Metabolism of cyclic adenosine 3',5' monophosphate and induction of tryptophanase in Escherichia coli

Abstract

The relationship between cyclic adenosine 3',5' monophosphate (cyclic AMP) metabolism and the induction of tryptophanase and β galactosidase was studied in several strains of E. coli grown with succinate, acetate, glycerol, or glucose as the carbon source. No consistent relationship between the intracellular concentration of cyclic AMP in the several strains cultured and the various carbon sources was discerned. In E. coli K-12-1 the induction of tryptophanase was found to vary in the order: succinate > acetate >> glycerol >>> glucose, and that of β galactosidase was found in the order: glycerol > acetate > succinate > glucose. Rate of accumulation of cyclic AMP in the culture filtrate was in the order: succinate > acetate > glycerol > glucose. The addition of glycerol to E. coli K-12-1 grown in acetate caused inhibition of tryptophanase and slight inhibition of accumulation of extracellular cyclic AMP. These same conditions caused β galactosidase induction to be stimulated. The addition of exogenous cyclic AMP to cultures grown with four different carbon sources had an effect characteristic for each of the two enzymes studied as well as each individual carbon source. The results suggest that there are control elements distinct from cyclic AMP and its receptor protein which respond to the catabolic situation of the cell.