Abstract
The effect of different cellular free-energy states on the uptake
of methyl alfa-D-glucopyranoside, an analoque of glucose, by
Escherichia coli phosphoenolpyruvate:carbohydrate
phosphotransferase system was investigated. The intracellular
ATP/ADP ratio was varied by changing the expression of the atp
operon, which codes for the H+-ATPase, or by adding an uncoupler
of oxidative phosphorylation or an inhibitor of respiration.
Corresponding initial phosphotransferase uptake rates were
determined using an improved uptake assay that works with growing
cells in steady state. The results show that the initial uptake
rate was decreased under conditions of lowered intracellular
ATP/ADP ratios, irrespective of which method was used to change
the cellular energy state.. When either the expression of the atp
operon was changed or 2,4-dinitrophenol was added to wild-type
cells, the relationship between initial phosphotransferase uptake
rate and the logaritm of the ATP/ADP ratio was approxomately
linear. These results suggest that the cellular free-energy state,
as reflected in the intracellular ATP/ADP ratio, plays an
important role in regulating the activity of the
phosphotransferase ssystem.
Original language | English |
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Journal | European Journal of Biochemistry |
Volume | 235 |
Pages (from-to) | 225-230 |
ISSN | 0014-2956 |
Publication status | Published - 1996 |