Synthesis and breakdown of messenger RNA without protein synthesis

The synthesis and breakdown of alkaline phosphatase messenger RNA was examined in vivo using a strain of Escherichia coli which produces a defective messenger RNA that can be translated correctly after incorporation of 5-fluorouracil. Amino acid auxotrophs of this strain possessing either the stringent or relaxed allele governing RNA synthesis were tested for production of alkaline phosphatase messenger RNA. It was found that 5-fluorouracil is not incorporated into amino acid-starved stringent cells, but that addition of chloramphenicol permits incorporation. The rates of synthesis and breakdown of this message in the relaxed strain are almost the same with or without protein synthesis, suggesting that transcription and translation are not necessarily coupled.