Abstract
Gronlund, Audrey F. (University of British Columbia, Vancouver, B.C., Canada), and J. J. R. Campbell. Enzymatic degradation of ribosomes during endogenous respiration of Pseudomonas aeruginosa. J. Bacteriol. 90:1-7. 1965.-From sedimentation analyses it was found that the ribosomal content of Pseudomonas aeruginosa decreased during endogenous respiration. A greater degree of degradation of 50S than 30S ribosomes occurred during the 3-hr starvation period. The enzyme responsible for the initiation of ribosome degradation and present in the ribosome fraction was identified as polynucleotide phosphorylase. The enzyme was inactive in intact 70S ribosomes, but was active in low magnesium ion concentrations which allowed the 70S ribosome to dissociate. Polynucleotide phosphorylase was not solubilized after dissociation of the 70S particle, but remained firmly attached to the 50S and 30S ribosomes, the ribonucleic acid of which served as substrate.