Changes in the intracellular concentration of acetyl-CoA and malonyl-CoA in relation to the carbon and energy metabolism of Escherichia coli K12.
Intracellular concentrations of acetyl-CoA and malonyl-CoA in Escherichia coli K12 were determined by a malonyl-CoA: acetyl-CoA cycling technique. Under aerobic growth conditions with glucose the acetyl-CoA and malonyl-CoA concentrations varied over a range of 0.05-1.5 nmol (mg dry wt)-1 (20-600 microM) and 0.01-0.23 nmol (mg dry wt)-1 (4-90 microM), respectively. The intracellular concentration of acetyl-CoA was highest in exponentially growing cells and it fell rapidly to less than 5% of the maximum level when the organism entered stationary phase after exhaustion of glucose. A linear relationship was observed between the intracellular concentration of total acyl-CoA and the logarithm of the concentration of glucose in the medium. Consequently, the acetyl-CoA/malonyl-CoA ratios also varied drastically, in a range of 0.6-41.7, under different conditions. Of several carbon sources tested, glucose was the most effective for promoting the synthesis of cellular acetyl-CoA. For cells grown on glycerol or acetate the maximum concentrations of total acyl-CoA were significantly lower. In cells incubated with citrate (not used as a carbon source by E. coli), the level was consistent with that in cells starved for exogenous carbon sources.
Takamura
Y
Y
Department of Agricultural Chemistry, Faculty of Agriculture, Ibaraki University, Japan.
Nomura
G
G
D000105:Acetyl Coenzyme A / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism*; D003470:Culture Media; D004734:Energy Metabolism; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology; D008316:Malonyl Coenzyme A / Q000378:metabolism
D003470:Culture Media; D008316:Malonyl Coenzyme A; D000105:Acetyl Coenzyme A; D002244:Carbon; D005947:Glucose