TRANSLATIONAL REGULATION IS RESPONSIBLE FOR GROWTH-RATE-DEPENDENT AND STRINGENT CONTROL OF THE SYNTHESIS OF RIBOSOMAL-PROTEINS L11 AND L1 IN ESCHERICHIA-COLI

The physiological importance of translational regulation in controlling the synthesis of ribosomal proteins from the L11 ribosomal protein operon was determined for the classical regulatory phenomena of growth rate dependence and stringent control. Translational regulation of the L11 operon by ribosomal protein L1, the L11 operon-specific translational repressor protein, was abolished by introducing a chromosomal mutation that causes an alteration of the site where L1 interacts with L11 operon mRNA. It was found that abolishing translational regulation of the L11 operon also abolished growth-rate-dependent regulation and stringent control of the L11 operon ribosomal proteins without affecting the normal regulation of ribosomal proteins from other operons that are not regulated by L1. These results show that both growth-rate-dependent control and stringent control of ribosomal protein synthesis in the L11 operon are a direct result of translational regulation.