gives reproducible and
reliable measurements of extracellular and intracellular metabolites by 1H
NMR and have applied it to study the major central metabolites during the
transition from anaerobic to aerobic growth. Almost all metabolites showed
a gradual change after perturbation with air, consistent with immediate
inhibition of pyruvate formate-lyase, dilution of overflow metabolites and
induction of aerobic enzymes. Surprisingly, although pyruvate showed
almost no change in intracellular concentration, the extracellular
concentration transiently increased. The absence of intracellular
accumulation of pyruvate suggested that one or more glycolytic enzymes
might relocate to the cell membrane. To test this hypothesis, chromosomal
pyruvate kinase (pykF) was modified to express either PykF-green
fluorescent protein or PykF-FLAG fusion proteins. Measurements showed that
PykF-FLAG relocates to the cell membrane within 5 min of aeration and then
slowly returns to the cytoplasm, suggesting that on aeration, PykF
associates with the membrane to facilitate secretion of pyruvate to
maintain constant intracellular levels.