On the control of ribosomal protein biosynthesis in Escherichia coli. II. Studies during recovery from amino acid starvation.

The rate of synthesis of ribosomal proteins relative to that of total protein was measured at various times during recovery from arginine starvation in isogenic re+ and rel- strains of Escherichia coli K 12. Total ribosomal proteins are preferentially synthesized early during recovery. Higher rates of synthesis are obtained in the rel+ strain than in the rel- strain. Differential rates of synthesis of individual ribosomal proteins are observed at the various times studied. The rate of synthesis of individual proteins increases with time up to maximum values then the rates come down to values similar to those found in exponentially growing cells. The time of restart of synthesis of each protein has been estimated (1) by the time at which the maximum value is reached, and (2) by measuring the rate of synthesis at early time (3 min). Most ribosomal proteins behave similarlly in rel- and rel+ strains. Proteins have been listed from highly labelled (early proteins) to poorly labelled (late proteins). The significance of the order of restart is considered.