Glucose and the Metabolism of Adenosine 3′:5′-Cyclic Monophosphate in Escherichia coli

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Abstract
Measurements of adenosine 3':5'-cyclic monophosphate (cAMP) concentrations have been made in Escherichia coli under various conditions. Different strains of E. coli accumulate different extracellular concentrations of cAMP (0.2-4 mum) at stationary phase. Mutation at the RNA control locus does not affect the accumulation pattern. Growth of the bacteria in minimalsalts medium leads to a greater accumulation of cAMP than growth in nutrient broth. Partition studies show that essentially all of the cAMP that is accumulated is found in the medium rather than in the cells. Kinetic studies show that most of the cAMP is formed coincidentally with exhaustion of glucose from the medium. Growth on high concentrations of glucose leads to inhibition of cAMP formation. Other carbon sources cannot substitute for glucose in this inhibitory effect. Measurements of enzyme activities indicate that glucose suppression of cAMP formation cannot be accounted for by a decreased activity of adenylate cyclase or an increased activity of cAMP phosphodiesterase (EC 3.1.3.7).