Regulation of Lac Messenger Ribonucleic Acid Synthesis by Cyclic Adenosine 3',5'-Monophosphate and Glucose

Cyclic adenosine 3',5'-monophosphate reverses the glucose repression of β-galactosidase synthesis in Escherichia coli induced for enzyme synthesis. In this report, we describe hybridization assays for the measurement of synthesis rates of lac messenger RNA and demonstrate that cyclic adenosine 3',5'-monophosphate and glucose alter rates of mRNA production in proportion to their effects on β-galactosidase synthesis. Thus we confirm earlier indirect measurements which indicate that control of β-galactosidase synthesis by cyclic adenosine 3',5'-monophosphate and glucose occurs at the level of transcription. In addition, we show that these effects on lac mRNA synthesis are observed in cultures incapable of enzyme synthesis and that glucose does not affect the rate of degradation of lac mRNA.