The participation of ribonuclease in the degradation of Escherichia coli ribosomal ribonucleic acid as revealed by oligonucleotides accumulation in the phosphorus-deficient stage

Abstract

1. 1. Escherichia coli ribosomal RNA degradation during the phosphorus-deficient stage 1,2 was investigated by analysis of its degradation products. 2. 2. After exhaustion of the phosphorus in the medium, 32P in the 50 % ethanolsoluble fraction of the bacterial cell increased greatly in parallel with the degradation of ribosomal RNA, while trichloroacetic acid-soluble 32P did not. 3. 3. Soon after phosphorus exhaustion, most of the ethanol-soluble 32P consisted of characteristic oligonucleotides. Later, inorganic phosphate increased gradually parallel with a decrease in oligonucleotides in ethanol extracts. 4. 4. The differences in the base ratios, the terminal structures and other properties of these oligonucleotides suggest that the breakdown of ribosomal RNA was caused mainly by ribosomal latent ribonuclease (EC 2.7.7.17) 3. These oligonucleotides, in their turn, were found to be finally converted to inorganic phosphate and nucleosides by the cooperation of alkaline phosphomonoesterase (EC 3.1.3.1) 2,4 and cyclic phosphodiesterase 5,6.