Catabolite repression in Escherichia coli mutants lacking cyclic AMP receptor protein.

Abstract
Pleiotropic carbohydrate-positive pseudorevertants were isolated from a specific class of rho-crp double mutants of E. coli carrying both defective transcription termination protein, rho and cAMP receptor protein. The modulation of catabolite repression of .beta.-galactosidase, amylomaltase and tryptophanase was studied in the pseudorevertants. These mutants exhibit catabolite repression. Because catabolite-sensitive operons can be expressed in the absence of functional cAMP receptor protein, this would suggest that the cAMP-receptor protein complex is not the exclusive mediator of catabolite repression and that rho might be involved in the regulation of catabolite-sensitive operons.