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 beta-galactosidase was studied in several strains of Escherichia 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 greater than acetate greater than glycerol greater than glucose, and that of beta-galactosidase was found in the order: glycerol greater than acetate greater than succinate greater than glucose. Rate of accumulation of cyclic AMP in the culture filtrate was in the order: succinate greater than acetate greater than glycerol greater than 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 beta-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.

Cyclic nucleotides in procaryotes.

“…A comparison of the effect of cAMP on induction of tryptophanase and fi-galactosidase in E. coli showed that some combinations of carbon sources inhibited induction of tryptophanase while stimulating induction of ,B-galactosidase. It was proposed that control elements other than the CRP-cAMP complex respond to the catabolic situation in the cell and that these hypothetical control elements could control some but not all catabolic operons (24). It should be pointed out that catabolite repression occurs in some microorganisms, such as Bacillus megaterium, that contain no cAMP (255).…”

Growth rate regulation of lac operon expression in Escherichia coli is cyclic AMP dependent

“…The regulatory protein, cAMP receptor protein (CRP), binds cAMP and causes the transcriptional activation or repression of many promoters [10]. The intracellular cAMP concentrations or the ability of the cell to accumulate cAMP are different in different nutrient compositions [11]. Early studies showed that changes in the dilution rate do not vary the cAMP level in E. coli , but this may be due to the technical difficulties of measuring low levels of cellular cAMP [12,13].…”

Evidence for transcription antitermination control of tryptophanase operon expression in Escherichia coli K-12

“…The cAMP-CRP complex makes up a positive-acting element required for efficient transcription initiation at catabolite-sensitive promoters; mutants deficient in CRP or adenylate cyclase are incapable of inducing the tna operon (reviewed in reference 16). However, other factors, independent of cAMP, probably also play significant roles in the catabolite repression of tna operon expression (10,11).…”