Biosynthesis of 50S Ribosomal Proteins During the Outgrowth of Bacillus Subtilis Spores

The biosynthesis of 14 protein bands from 50S ribosomes was studied during the outgrowth of Bacillus subtilis W23 spores. The time at which the synthesis of each protein band begins and the patterns of synthesis that each displays were determined by comparing the incorporation of (3)H-phenylalanine during five intervals throughout the first hour of outgrowth with the incorporation of (14)C-phenylalanine between 145 and 150 min. The majority of the proteins in the 14 bands analyzed were synthesized as early as 5 to 10 min. The bands could be grouped on the basis of their labeling patterns as well as the time required for them to achieve a high rate of synthesis. Three bands did not achieve a high rate of synthesis until after 30 min of outgrowth, and at least one of the proteins from these bands appeared to be located on the exterior of the 50S subunit. The significance of the proteins from these three bands is discussed in terms of the late formation of new, mature 50S subunits during outgrowth.