Short Papers Site of Action of 3',5'-cyclic Adenosine Monophosphate in Production of Tryptophanase in Escherichia Colz

3',5' cydic-AMP (CAMP) will stimulate the rate of tryptophanase synthesis in Esckrichia coli cultures induced with tryptophan. Adding CAMP after the initiation of messenger RNA synthesis was blocked by rifampicin, did not stimulate tryptophanase synthesis. This indicates that cAMP acts at initiation of either transcription or translation and not at the level of chain elongation of either the messenger or the polypeptide chain. XPERIMENTS using actinomycin D to block RNA synthesis suggested that E cAMP affects the translation of the tryptophanase messenger (PASTAN and PERLMAN 1969). On the other hand, when RNA synthesis was blocked by rifampicin, it was suggested that cAMP affects transcription of the tryptophanase messenger (DEL CAMPO, RAMIREZ and CANOVAS 1970). Since experiments with a temperature-sensitive mutant of Escherichia coli that fails to synthesize functional (Y and p-galactosidase or tryptophanase in the absence of cAMP at 43", pointed out the possibility that the synthesis of these three enzymes is affected similarly by cAMP (SIMON and APIRION, manuscript in preparation), we decided to further investigate the site of action oi cAMP in stimulation of tryptophanase synthesis.