Isolation and characterization of an Escherichia coli mutant affected in the regulation of adenylate cyclase

Abstract

An E. coli mutant, cyaR1, affecting regulation of adenylate cyclase expression or activity is described. It was obtained as a thermoresistant revertant of a strain harboring a thermosensitive transcription termination factor, rho (rho-15). This mutant failed to synthesize cAMP and exhibited a carbohydrate-negative phenotype. A secondary mutation at the crp locus (crpC) restored the ability of the mutant to synthesize cAMP, enabled the expression of catabolite-sensitive operons, and conferred on the strain an extreme sensitivity to catabolite repression. The crpC mutation restored the pleiotropic carbohydrate-positive phenotype even in a .DELTA.cya background. This suggests that the cAMP receptor protein regulates negatively either the activity or synthesis of adenylate cyclase. The cyaR1 mutation is probably either in a regulatory protein or a regulatory site of adenylate cyclase.