The synthesis of messenger RNA without protein synthesis: I. Studies with thymineless strains of Escherichia coli

Abstract

Escherichia coli , deficient in the ability to synthesize thymine, uracil and an amino acid, synthesize a small fraction of their normal RNA from uracil in the absence of thymine and the amino acid. The synthesis of even this fraction of RNA is inhibited by concomitant DNA synthesis. Most (75%) of the RNA made appears on the ribosomes and can be degraded on these structures in the presence of inorganic phosphate. When synthesized in the presence of an inducer of β -galactosidase, the RNA appears to permit the rapid synthesis of a small amount of this enzyme in the apparent absence of the inducer. These observations are consistent with the hypothesis that the RNA made in the absence of an essential amino acid and of protein synthesis is largely messenger RNA.