The control of ribonucleic acid synthesis in Escherichia coli. IV. Relevance of unusual phosphorylated compounds from amino acid-starved stringent strains.

Stringent strains of Escherichia coli are shown to produce one, and usually two, 82P-labeled compounds specifically in response to amino acid starvation. This pattern of labeling is not observed in three derived relaxed strains. Comparison of properties of the system regulating the synthesis of these compounds with those of the amino acid control of RNA biosynthesis suggests that the unusual compounds participate in an early step in the mechanism which leads to the slowing of RNA biosynthesis during amino acid starvation of stringent strains.