Turnover of protein and nucleic acid in soluble and ribosome fractions of non-growing Escherichia coli

The stability of protein and of RNA has been examined in the ribosome and soluble fractions of non-growing E. coli. In both fractions there is balanced degradation and re-synthesis of protein at about 5% per h. The RNA of the ribosomes is also degraded at this rate but re-synthesized at only 1.5% per h. In the soluble fraction the rate of nucleic acid synthesis exceeds the rate of degradation, so that there appears to be net transfer of material from the ribosomes to the soluble fraction. Degradation of ribosomes supplies much of the free amino acids and almost all of the ribonucleotides passing through the free pool during starvation.