CYCLIC ADENOSINE-3',5'-MONOPHOSPHATE LEVELS IN PSEUDOMONAS-PUTIDA AND PSEUDOMONAS-AERUGINOSA DURING INDUCTION AND CARBON CATABOLITE REPRESSION OF HISTIDASE SYNTHESIS

Inducibility of histidase (histidine ammonia-lyase, EC 4.3.1.3) in P. putida and P. aeruginosa was strongly affected by succinate-provoked catabolite repression but this did not occur as a consequence of reduced intracellular cAMP levels, and repression could not be alleviated by exogenously added cAMP. Milder repression of histidase by lactate was also not reversed by the addition of cAMP. These results, along with data showing intracellular cAMP levels remained essentially constant during growth on such diverse carbon sources as histidine, acetamide, glucose and succinate, indicated that catabolite repression of histidase synthesis by efficient carbon sources was not mediated through variations in internal cAMP.