Ribosome maturation of Escherichia coli growing at different growth rates.

The data reported here are consistent with the hypothesis that the rate of ribosome assembly in vivo approximates a constant fraction of the generation time for the four rates studied. This conclusion is indicated by the following. (i) There is an increased lag period before radioisotopically labeled uracil appears in 23 and 16S ribosomal ribonucleic acid of 70S ribosomes as a function of growth rate. (ii) The time necessary for (3)H-uracil in the 43S ribonucleoprotein precursor to the 50S subunit to assume a position at 50S in sucrose gradients is greatly increased inversely to the growth rate.